Ad-Libitum Paleo Diet W/ a Handful of Simple Rules Cuts 5-7 kg of Body Fat in 12 Weeks - Plus: Paleo Research Overview

Ad-Libitum Paleo Diet W/ a Handful of Simple Rules Cuts 5-7 kg of Body Fat in 12 Weeks - Plus: Paleo Research Overview

dieting health insulin resistance lean mass lose fat lose weight muscle loss paleo paleolithic eating whole foods

Yes, these foods were "allowed" - Even nuts, albeit in limited amounts.

Ok, I have to admit that I have repeatedly made fun of "paleo" in the past. Its "cultish", sometimes even "sectarian" appeal is and will remain as hilarious in my eyes as the (for some people life-or-death-)question whether certain foods "are paleo" or not (who cares, as long as they are healthy?). If you happen to have seen my presentation at the Paleo Convention in Berlin, last year, you will know that, despite my apathy against the quasi-religious sides of "paleo", I do appreciate a certain set of "rules" or "principles" (or whatever you may call them) all iterations of "paleo" have in common.

These principles work! And they have just been shown to help middle-aged type II diabetics (age 59±8 years) shed a quite impressive 6.7 kg of body fat (w/out exercise "only 5.7kg) in 12 weeks - without dieting as in not eating, although you're hungry (Otten. 2016).

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As the headline already tells you, the subjects, individuals diagnosed with type 2 diabetes within the past 10 years, who had a BMI of 25–40 kg/m2 and were weight stable (i.e. <5% weight loss) for 6 months (that's important, because otherwise the data on the energy deficit in Figure 1, which was calculated as baseline vs. study intake would be inaccurate) were allowed to eat "as-libitum", which practically means "as much as they wanted", as long, as they adhered to (a) "paleo foods", i.e. lean meat, fish, seafood, eggs, vegetables, fruits, berries, and nuts, but no cereals, dairy products, legumes, refined fats, refined sugars, and (extra) salt (canned fish and cold cuts like ham were allowed) and (b) followed the following simple food-specific rules:

• 

  Paleo Goes "Real Science" - First Meta-Analysis of Available RCTs Shows Improvements in Health + Body Composition | learn more

  eggs - maximally 1–2/day, and no more than 5/week,
• potatoes - only 1 medium sized potato per day
• dried fruit - 130 g/day, not more,
• nuts - 60 g/day, so no snacking on almonds 24/7
• rapeseed or olive oil - maximum 15 g/day
• honey and vinegar - only small amounts as flavoring in cooking
• coffee & tea - max 300 ml/day (each, I assume)
• red wine - only one glass per week

Since the participants were also instructed to drink mainly still water, you will probably not be surprised that all subjects, irrespective of whether they had been randomly assigned to the no exercise or exercise group ended up in a significant energy deficit - in spite of being allowed to eat "ad-libitum" (see Figure 1 for the most relevant information about their diet(s)).

Figure 1: Energy and macronutrient intake; differences, rel. + abs. above bars (Otten. 2016).

It is also not surprising that the extra-exercise (1h of exercise, 3x per week | details see blue box below) that was done on top of the (at least) 30 min of moderate intensity exercise like brisk walking all patients had been prescribed as part of their regular T2DM treatment, almost doubled the energy deficit of the subjects in the paleo + exercise, i.e. the PD-EX group (remember: the subjects were allowed to eat more, as long as they stuck to the previously presented rules - since the intake of foods like steak or chicken breast was not limited, they would have been able - within certain limits - to significantly increase their energy intake and still did not fully compensate the energy expended during the workouts; this should remind you of previous articles of mine outlining that "exercise does not just make you hungry" | learn more)

What about compli-ance? Both groups increased their relative intake of protein and their intake of monounsatu-rated and polyunsatu-rated fatty acids. Both groups lowered their intake of carbohydrates and saturated fatty acids. The reduction of sodium intake was only significant in the PD-EX group. Nine of the 14 participants in the PD-EX group completed the 36 exercise sessions according to the study protocol. The remaining five participants completed between 27 and 35 workouts during the study period. The participants in the PD-EX group increased the cumulative weight load (weight × repetitions × sets) with the leg press during one exercise session from 1350 kg (900−1800) to 3000 kg (2700−4000) after 12 weeks.

What did the 1h workouts look like? The PD-EX group underwent a program comprising a combination of aerobic exercise and resistance training in 1-h sessions three times weekly at the Sports Medicine unit at Umeå University. The exercise sessions were performed on weekdays, with at least 1 day of rest between sessions. They were supervised by experienced personal trainers with bachelor’s degrees in Sports Medicine.

All exercise sessions started with aerobic exercise. The first session of each week consisted of low-intensity aerobic training at 70% of the maximum heart rate on a crosstrainer (Monark Prime, XT 50, Vansbro, Sweden). The second session of the week consisted of ten high-intensity sprint intervals at 100% of the maximal workload on a cycle-ergometer (Monark, Ergomedic 839E, Vansbro, Sweden), with low-intensity cycling between the sprints. The third session of each week comprised six moderate-intensity 5-min intervals between 45 and 60% of maximal workload on a cycle-ergometer. The duration/workload of the intervals increased every other week. When necessary, the intensity of the aerobic exercise sessions was adjusted in accordance with the participant’s performance.

After the aerobic exercise, the sessions progressed to resistance training with both upper and lower body exercises, including leg presses, seated leg extensions, leg curls, hip raises, flat and incline bench presses, seated rows, dumbbell rows, lat pull-downs, shoulder raises, back extensions, burpees, sit-ups, step-ups, and wall ball shots. At each training session, the participant performed 3–5 of the aforementioned resistance exercises, with 10–15 repetitions and 2–4 sets. Once participants could complete all repetitions, the workload was increased for the following session.

Still, the main advantage of exercise was not, as you may now falsely expect due to the ~100% increase in energy deficit, a significantly increased loss of body fat (the latter did not double and that must not surprise you!). Neither was it a powerful increase in insulin sensitivity (HOMA-IR), which increased in both groups similarly (45% | p<0.001). Yeah, and even the extra 0.2% decrease in HbA1c, the sugar coating on the subjects' red blood cells  (-0.9% in diet only, -1.1% in diet + exercise), is not the main reason you must not miss your workouts while dieting (paleo-style or not ;-).

