Travis
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@Travis, a few quick questions for you:
1. I would presume sheep yogurt is less immunogenic than cow yogurt but it’s also more expensive. What’s your opinion on yogurts, standard, Greek or sheep?
2. Does the lactic acid in yogurt need to be avoided?
3. Although not great, is skinless chicken breast is an acceptable protein? More acceptable than low fat fish?
Thanks and I look forward to your opinions
I. I had always like Greek the best, and had preferred to eat it on top of a pile of red grapes. But the lactic acid bacteria do have enzymes, and their proteolytic activity is catalyzed by the low pH environment consequent of their lactic acid. For instance: it only takes twenty-four hours for Lactobacillus sanfransiscensis to sufficiently hydrolzye wheat gluten to the point of non-immunogenicity, making a sourdough bread innocuous enough for celiac's to eat (but it's actually more likely that wheat lectins cause the physical damage, and not the immunogenic gliadins as commonly supposed). The effects of the fermentation cannot be disregarded, and I would say that the opiate effect of yogurt cannot be reliably inferred simply on account of its original casein content. So on account of Lactobacilli having a theoretical ability to degrade β-casomorphin, further investigation is required:
Nguyen, D. "Isotope dilution liquid chromatography–tandem mass spectrometry for simultaneous identification and quantification of beta-casomorphin 5 and beta-casomorphin 7 in yoghurt." Food chemistry (2014)
De Noni, I. "Occurrence of β-casomorphins 5 and 7 in commercial dairy products and in their digests following in vitro simulated gastro-intestinal digestion." Food chemistry (2010)
'Use of probiotic strains in fermented milk production may modify the peptide pattern in the final product and the potential release of β-casomorphins during stimulated gastric digestion could be affected as well. Nevertheless, a ultra-high temperature pasteurized milk fermented by the probiotic Lactobacillus GG strain and subsequently digested by pepsin and trypsin was not found to contain β-casomorphin-7 whilst only peptide sequences such as β-casomorphin-11 and β-casomorphin-4 were revealed.' ―de Noni
So exactly how the casein is degraded is somewhat stochastic, and only brie cheese had significant levels of pre-made β-casomorphin-7. Some bacterial strains do act on casein, yet no evidence I've seen as of yet indicates that the casomorphins are inactivated by them (that is, cleaved somewhere in the central region of Tyr–Pro–Phe–Pro–Gly (or YPFPG)—the core peptide region corresponding to amino acids № 75–82 of bovine β-casein as sequenced here).
And further complexifying the quality and quantity of peptide fragmentation, this initial peptide confetti—often created by multiple strains in just one cheese type—is further hydrolyzed by gastric trypsin and pepsin. Below is the result of thirty-one dairy products after simulated gastric digestion:
The cheeeses make everything else look insignificant, and even approach the values 'milk protein concentrate.' But they had only analyzed analyzed the dairy products for β-casomorphin-7 and β-casomorphin-5 (not present), and the longer β-casomorphin-11 is considered a proto-opiate.
'In the present work, pepsin and Corolase™ were used for SGID at the end of which none of the analysed dairy samples released BCM5.' ―de Noni
But β-casomorphin-4 certainly bioactive, and could potentially be present in yogurt. This species isn't always looked for, but perhaps it should be:
Matar, C. "β-casomorphin 4 from milk fermented by a mutant of Lactobacillus helveticus." International Dairy Journal (1996)
'Casomorphins are physiologically important peptides, that can be isolated from enzymatic digests of caseins (Brantl et al., 1979). Morphiceptin, which is an amide derivative of β-casomorphin-4 (Tyr-Pro-Phe-Pro), is a highly selective opioid agonist for both μ receptors in guinea pig ileum and morphine binding sites in rat brain (Chang et al., 1985); it is as potent as morphine (Ramabadran & Basinath, 1989).' ―Matar
'In order to grow in milk, lactic acid bacteria must have the ability to attack milk proteins by proteases and peptidases leading to limited proteolysis during the fermentation and to the release of peptides (Thomas & Pritchard, 1987). The breakdown of proline-rich proteins such as caseins often involves proline-specific peptidases; many lactobacilli possess this type of exopeptidase (Barnett, 1977).' ―Matar
'Numerous reports suggest that the biological activity of casomorphins is principally analgesic (Brantl et al., 1979), affecting the gastrointestinal tract and the central respiratory control mechanism (Ramabadran & Bansinath, 1989).' ―Matar
'This study demonstrated the presence of β-casomorphin l-4 in milk fermented by an X-PDAP-deficient mutant of Lactobacillus helveticus, suggesting a hitherto unexplored use of fermented milk as a potential source of bioactive peptides.'
