Choline
Choline may be the most critical nutrient for proper fat metabolism. 70–90% of Europeans carry genetic variants that reduce choline production, and deficiency can lead to fatty liver and altered muscle composition.
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Perhaps the most critical nutrient for proper fat metabolism? Which could it be? Let's get straight to the point: we're talking about choline. It's now considered an essential nutrient. The background is that the body can actually synthesize choline itself. But that's not enough. Moreover, 70–90% of Europeans carry genetic variants of the choline-synthesizing enzyme (PEMT) that significantly reduce its activity.
For decades—perhaps even more than half a century—we've known that choline deficiency makes the liver fatty. Without choline, the liver can't shed its fat. What you need to know: from choline, the body makes the phospholipid phosphatidylcholine, an essential component of our (cell) membranes. The transport vehicles that carry fat from the liver into the bloodstream are also surrounded by such a lipid layer. Without choline, these transport vehicles can't be built. Researchers long thought this was the reason for liver steatosis in choline deficiency. But that's only half the story.
As early as 1953, a groundbreaking study [source no longer available] was published in the world's leading scientific journal, Nature. It states:
"The lipotropic effect of choline has generally been interpreted on the assumption that fatty acids are transported out of the liver in the form of plasma phospholipids. The role of these compounds in the transport of fatty acids has, however, been questioned. The results presented here suggest strongly that choline acts by promoting the oxidation of fatty acids in the liver."
Aha! So choline might not work 'only' by helping transport fats out of the liver. These research findings pointed in a completely different direction: choline seemed to directly accelerate fatty acid oxidation in the liver. That means: without choline, the liver can't get rid of these fats. But what's actually going on? For example, this was investigated in 2014 in human liver cells [source no longer available]. Researchers overloaded cells with energy and observed what happened at different choline concentrations. The result:
Similar results were published in another study in 2019 [source no longer available]. There too, researchers examined what happened to liver cells overloaded with energy in the form of fatty acids (which in you and me come from dietary fat or stored body fat). They found: high concentrations of fatty acids shut down AMPK. Those in the know understand: without AMPK, the body can't become catabolic—that is, it can't burn fat. And again, choline proved extremely useful:
"These findings suggest that high-dose fatty acids (…) impair fat metabolism by affecting fatty acid oxidation, synthesis, and transport proteins. Choline (…) regulates central switches of fat metabolism through AMPK activation (…) to promote fat burning and transport in liver cells."
Isn't that fascinating? But there's more. Because choline doesn't just affect the activity of fat metabolism itself. Without choline, mitochondria don't function normally—and those are precisely the places where fatty acids are burned. We read in the same paper:
"There is increasing evidence for specific effects of choline on mitochondrial metabolism. A low choline status leads to altered composition of mitochondrial membranes, reduced mitochondrial function (membrane potential), reduced energy production, and impaired fatty acid oxidation in rats fed a choline-deficient diet."
That the whole picture has global implications was discussed at a symposium [source no longer available] by a Canadian research group led by researcher Laila Cigana Shenkel, who has herself published several studies on choline's effects. She concludes:
And if someone now wonders whether these mechanisms also apply specifically to muscle, where the body metabolizes most fatty acids anyway, well:
"Surprisingly, muscle cells also accumulated fat in the form of large lipid droplets. This fat comes from fatty acids in adipose tissue and is the result of slower fat metabolism in choline deficiency. In this study, for the first time it was established that choline availability affects the composition of muscle membrane lipids and cellular lipid metabolism, underscoring the importance of choline-rich food for good muscle function."
That means: it's not just the liver that gets fatty with low choline intake—the muscle does too. Aren't these sensational findings that could immediately and significantly impact your life? Because now comes the punchline: there are very few really good dietary sources of choline. Plant foods are generally very low in choline, except for a few exceptions (soy and sunflower lecithin). Choline comes primarily from animal sources, especially eggs and liver. One egg covers about 25% of the daily choline requirement. 100 g of liver covers the entire daily requirement.
Hunters and gatherers seem to understand the value of this treasure. [Source no longer available], where the Hadza are visited, you hear:
"Well, I don't know what's special about liver, but it seems to be true for every culture on this planet, whether in Siberia or Tanzania: liver is one of the first things you always eat. It's probably always the best part of the animal."
On the other hand, our society has recent dietary trends. Always these 'trends'. In any case, a 2019 article appeared [source no longer available] in the British Medical Journal with the headline: "Could we be overlooking a potential choline crisis in the United Kingdom?" The author Emma Derbyshire notes that choline intake falls short in virtually all Western nations and remarks: "This is (…) concerning, as current trends are clearly moving toward plant-based diets." … which could further intensify the possible widespread deficiency.
So it all comes full circle. Choline is essential. Better watch out… that you get enough of it. Because… choline deficiency is no laughing matter – here's [source no longer available].
To keep the newsletter from getting unnecessarily long, we're briefly linking today to the three studies or papers we read this week. Without summary.