Figure 2: Fat mass (a), insulin sensitivity (b), and cardiovascular fitness (c and d) during 12 weeks following either a Paleolithic diet with a supervised exercise program (PD-EX) or a Paleolithic diet combined with general exercise recommendations (PD). Boxes represent medians and IQRs, whiskers represent the most extreme values besides outliers, and filled circles represent outliers (>1.5 IQR); **p<0 .01="" 2016="" p="" td="" tten.="">

So why are workouts important, then? It's the increased fitness, as evidenced by the PD-EX exclusive increase in maximum oxygen uptake (0.2 L/min) and the conservation of lean mass, which reached statistical significance (1.2kg in PD-EX vs. 2.6 kg in PD) only in the male subjects (p<0.05 for the difference between intervention groups), however (it is well possible that this is due to a lack of protein in the women's diet, cf. bottom line), that made / makes exercise (esp. resistance training) so valuable while dieting... this and another thing, the abstract of the study does not appreciate, because it did not reach statistical significance: The increase in relative resting energy expenditure (REE), the scientists observed in the PD-EX group (this adds to the extra energy expenditure during workouts, by the way!). While the relative REE didn't change in the PD group, it increased by a(n over the long-term) potentially relevant (but statistically non-significant) 3% in the PD-EX group - an effect that more than countered the nasty reduction in REE scientists still hold responsible for the yoyo-effect most "biggest losers" experience after successfully losing weight.

Is this the first paleo study? Even though, the number is still low, this is not the first one. In 2009, already, Jönssen et al. reported that "a 3-month study period, a paleolithic diet improved glycemic control and several cardiovascular risk factors compared to a diabetes diet in patients with type 2 diabetes" (Jönssen. 2009). In 2013, the same authors found that a "Paleolithic diet is more satiating per calorie than a diabetes diet in patients with type 2 dia-betes [and that t]he Paleolithic diet was seen as instrumental in weight loss, albeit it was difficult to adhere to" (Jönssen. 2013) - a result they had previously observed in patients with heart disease, too, when they compared a paleo to a Mediterranean diet (Jönssen. 2010), which also improve glucose tolerance less effectively than the paleo diet in said subject group (Lindeberg. 2007). Furthermore, studies in healthy individiuals Frassetto et al. (2015) like Österdahl et al. report that even "a short-term intervention showed some favourable effects by the diet" (Österdahl. 2008) such as weight loss, waist reductions and an improved quality of the diet and improved "BP [blood pressure] and glucose tolerance, decreases insulin secretion, increases insulin sensitivity and improves lipid profiles without weight loss" (Frassetto. 2015). In view of the fact that the less than a handful of long-term (>1 year), studies similar benefits when comparing paleo to other recommended diets, such as the Nordic Nutrition Recommendations in Mellbert et al. (2014) also show "greater beneficial effects" (e.g. fat mass, abdominal obesity and triglyceride levels just as they were observed by Ryberg, et al. in 2013) for the paleo diet(s), one could argue that the evidence in favor of paleo dieting in health and disease is slowly accumulating.

Eventually, diet is king, ... and that, just like the fact that doubling the energy deficit you have on paper won't double the loss of fat mass, shouldn't be news to you. That doesn't mean that dieting with exercise would not increase the loss of fat mass, but what is more important is that it helped the subjects - at least the male ones - maintain significantly more lean mass (=muscle and organ mass, which also affects you REE!).

Whether the failure of the workout to produce significant lean mass maintenance in the women was due to their sex, their hormonal status (the females included in the study were postmenopausal) or the fact that they gravitated to eat less protein (this is speculative, since the study does not provides sex-specific intakes) cannot be said. Even in the men, the lean mass loss is yet large enough to speculate that we'd have seen sign. less muscle loss with higher protein intakes. After all, the 79g the subjects in the PED-EX group consumed on a daily basis amount to only 0,84g protein per kg of body weight. This has repeatedly been shown to be too little for older individuals - even if they were not dieting. A follow up to the study which includes (a) simply more protein or (b) an extra protein shake after the workouts that would bump the subjects' total protein intake into the ~1.6-2.0g/kg region would thus be something I'd like to see in the (not so distant) future.

As long as said study will not have been done, though (something tells me that it won't ;-), you can still reference Otten's study as evidence that you can effectively lose weight without cereals, dairy products, and legumes... I have to admit, though, that I suspect that especially the latter two of these "forbidden" foods would rather have augmented, not messed with the improvements in body composition Otten et al. observed in the study at hand | Comment!

References:

• Frassetto, Lynda A., et al. "Metabolic and physiologic improvements from consuming a paleolithic, hunter-gatherer type diet." European journal of clinical nutrition 63.8 (2009): 947-955.
• Jönsson, Tommy, et al. "Beneficial effects of a Paleolithic diet on cardiovascular risk factors in type 2 diabetes: a randomized cross-over pilot study." Cardiovasc Diabetol 8.35 (2009): 1-14.
• Jönsson, Tommy, et al. "A paleolithic diet is more satiating per calorie than a mediterranean-like diet in individuals with ischemic heart disease." Nutrition & metabolism 7.1 (2010): 1.
• Jönsson, Tommy, et al. "Subjective satiety and other experiences of a Paleolithic diet compared to a diabetes diet in patients with type 2 diabetes." Nutrition journal 12.1 (2013): 1.
• Mellberg, Caroline, et al. "Long-term effects of a palaeolithic-type diet in obese postmenopausal women: a two-year randomized trial." European journal of clinical nutrition 68.3 (2014): 350.
• Lindeberg, Staffan, et al. "A Palaeolithic diet improves glucose tolerance more than a Mediterranean-like diet in individuals with ischaemic heart disease." Diabetologia 50.9 (2007): 1795-1807.
• Österdahl, M., et al. "Effects of a short-term intervention with a paleolithic diet in healthy volunteers." European journal of clinical nutrition 62.5 (2008): 682-685.
• Otten, J, et al. "Effects of a Paleolithic diet with and without supervised exercise on fat mass, insulin sensitivity, and glycemic control: a randomized controlled trial in individuals with type 2 diabetes." Diabetes/Metabolism Research and Reviews (2016 |Accepted Article). doi: 10.1002/dmrr.2828
• Ryberg, Mats, et al. "A Palaeolithic‐type diet causes strong tissue‐specific effects on ectopic fat deposition in obese postmenopausal women." Journal of Internal medicine 274.1 (2013): 67-76.

