Was Conjugated LA from Dairy Products Missing in Prehistoric Times?

We have already discussed conjugated linoleic acids (CLA) here several times. Unlike ordinary linoleic acid (C18:2n-6), CLA are also C18:2 fatty acids, but they differ in the spacing of the double bonds along the carbon chain—they are closer together. They can also have different combinations of trans and cis double bonds. What they have in common is that they are less stable than linoleic acid and are more susceptible to peroxidation. They are therefore better sensors of oxidative stress. They more accurately reflect the state of metabolism and respond more sensitively to metabolic disturbances, breaking down more readily into various signaling molecules.

The most common source of CLA in our diet is milk fat. However, our bodies can also produce CLA from trans-vaccenic acid (TVA), which is also present in milk. There are animal studies showing that as little as 1% of calories from CLA in mice completely eliminates arterial plaque and restores fat metabolism, protects the liver, and more. How is that possible?

Is our milk the same as the milk our ancestors drank? Does anyone measure the CLA and TVA content of milk and dairy products? What if we are deficient in these fatty acids, just like this 30 thousand year old Venus of Dolní Věstonice, who lived in prehistoric inland Europe without access to marine fish, was likely deficient? Did the Venus have problems with fat metabolism because she did not have access to milk fat containing CLA and TVA? Or did that actually help her survive the inland winters more easily? What do you think?

I found an interesting human study that deals, among other things, with cheese quality. What makes it interesting is that it specifically examines CLA content and the health effects of cheeses enriched with CLA (and TVA, my note). Specifically, it measures HUFA levels—that is, the long-chain omega-3 polyunsaturated fatty acids (EPA and DHA)—and compares the effects of fish oil (FO) supplementation with the consumption of cheeses containing higher levels of CLA produced from the milk of cows (cow ENCH), sheep (sheep ENCH), and goats (goat ENCH) fed a specialized diet.

In other words, this was not a matter of adding CLA to the milk, but rather a completely natural enrichment resulting from different feed. However, this applied only to the sheep cheese used in the study, where improved grazing was implemented. In cows and goats, the increase in CLA content was achieved by supplementing the feed with sunflower or flaxseed oil. Interesting—that does not seem like a very natural feed. Nevertheless, it worked.

It appears that consuming just 50 g of cheese per day made from the milk of properly fed livestock could compensate for a lack of fish oil. Isn't that interesting?

So what was the fatty acid composition of these cheeses? If we add together the CLA and TVA content, we obtain 1.16 g per 50 g of cheese for the cow's milk cheese and as much as 1.52 g per 50 g of cheese for the goat cheese. That amounts to approximately 0.5% of daily caloric intake. Compared with standard industrially produced cheese, the CLA + TVA content is more than six times higher. That is already very comparable to the composition used in the above-mentioned study on the removal of arterial plaque using CLA.

It also appears that part of the mechanism of action of CLA involves activation of PPARα, and that it takes some time before the effect becomes evident. In this study, activation did not occur until one month after the dietary change.

Quotation

"Often, the nutritional guidelines for dietary fat intake rely on food fatty acid composition and, for example, a certain concentration of ALA is sufficient to claim that a food is a source of n-3. Our data clearly demonstrate that this is not the case and that an increase in circulating DHA may be efficiently achieved with different strategies, not only by supplying dietary n-3 FA. Interestingly, we found a significant decrease of PA, the major SFA in plasma, with the intake of ENCH cheeses. This might be surprising since cheese is sometimes negatively perceived because of its elevated SFA levels. It is known that dietary PA does not influence PA tissue levels in humans, as it is regulated by the balance between its main sources, i.e., diet and biosynthesis, through de novo lipogenesis (DNL), which is a very well conserved mechanism converting carbohydrates to lipids. We may hypothesize that ENCH cheeses may inhibit DNL probably by activating PPAR-α, thereby reducing the circulating PA levels."

End of quotation

While everyone focuses on the omega-3 fatty acid content or the omega-6/omega-3 ratio in dietary fats, I have not heard anyone place much importance on the CLA and TVA content of the diet—that is, in milk. Yet it appears that grazing and high-quality feed can multiply the content of these very important and protective fatty acids in milk fat, which may even compensate for the lack of fat from marine fish. A similar increase in DHA levels can also be observed after adding medium-chain triglycerides (MCT oil) to the diet.

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References:

Oxidation rate of conjugated linoleic acid and conjugated linolenic acid is slowed by triacylglycerol esterification and α-tocopherol

Dietary conjugated linoleic acid-enriched cheeses influence the levels of circulating n-3 highly unsaturated fatty acids in humans