But entire study was somewhat artificial, as he had mutated a strain of bacteria using ethyl methyl sulfonate from Sigma–Aldrich. The result was a mutant strain having protelytic enzymes of a different specificity as compared to the wild type, and this had shifted its hydrolytic propensity for specific peptide bonds:'In order to grow in milk, lactic acid bacteria must have the ability to attack milk proteins by proteases and peptidases leading to limited proteolysis during the fermentation and to the release of peptides (Thomas & Pritchard, 1987). The breakdown of proline-rich proteins such as caseins often involves proline-specific peptidases; many lactobacilli possess this type of exopeptidase (Barnett, 1977).' ―Matar
'Numerous reports suggest that the biological activity of casomorphins is principally analgesic (Brantl et al., 1979), affecting the gastrointestinal tract and the central respiratory control mechanism (Ramabadran & Bansinath, 1989).' ―Matar
'This study demonstrated the presence of β-casomorphin l-4 in milk fermented by an X-PDAP-deficient mutant of Lactobacillus helveticus, suggesting a hitherto unexplored use of fermented milk as a potential source of bioactive peptides.'
II. Someone sent me a private message about lactic acid a few months ago and I did some calculations. Let me see if I can find it.. .
I had read a few studies about lactic acid, did some math, and had concluded this (here is the link to the entire thread):
'I think it will cause about as much of a lactic acid spike as a mild jog. Our livers turn lactic acid back into glucose constantly, and physical exertion increases this. It's certainly not a stranger to normal metabolism. Ray Peat has a point in that it would theoretically occupy the liver with more work, but this does result in glucose so it's not a total loss.
My calculation indicates that a person at rest metabolizes 4× more lactic acid through their liver than what is found in 500 grams of generic commercial yogurt, per day.' ―Travis
My calculation indicates that a person at rest metabolizes 4× more lactic acid through their liver than what is found in 500 grams of generic commercial yogurt, per day.' ―Travis
III. The fish topic is somewhat controversial it seems because aquatic species have essentially no ω−6 fatty acids. These are certainly the worst ones and the sole precursor to the 1- and 2-series prostaglandins (via arachidonic acid). A person eating fish while also avoiding ω−6 fatty acids will have quite a bit more eicosapentaenoic acid at the sn-2 position of cell membrane phospholipids. This lipid will form the 3-series prostaglandins when released by trauma or phospholipase A₂, but these (as PGE) have only has about ¹⁄₄ of the carcinogenic activity as the 2-series prostaglandins (derived via ω−6); some researchers even characterized the 3-series as 'anti-inflammatory' or 'protective.' Eicosapentaenoic acid actually does appear beneficial in many studies, but perhaps this is only due to it's ability to displace the more dangerous arachidonic acid. Eicosapentaenoic acid could only be good to the extent that it's not arachidonic acid.
ω−6 dihomo-γ-linolenic acid (20∶3) + ONOO⁻ ⟶ cyclooxygenase ⟶ 1-series prostaglandins + ṄO
ω−6 arachidonic acid (20∶4) + ONOO⁻ ⟶ cyclooxygenase ⟶ 2-series prostaglandins + ṄO
ω−3 eicosapentaenoic acid (20∶5) + ONOO⁻ ⟶ cyclooxygenase ⟶ 3-series prostaglandins + ṄO
ω−6 arachidonic acid (20∶4) + ONOO⁻ ⟶ cyclooxygenase ⟶ 2-series prostaglandins + ṄO
ω−3 eicosapentaenoic acid (20∶5) + ONOO⁻ ⟶ cyclooxygenase ⟶ 3-series prostaglandins + ṄO
But ω−9 Mead acid is also a 20-carbon membrane lipid (20∶3), and this can displace both of them. And unlike arachidonic and eicosapentaenoic acid, this one is not a legitimate substrate for cyclooxygenase. While true that it forms a peroxide under the agency of that enzyme, this is not a endoperoxide ring which eponymously defines that enzyme (also called a cycloperoxide). This endoperoxide ring is also the defining feature of prostaglandin H, cyclooxygenase's main product and precursor to all others. Hence, it forms a leukotriene-type eicosanoid that is in no way similar to the prostaglandins. So even though eating fish would probably lead to improvements in a person replacing dark chicken or pork, for example, you cannot say that it would be better a better substitute for beef (unless acne should be the primary focus, in which case the increased sebum fluidity consequent of replacing beef with fish could help).
But since very few people avoid both fish and linleic acid, the presence of lipid profiles dominated by Mead acid is quite rare. Many coconut- and fish-eating islanders avoid ω−6 nearly entirely, which is easy for them since those temperate fatty acids hardly exist anywhere on their island. Vegetarians and vegans avoid fish, by definition, yet most of them consume substantial amounts of arachidonic acid precursors. The only mead acid dominated people would have to be those living near exclusively off coconut, fruit, and leaves. Beef and dairy are quite low, but they still could have the small amount necessary to prevent the synthesis of Mead acid. But as stated before, there isn't too much research on this; finding Mead acid in a person is a rare even these days. But if I were to guess, I'd say there are enough earlier studies to get a good idea of the extent you have to avoid ω−6 to fully deplete the cell membranes of arachidonic acid.