Caffeine, Exercise and Your Sleep: The Link Could be Sign. Different From What You Expect - Sleep Better W/ Caffeine?

Caffeine, Exercise and Your Sleep: The Link Could be Sign. Different From What You Expect - Sleep Better W/ Caffeine?

caffeine coffee ergogenic exercise health sleep sleep duration sleep quality stimulants

Coffee and exercise both effect sleep, but their effects don't simply add up. The study at hand does yet suggest that your preworkout coffee won't ruin your sleep.

I have to admit, the following are not results of peer-reviewed research, but with a 2x2 week design, participants being randomized to exercise (4 workouts per week) or be sedentary and to consume caffeine or placebo prior to exercise or rest, it looks methodologically complex, but sound and, more importantly, interesting enough to make it into the SuppVersity news ... I mean, it's about coffee ;-)

With that being said, the scientists, who were hopefully less biased than I am, required their subjects to refrain from any extra regular physical activity and or coffee / caffeinated beverage consumption outside of the conditioning/treatment sessions, in which they didn't drink coffee, but 350-mL of Gatorade with or without a rel. low dose of 3mg/kg caffeine.

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The authors' data analysis involved the usual mixed analysis of variance with treatment (placebo or caffeine) and condition (exercise or sedentary) as between subjects factors. In addition, time as the repeated measure, and the subjects' usual caffeine intake and BMI were included as covariates.

Figure 1: Mean sleep duration (h) in the different arms / phases of the 2x2 week RCT (O'Brien. 2016).

As the data in Figure 1 tells you, the statistical analysis yielded an independent main effect of
condition (sedentary/exercise) on the number of hours the subjects actually slept (this is not "time spent in bed"). In that, it did matter, whether the subjects worked with or without caffeine, but both, the effects of exercise (SED vs. EX | Figure 1), and as those of caffeine (see PLA vs. CAF | Figure 1) are not exactly what you probably expected:

• Effects of exercise - Subjects who exercised in the lab self-reported less time (hours) sleeping [F(1,18) = 4.5, p = 0.049] compared to sedentary. In that, there was a trend for an independent effect of treatment (placebo/caffeine) on hours slept (p = 0.08),
• Effects of caffeine - Subjects who received placebo self-reported less time (hours) sleeping compared those who received caffeine (that was not what you'd expect based on previous evidence). In that, there were no interactions by usual caffeine intake.

Now, one's sleep duration is only one out of several parameters that will determine whether or not you rise and shine refreshed; plus, since all subjects had average sleep times in the "green zone" of 6.5-8h per night, they were all sleeping enough - irrespective of exercise and/or caffeine. The parameter of actual interest is thus the subjects' subjective sleep quality and its relationship to their perceived tiredness in the AM / over 24h, which were both assessed with questionnaires in the study at hand.

Figure 2: Sleep quality and perceived tiredness over the course of the 2x2 week RCT (O'Brien. 2016).

For the former, i.e. the subjects' sleep quality, the data in Figure 2 signifies that here was a significant time x treatment x condition interaction on overall sleep quality [F(11,198) = 1.92; p = 0.038]. In that,  the subjects' sleep quality decreased over time in subjects who exercised compared to condition controls (sedentary). In contrast to what you'd expect, though, it were not the subjects who worked out and consumed caffeine who had the lowest sleep quality, but those "who exercised and received placebo [who] had the lowest overall average sleep quality" (O'Brien. 2016).

What may come as a surprise is that this decline in sleep quality had no effect on the subjects' perceived tiredness (Figure 2, right), which showed a main effect of time for ‘Body Feels Tired’ [F(11, 154) = 2.1; p = 0.026], but no treatment (placebo/caffeine) or condition (sedentary/exercise) interactions - which is unquestionably odd. About as odd, as the misleading statement that "[p]oorest sleep quality ratings associated with caffeine and exercise" (O'Brien. 2016) from the scientists' own summary of the results. Now, don't get me wrong. This statement is correct, but only if we are talking about the individual effects of exercise / sedentary and caffeine / placebo, on their own. The way O'Brien et al. phrased it, does however appear to suggest that the subjects' sleep was worst during the exercise + caffeine trials... Now, that, in turn, is what you probably expected the study to show, but another brief glance at the data in Figure 2 (left) confirms: caffeine did not mess with the subjects' sleep quality. In fact, the group with the most stable sleep quality are the sedentary coffee drinkers . eventually, you could thus argue that they had the best sleep quality!

High Dose Caffeine Restores Insulin Sensitivity and Limits Sugar-Induced Total + Visceral Fat Gain . That's in contrast to the still prevalent message that caffeine would ruin your insulin sensitivity | more

Bottom line: As the authors point out, "[e]xercise and caffeine did not have the hypothesized results on sleep quality and duration" (O'Brien. 2016). Instead of improving the sleep quality of the subjects, as it has been observed previously in both, middle-aged and older adults (Yang. 2012) and young healthy sleepers (Flausino. 2012), exercise clearly reduced the young subjects' sleep quality in the study at hand. As O'Brien et al. point out, this may have been a function of the novelty of the exercise and subsequent "physical discomfort that disrupted sleep quality and duration" of the previously untrained subjects in the study at hand, so that the results would change over time / be different if the study had used trained individuals.

Another important subject characteristic that may have "messed" with the results were the sujects' individual habitual caffeine consumption (100mg/day on average). Even though their habitual intakes were low, the fact that caffeine did not, as it did in previous studies, per se mess with the subjects' sleep quality, but rather improved it, could, as O'Brien et al. suggest, be due to "[w]ithdrawal reversal" of which the scientist argue that it appears to be "the primary action mechanism of caffeine [in the study at hand]" (O'Brien. 2016). Practically speaking, this would mean that "[r]eversing [the] negative state [of being on caffeine withdrawal] through caffeine administration improved [not decreased the subjects'] sleep quality and duration" (O'Brien. 2016 | my emphasis). How realistic this assumption is does yet appear questionable, with std. deviations of <50mg/day, the subjects don't seem to be caffeine junkies and with a dosage of only 3mg/kg per day (all subjects were normal weight, so that's probably in the 200-300mg range) switching from a caffeine to a no-caffeine group in the 2nd of the 2x2 week phases doesn't appear to be likely to induce significant "caffeine withdrawal", either. I am thus doubly curious to see the (hopefully) full dataset, when this intriguing study is eventually published (also because the the caption of Figure 1 in the "FT" says that there was no interaction with habitual caffeine intake for sleep duration, at least). In the mean time, I'd suggest you simply listen to your body. The effects of exercise and caffeine on one's sleep are, after all, just as so many things, highly individual | Comment!

References:

• O’Brien, E, et al. "Caffeine and Exercise Affect Sleep Duration, Quality and Perceived Tiredness." Department of Exercise and Nutrition Sciences---University at Buffalo, Buffalo, NY (Poster presentation).
• Yang, Pei-Yu, et al. "Exercise training improves sleep quality in middle-aged and older adults with sleep problems: a systematic review." Journal of physiotherapy 58.3 (2012): 157-163.

Protein Oxidation 101: 8 Simple Rules to Minimize PROTOX and Maximize the Proven Benefits of High(er) Protein Diets

Protein Oxidation 101: 8 Simple Rules to Minimize PROTOX and Maximize the Proven Benefits of High(er) Protein Diets

carbonylation dairy health high meat high protein high protein diet meat oxidation oxidative stress protein carbonyls protein oxidation protein powders protein-carbonyls PROTOX whey

You're not going to like it, but not all of the protein foods in this photo deserve the attribute "SuppVersity Suggested"

I usually try to keep my promises,... even if this means hours of research and ending up with the conclusion that "more research is necessary"... and no, you don't have to worry, there's more than that in the following ~4500 words + 45 references (not including those I didn't copy from the reviews I cite): plenty of information about the effects of cooking, storage, temperature changes, physical processing, and - you're lucky - a preliminary list of 8 tips / rules (and short explanations) that will help you minimize the amount of oxidized protein in your diet, without having to cut back on the intake of your beloved protein ;-)

For those of you who are now wondering PROTOX is / are and why they are (literally) a matter of life or death, I suggest you go back to my previous article about the (ill) health effects of oxidized dietary (!) proteins from Thursday, May 19, 2016 (read the article | as always, for free!).

This is not an anti-high-protein article. It is one arguing in favor of "treating your protein right"

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In view of the fact that this article got longer than the average "101" article, I'd suggest that anyone who is in a hurry fast forward to the list of eight simple rules I announced in the title of this article. You can bookmark the rest for later, print it to read it in bed or simply rely on my interpretation of the implications of what we know about the various ways processing and storage can damage proteins :

• Cooking, frying, baking, i.e. heat treatment(s), in general - While you don't have to eat your meat, fish and dairy raw, those of you who "fry their proteins to death" and eat their steak well-done are at a higher risk of exposing themselves to exuberant amounts of oxidized proteins than the rare steak conconnoisseurs.
  
  While the number of studies testing for protein oxidation in meats during cooking is higher than those on any other protein source, their number is, compared to the one of studies investigating the oxidation of fats and cholesterol in meat products, still low and their significance is crippled by the use of either inappropriate markers of protein oxidation or different markers that make it virtually impossible to compare the results of one study to another.
  
  An example of the initially mentioned problem, i.e. the use of inappropriate markers of protein oxidation, would be the 1997 study on the effects of different cooking methods on some lipid and protein components of hamburgers by Rodriguez-Estrada, M. T., et al. (1997). Their use of free form amino acids as marker of protein oxidation suffers from the presence of the latter in raw meat and their drip loss during cooking.
  

  

  Figure 1: In contrast to the amount of free amino acids, the formation of Schiff bases provides reliable information about the oxidation of protein during e.g. cooking (data from Gatellier. 2010).

  A much better way to estimate the degree of protein oxidation in meat and other high protein foods is the formation / presence of Schiff bases. The latter are precursors to maillard products of which studies indicate that they have divergent effects on human health: with some of them being implicated in the development of diabetes mellitus, cardiovascular complications, and Alzheimer's disease and others ostensibly helping with gut health, inflammation, and chemoprevention (the benefits appear to be mediated by hormesis or the effect of these molecules on the make-up of your microbiome | Smith. 1994; Somoza. 2005; Tuohy. 2006; Tessier. 2012). Measuring these byproducts of reactions between proteins and aldehydic products, as it was done by Gatellier, et al. (2010 | see data in Figure 1), provides significantly more reliable information about the degree of protein oxidation in foods than the measurement of the amount of free amino acids which would suggest that raw meat was more oxidized than cooked meat (cf. Rodriguez-Estrada. 1997), because the drip loss of amino acids is falsely interpreted as a reduction in protein oxidation compared to the raw product. That this is not the case and heating meat and other high protein foods will increase, not decrease the amount of oxidized proteins can be seen in the data from Gatellier, et al. in Figure 1.
  
  Furthermore, Gatellier's and other studies indicate that the formation of protein oxides which starts at relatively low temperatures of only >65°C does not begin to really take off before temperatures of 123-207°C - temperatures as you would see them if you fry your foods and can be reduced (albeit not significantly | 1300% increase vs 3500% increase | cf. Figure 2) if the cattle has been fed anti-oxidant rich diets.
  

  

  Figure 2: Effect of diet and cooking parameters on protein oxidative modifications (Gatellier. 2010).

  This is not surprising, as it has long been established that increases in lipoxidation products go hand in hand with increased oxidative damage to proteins (Requena. 1996). Any diet that would modify the concentration of certain lipids and lipid protecting antioxidants (like vitamin E) will thus change both, the oxidation of fats and proteins in high protein foods. The reverse applies to pro-oxidant diets (e.g. with rancid oils), like the one Zhang et al. (2010) used in broiler chickens whose breast meat would then show increased levels of oxidized proteins.
  
  You must not forget, however, that the data in Figure 1 also shows that even the quality L+R meat is not fully protected from oxidation when it is heated at high(er) temperatures for more than 60 seconds - and that's something that is going to happen even for the most bloody (non-raw) steak. "t "and "T", i.e. time and temperature, are thus not the only, but the most significant determinants of  protein oxidative modifications (cf. Figure 3).

An increased drip loss suggest increased protein oxidation: It's not just annoying if your meat weights only half of what it weighed before cooking, it is also an albeit not 100% reliable indicator or, I should say, correlate of increased protein oxidation. That's at least what a 2012 study by Traore et al. indicates: in said study, the researchers analyzed the effects of heat treatments on meat from the M. longissimus thoracis from Galia and Redone pigs. What they found was a striking and statistically significant correlation between the presence and level of oxidized proteins and the drip loss during cooking / frying. This observation does not only suggesting a possibly reduced ability of oxidized proteins to retain water, but also the possibility of using the drip loss, which is a marker of meat quality, anyways, as an easily accessible indicator / estimate for protein oxidation.

• 

  Figure 3: Time matters, but heat, too - Markers of protein oxidation in meat exposed to 100°C (grey) and 270°C for the time in minutes indicated on the x-axes (Santé-Lhoutellier. 2008).

  In fact, previous research confirms and underli-nes the importance of time and tempera-ture and indicates that even at temperatures of only 100°C, the level of oxidation products in meat proteins will double within just 5 minutes.
  
  When the time of exposure is short, the corresponding +200% increase in carbonyls (a marker of PROTOX | see Figure 3) that occurs at low temperatures is allegedly relatively small. If you are into slow-cooking your meats at "low" temperatures for several minutes, any low temp. advantage would be lost, though.
• Traditional processing methods to increase the storage time like dry-curing or fermentation - In contrast to the effects of heat treatment(s), the ones of other common processing methods are comparably under-researched. What we do know, however, is that dry-curing meats (and probably dry-aging, too - although a study on that has still to be done, to answer your Facebook question honestly, Matthew) can lead to sign. hydrolytic degradation of proteins (Toldrá, 1998). Furthermore, recent studies indicate that meat proteins will also undergo different, often more intense (compared to proteolysis) oxidative reactions during dry curing (Estévez. 2011).
  

  

  Figure 4: Carbonyl content (nmoles/mg protein) in longissimus dorsi (unprocessed) and dry-cured loins from different pigs on diefferent diets; % indicates relative increase in protein oxidation (Ventanas. 2006).

  Studies carried out by Ventanas et al. (2006 & 2007) prove the presence of significant amounts of protein carbonyls in dry-cured loins and hams  - a process of which the researchers study shows that it was, once again, linked to the lipid oxidative reactions that occur during curing. 

Steaming uses temps >60°C where proteins start to oxidize and steaming takes its time. It is thus not per se safe.

Steaming is not the solution: Unfortunately, detailed comparisons of the effects of steaming, microwave cooking, smoking, grilling, frying, and other cooking methods are not available - temperature level and duration of heat treatment have been the major focus in the literature and the results indicate that even "low" temperatures, such as the 100°C of steam will induce significant damage to meat, poultry or fish proteins during the 5-10 minutes they have to be exposed to the thermic treatment; that's because even at temperatures only slightly >60 °C can cause the oxidative cleavage of the porphyrin ring, which in turn will result in an increased release of heme iron, which has been shown to drive both, lipid and protein oxidation (Miller. 1994).

• The hams, which are subjected to longer and more severe drying conditions, were found to have considerably larger amounts of protein carbonyls than the loins (≈ 9 nmol/mg protein vs. ≈ 1.3 nmol/mg protein). The manufacture of dry-cured meats involves a lengthy process (up to 36 months for Iberian dry-cured hams) and several operations such as salting, post-salting, drying and cellar (Ventanas. 2007). Little is known about the impact of each step on the onset and intensity of the oxidative reactions affecting to meat proteins. What studies have shown, however, is that ..

  "[s]alting, which is a common operation for the manufacture of numerous meat products, may have an impact on protein carbonylation. The addition of sodium chloride has an impact on the ionic strength of the environment which in turn, affects the degree of assembly of MP (Wick, 1999) their exposure to pro-oxidants and hence, their susceptibility to carbonylation (Montero, Giménez, Pérez-Mateos, & Gómez-Guillén, 2005). In addition, several authors have proposed that NaCl could enhance the activity of Fe3+ or that Cl− derived from NaCl would improve the solubility of such ion, hence, stimulating their pro-oxidant effects (Kanner et al., 1991 and Osinchak et al., 1992)" (Estévez. 2011).

  Accordingly, you can assume that the protein oxidation increases with the amount of salt that's used when meat or, as the study by Osinchak et al. shows, fish is cured - an interesting observation that should remind you of the link between high salt intakes and heart disease, of which said link suggests that it could at least partly be mediated by the effect of salt on protein oxidation in processed meats and other high protein foods.
• Storage, cooling, freezing, high pressure and irradiation to reduce bacterial contamination, and packaging - You already know that cooked protein products have increased carbonyl levels compared to raw samples (1–3 nmol/mg protein in raw vs. 5 nmol/mg protein in cooked products), but the heat exposure is not the only threat to the proteins' integrity: cutting, mincing, and all the other processing steps protein foods undergo will likewise make significant contributions to the formation of protein carbonyls and other processes of protein oxidation.
  

  

  Figure 5: Evolution of protein oxidation in liver pâtés from Iberian and white pigs (note the difference that exists even before storage) under refrigerated storage (Estévez & Cava. 2004).

  In contrast to the former processing steps, the effects of subsequent refrigerated storage, has also been extensively studied - with disconcerting results, namely significant increases in the concentration and oxygenation of non-heme iron and thus the extent of lipid and protein oxidation (Estévez & Cava, 2004) which can render certain meat product, like liver pâtés that are refrigerated for several months quasi non-suitable for human consumption (see Figure 5) and will still significantly increase the protein oxidation of other less processed foods w/ lower amounts of iron such as chicken legs and breasts (see Figure 6)
  

  

  Figure 6: Changes in carbonyl content in chicken (a) leg meat and (b) breast meat as affected by freezing temperature and 6 months of storage at different freezing temperatures (Soyer. 2010).

  Now, freezing, which is particularly damaging if it is done at rather low temperatures at home (cf. Figure 6), is not the only storage method that increases the protein carbonyl content of meat and other high protein foods. In fact, storage per se will trigger natural biochemical processes that will inevitably favor protein oxidation. In that, decreases in pH and increases in the concentration of H+ ions are only one of various drivers of oxidative stress that can increase the susceptibility to protein carbonylation / oxidation - processes that will be further accelerated when meat is irradiated (common practice in the US meat industry) to kill bacteria (compare the size of the orange with the blue bars in Figure 7).
  

  

  Figure 7: Effect of Storage Time (12 Days) on Nonirradiated and Irradiated Raw Chicken Breast Meats Stored at 5 °C on Carbonyl Content as Lipid (in µmol Acetophenone/10 g Meat | Rababah. 2004)

  It is thus not surprising that Martinaud, et al. (1997) observed a significant increase of the carbonyl content in meat from beef longissimus lumborum and diaphragma pedialis muscles: from 3.1 to 5.1 nmol/mg protein and from 4.8 to 6.9 nmol/mg protein, respectively, during only 10 days of chill storage. Subsequent studies confirmed the occurrence of protein carbonylation during aging/chill storage of beef, pork, poultry, turkey, lamb, rhea, ostrich meat and eggs, in which Liu et al. (2009) found a 60% increase in egg white and a 41% increase in egg yolk protein oxidation.

Make no mistake: Eggs are healthy!.

Speaking of eggs, ... the change of the textural and structural quality of egg yolk and white upon heating is not the only change egg proteins will undergo while being heated at temperatures above 70 °C at atmospheric pressure or being exposed to high pressure of >500−600 MPa which will trigger the oxidative formation of disulfide bonds among the egg proteins (Van der Plancken. 2005 & 2006). That doesn't change my conclusion that the presence of oxysterols (oxidized cholesterol) is probably of greater health relevance than the lack of heat stability of egg proteins.

• Due to the large variability of the data reported by different authors for the amount of protein carbonyls in similar meat samples analyzed, it is unfortunately not possible to infer general patterns (Estévez. 2011) - that's also because the "extent of protein carbonylation is highly dependent on the origin of the meat, type of muscle, species and the storage [and feeding] conditions" (Estévez. 2011).
  
  Another thing that appears to be proven is the fact that beef is significantly susceptible to protein carbonylation than pork - a fact scientists ascribe to the noticeably larger amounts of iron and myoglobin in cattle muscles (Lund. 2007a,b). Accordingly, it can hardly surprise you that a similarly lower propensity for protein oxidation has been found by Mercier et al. (1998) when they compared beef and turkey meat.
  

  

  Figure 8: Determinants of the susceptibility of meat(s) and poultry to protein oxidation.

  If the differences are in fact, as the scientists argue, due to the different amounts of iron and myoglobin in various muscle meats, it is not just logical that (a) beef is more susceptible to protein oxidation than pork, but also that (b) pork more prone to protein oxidation than poultry and that (c) gylcolytic, low fat, low myoglobin (strength) type muscle meat is less susceptible to carbonylation than oxidative, high fat, high myoglobin (endurance type) muscle meat (Filgueras et al., 2010) - how oxidized the protein in your meats is will thus depend on both, species and the cuts you choose (+ other previously discussed factors).
  

  

  Figure 9: Levels of AAS (a) and GGS (b) in dry-cured ham as analysed by LC–MS. Mean values correspond to area units from the peak integration of EIC for [M+H]+267 (AAS–ABA) and for [M+H]+253 (GGS–ABA) and corrected considering the total protein content of each batch. Different letters on the bars denote statistical differences (p < 0.05) amongst means. IF (intact format), CSF (conventional-sliced format) and ASF (alternative-sliced format - which also influence markers of protein oxid. | Fuentes. 2010).

  How significant the effects of other emerging processing technologies such as the application of hydrostatic pressure, which is used as an alternative to irradiation and pasteurization to kill bacteria, eventually is, has not yet been fully elucidates. While studies by Cava et al. (2009) and Fuentes et al. (2010) indicate that the application of high pressure can causes a significant increase on the amount of specific protein carbonyls, α-aminoadipic and γ-glutamic semialdehydes (AAS and GGS), "as a likely result of physico-chemical changes induced by hydrostatic pressure including tissue disruption and increase of free catalytic iron" (Estévez. 2011), the evidence is far from being conclusive and the pressure in your pressure cooker (~100 MPa or 15 psi) is 6 times lower than the 600 MPa used by Cava et al. (2009) and applied for a 100x shorter time periods than it took to produce significant protein oxidation in Cava et al. (2009) at 300 MPa. So the pressure in a pressure cooker is probably less of an issue than the time your meats and other protein sources will spend in it at high temperatures.
  
  The same goes for the commonly used modified atmosphere packaging (MAP), which has been shown to contribute to increased myosin cross-links, and increased protein carbonyls especially if the "modified atmosphere" is high in oxygen (70% to 80% | Lund 2007a,b) - a condition that has been shown to reduce the formation of thiol groups, i.e. fat oxidation, but has the obvious downside of increasing protein oxidation. Alternative packaging methods would be available, 100% nitrogen (results are mixed, e.g. Zanardi. 2002; Leygonie. 2011) or vacuum-packaging (effectively reduced protein oxidation during storage compared to MAP | Lagerstedt. 2011), for example, but just like the use of additives and ingredients with proven antioxidant capacity they are rarely used and more research is necessary to determine which of them offers the best protection to both proteins and fat.
• None-meat, -poultry or -fish proteins react similarly - While there's lots of research on protein oxidation in meats, studies on other food sources are scarce, but show similar trends with respect to processing-induced protein oxidation.
  
  In cheeses, for example, the lowest amounts of protein oxidation are found in "unripe" raw milk cheeses or cheese that was produced from milk that was semi-cooked or pasteurized at low (vs. high as in UHT milk) temperatures (Fedele. 2001).
  

  

  Figure 10: Protein-bound carbonyls (PC) in selected cheeses from differently processed milk, i.e. unheated, semi-cooked and cooked milk as a raw ingredient (Fedele. 2001).

  With the processing temperature, the amount of protein-bound carbonyls (PC), the previously discussed marker of protein oxidation, increases, significantly. In Figure 10 illustrates that pretty well, after all, the cheeses that were made from cooked milk all have sign. higher PC levels than those from raw or semi-cooked milk. Much in contrast to meats, the storage or, in the case of cheeses, ripening processes does not trigger a continuous increase in protein oxidation (data not shown): For Grana Padano, a cheese that's produced from cooked milk, for example, the rapid (+30%) increase in protein carbonyls in the first 1-3 months of ripening does not continue and the level of PCs remains relatively stable for the rest of the several months period spanned by the study by Fedele et al.
  
  

  

  Figure 11: Kinetics of protein carbonyl generation by UV or fluorescent photooxidation. Protein carbonyls were determined in milk exposed to UV or fluorescent (FL) light, as a function of time of exposure to radiation. ■ = whole milk (WM) exposed to FL light; ● = skim milk (SM) exposed to FL light; □ = WM exposed to UV light; and ◯ = SM exposed to UV light (Scheidegger. 2010)

  Next to high temperature exposure (and yes, there will be some protein oxidation during pasteurization, but the process is fast enough to make the effects negligible | Table 1), UV radiation is a se-cond threat to dairy proteins.
  
  As the data in Figure 11 goes to show you, it takes only a few hours under a 15W UV lamp and/or a similarly "weak" fluorescent lamp to trigger rapid increases in protein oxidation in "milk", or rather what Scheidegger, et al. call milk, i.e. a liquid that was produced from water with commercially processed spray-dried whole milk powder, of which you can already expect that it has sign. higher baseline PC levels than regular milk.
  
  To deliver milk in regular, opaque tetra packs instead of the hipster glass bottles is thus a very good idea! Much in contrast to the use of regular or hypoallergic milk powders in processed and baby foods, the consumption of sweet condensed milk or its unsweetened alternative, evaporated milk.
  

  

  Table 1: Lysine damage in commercial milk samples (Mauron. 1990).

  Just like roller dried milk powder which is used in chocolates, and spray-dried lactose-hydrolized milk powder of which I have to admit that I don't know in which processed junkfoods it is used, the former food ingredients harbor significant amounts of blocked lysine, a previously discussed marker of protein oxidation that occurs relatively early during the oxidation process.
  
  Corresponding data for vegetable proteins is unfortunately not available. Even though vegetable proteins usually don't come with high amounts of easily oxidizable lysine (casein has a 2.0 ratio of lysine to arginine, soy's ratio is 0.9 | Kritchevsky. 1979), iron and myoglobin, soy, pea, hemp, bean and other vegan / vegetarian protein sources are not immune to processing, i.e. heat-, light-, and pressure-induced protein oxidation or the ongoing deterioration of their protein structure during storage. Whether these effects are strong enough to turn an originally antioxidant or neutral food protein into a pro-oxidant dietary ingredient, will yet need further clarification in realistic scenarios. Initial evidence that this could be the case comes from a 2015 study by Chen et al. who administered heat-oxidized soy protein to broiler chickens and observed that it would impair the chickens growth performance - probably as a result of negative effects on the digestive function. 

Don't be a fool: There's no evidence that protein powders are "adulterated" with exorbitant amounts of protein oxidation products; and, even more importantly, the currently available evidence in favor of the beneficial health effects of whey and co. clearly refute the practical health significance of the most likely existing amounts of protein oxidation products in the average protein powder.

Where's the info about whey, casein and other protein powders? In view of the fact that I can only report data that exists, it is very difficult for me to answer one of the most frequently asked questions I got after the publication of my original article on protein oxidation, namely: "What about my whey protein?"

What I have found out, though, is that whey proteins, like any other protein food, undergo heat-induced protein damage. For whey protein concentrates, Rector et al. report a rapid degradation of protein complexes when the protein is stored above the critical 60-65°C margin (Rector et al. used 80°C). Storage at 25°C for 1 year, on the other hand, resulted in polymerization of "only" 18% of the monomeric beta-lactoglobolins, and did not involve the formation of intermolecular cross-links, a characteristic feature of protein oxidation (Morr. 1993).

Whether the amount of protein oxidation products that certainly exist in casein, whey, soy, pea, and other protein powders is health-relevant, is therefore highly questionable. Furthermore, the well- and widely-established antioxidant effects of whey, which include, among other things, a reduction of protein oxidation in vivo (e.g. Haraguchi. 2011), would suggest that that the average whey protein doesn't just compensate, but over-compensate any potentially pro-oxidative effects of existing protein oxides by the anti-oxidant effects of its various antioxidant proteins and peptides (Tong. 2000; Peña‐Ramos. 2004; Peng. 2009).

In this context it may also be worth mentioning that a study by Fenaille et al. (2006), which investigated the protein-carbonyl (PC) levels in infant protein powder formulas, and is thus the study that comes closest to an analysis of PC levels in commercially available protein powders, found the amount of oxidized proteins to be not much different from those in unprocessed, cold-stored meat products. If certain quality standards during the production are met, it is thus unlikely that any potential worries you may have that protein powders could be much unhealthier than meat or other protein sources are warranted.

Wow, that was a lot of information on what you want to do or not do to reduce the oxidation of proteins. Since skipping on all protein containing foods and/or resorting only to raw meats, fish and milk is probably not an option. I have tried to use the previous information to phrase a few suggestions on what to do and not to do in order to limit your PROTOX exposure:

• 

  Figure 11: Influence of freeze–thaw cycles on TBARS (fat) & carnonyl (protein oxid.) in pork (Xia. 2009)

  buy, cook and eat fresh - it doesn't take heat to damage proteins, storage - even at very low temperatures - will also induce significant increases in protein oxidation; accordingly it makes sense to buy meat, poultry and fish fresh and to avoid storing and refrigerating them (esp. in view of the fact that storage / refrigeration in regular refrigerators will be more damaging than refrigeration of meats in much more efficient industrial refrigerators | Figure 11)
• avoid irradiated and or high pressure treated, industrially processed meats and prefer vacuum packaged meats over meats in modified atmosphere packaging w/ extra high oxygen levels (nitrogen is no problem) - the less processed and messed up the meat you buy, the less significant any further increases in protein oxidation you may induce at home will be; you should also ask your butcher if he already froze and thawed the allegedly "fresh" meat he offers - you may not believe it, but much of the "fresh" meat has actually been refrigerated and thawed at least once - especially, the more exotic cuts; also, vacuum packaging your meats at home makes as much sense as any other way of repackaging it to keep them fresh - none of them is going to be worse than simply putting the meat into the fridge in nothing but a simple plastic bag; pressure cooking is, as discussed previously probably not an issue (due to the comparatively low pressure), but the time your meats and other protein sources spend in the pressure cooker at relatively high temperatures could be
• use culinary herbs and spices - even though there is no data for each and every culinary herb and spice, the data that exists shows sign. reductions in protein, fatty acid oxidation and the formation of advanced glycation end-products (AGEs) for cloves, ground cinnamon, ground Jamaican allspice, apple pie spice, oregano, ground pumpkin pie spice, marjoram, sage, thyme, gourmet Italian tarragon, mint, rosemary, Italian poultry seasoning, turmeric, curry powder, chili powder, basil, nutmet, ginger, parsley, black pepper, and rosemary (Dearlove. 2008; Haak. 2008);
  

  

  Figure 12: Protein hydrazones (expressed as nmol hydrazones/mg protein) gain during refrigeration of cooked burger patties with added fruit extracts and quercetin (Ganhão. 2010).

  and using high polyphenol oils like virgin olive oil for cooking and in marinades may further reduce the protein oxidation; speaking of which, marinades and or fillings and the addition made from antioxidant-rich fruits or plant products (e.g. onions, garlic and other high quercitin foods that mimic the addition of pure quercitin in Ganhao (2010) | Fig. 12) have also been shown to help minimize protein oxidation not just during cooking, but also during storage
• appreciate quality, non-cured meat - a high drip loss (meaning the weight of your meat is significantly reduce when you cook it) is a common marker of low meat quality and a correlate of high protein oxidation (Traore. 2012); the same goes for the loss of water that occurred way before you bought the meat during curing; and, yes, this means if there's a significant source of oxidized proteins in your diet, your beef jerky, bacon and other cured meats are the prime suspects - not only, but especially if they're also high in salt
• choose low(er) fat meats, poultry, fish, dairy and vegetable protein over iron- and myoglobin-laden red meats - it's not just the lower iron and myoglobin content of poultry and fish that makes them more resilient to protein oxidation, it is also their low(er) fat content, which reduces potential cross-reactions of oxidized fats with proteins; this does not mean that you cannot eat fatty cuts of red meat, at all, but there's more than just epidemiological evidence that the consumption of high amounts of processed and/or improperly stored or packaged red meat is problematic; not just, but also because of high levels of oxidized proteins

• 

  Don't do everything the print on these packs tells you: While you certainly don't want to eat these silica packets, you also don't want to throw them away before you emptied your protein tub - they will help to keep your protein (and other supplements) dry!

  store your protein powders cool, dry, and by any means not in the sun - there's no evidence that protein powders could be a major source of oxidized proteins in your diet - unless you do your best to make them go rancid by (a) rehydrating and storing them as an RTD, which will significantly increase the amount of volatile compounds even if the product is cooled (Park. 2016 / storing the protein with or at least not removing the silica gel packets (see photo on the right) may also help), (b) storing your protein powders in transparent containers in the sun, or (c) putting your protein tubs right next to a radiator or any other heat source
• prefer raw or pasteurized over ultra-high temperature processed (UHT) milk / dairy products - in contrast to what the scaremongering on the internet would suggest the short application of relatively low temperatures (72°C) during the pasteurization process does not induce significant damage to the protein-structure of dairy products; that's in contrast to UHT, which is done with at least 53°C higher temperatures and is notorious for its effects on the protein structure - an effect you will even taste and smell (Clare. 2005)
• go easy on the heat and keep the duration of any heat exposure short - "well-done" or "tar-black" are words you shouldn't be forced to use to describe your dietary protein sources; you also don't want to simmer your meats and other high protein foods at 100°C (or even >65°C) for hours or fool yourself to believe that steaming your fish at 100°C for 10 minutes was so much better (in terms of protein oxidation) than frying it for 2 minutes

Figure 13: A comparison of the initial and progressing oxidation of myoglobin (data expressed as % of total myoglobin) in intact and minced slices of beef gluteus medius samples (3 mm thick) that were observed by Ledward & MacFarlane observed in their 1971 study clearly suggests that (a) the process of mincing induced protein oxidation and (b) makes the meat more susceptible to progressing protein oxidation during storage.

Any Facebook-questions left? Yes, the thing about gelatin. Well, I have to admit that I neither know why one would even remotely consider consuming gelatin in amounts that would make it worth worrying about its oxidized protein content, nor whether gelatine even contains oxidized protein. In view of the fact that EAAs like lysin appear to promote protein oxidation just like iron and myoglobin, and considering the fact that gelatin contains neither of them in sign. amounts, I do yet have my doubts that gelatin is a sign. source of PROTOX in your diet, Gillian.

And Kirill, reliable data on the protein-carbonyl content of ground vs. non-ground beef is not available. The increased surface (=more oxygen exposure = iron / hemoglobin oxidation) and the heat that is produced when you mince it, would suggest ground beef will have higher higher amounts of oxidized proteins. Evidence that this hypothesis is accurate comes from a 1971 study by Ledward & MacFarlane who observed higher levels of oxidized myoglobin in minced vs. intact beef (see Figure 13).

Now, before I leave you totally confused about your diet, let me add this: Neither this, nor the previous article I wrote about the health effects of protein oxidation should be misunderstood as anti-protein propaganda. Protein oxidation is, after all, only one out of a myriad factors that will determine the health effects of your diet. If you know about it and take the previously outlined measures to keep your intake of oxidized proteins in check, there's no good reason to assume that the occurrence of oxidized proteins in animal, vegetable or other protein sources would be reason enough to sign. limit their intake, let alone avoid them altogether | Comment!

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