Vitamins
More Vitamin A and D in Winter!
In winter, our body needs more vitamin A and vitamin D. Fatty fish and cod liver oil are the best natural sources—or modern supplements.
Vitamins
In winter, our body needs more vitamin A and vitamin D. Fatty fish and cod liver oil are the best natural sources—or modern supplements.
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Every year, at least for me (Chris), there's this phenomenon: as autumn approaches, I get a special craving for fish. Where does this come from? There could be many reasons. For example, the body wants to keep cell membranes—which are essentially made up of fatty acids—fluid. Because cold makes membranes stiffer. For cold-blooded animals, like fish in cold water, this is particularly relevant. So they store a high proportion of, for example, omega-3 fatty acids.
These fatty acids keep cell membranes fluid due to their chemical properties, and thus functional. Fatty fish is therefore the best omega-3 source for us. Perhaps our body also tries to keep cell—and especially mitochondrial membranes (mitochondria = the powerhouses of the cells)—more fluid and thus more functional. One possibility, anyway.
What many people don't realize, though, is that fatty fish is probably also the best vitamin D source in our diet. As soon as it becomes «dark» in late autumn—meaning UV exposure drops dramatically—we barely produce any vitamin D in our skin anymore. At the same time, vitamin D deficiency rates spike. The body probably wants to compensate for this and instinctively seeks out the best D source—fatty fish.
Wild salmon contains up to 1,000 IU per 100 g. That alone would reliably prevent deficiency. Indeed, studies repeatedly show that populations that eat a lot of fish are «outliers» when it comes to poor vitamin D status in winter. Scandinavia in particular performs especially well in this regard. In Norway, cod liver oil is recommended by public health authorities—and has been for 60 years. More than one-third of the entire population follows this recommendation, and about half of the elderly population takes it.
And it works like magic, at least according to a Norwegian study. Hold your breath: if you take cod liver oil during adolescence, your risk of developing multiple sclerosis drops by over 30%. A clear dose-response relationship was established—if you consume 60 (!) teaspoons of the oil per month, equivalent to approximately 600 to 2,000 IU of vitamin D daily (depending on the brand), the risk drops by as much as 50%.
Here's the crucial point: cod liver oil contains not just vitamin D, but also omega 3 and, importantly, vitamin A. In Switzerland and many Western countries, there's an increasingly absurd belief that vitamin A—real, animal-derived retinol—is something truly terrible. Imagine that: many pregnant women fear it, even though vitamin A is so important for cell differentiation of the embryo—vitamin A is actually converted into a hormone (retinoic acid). In Switzerland, like other Western countries, we're not just dealing with an omega-3 deficiency problem; we also face widespread vitamin D and vitamin A insufficiency.
This should particularly concern the cold-sensitive among us. Because in winter, the body mobilizes its vitamin A reserves. It transports vitamin A to fatty tissue and muscle tissue. There, it activates specific proteins found in mitochondria—these proteins, called uncoupling proteins, «uncouple» energy production in the mitochondria. This means energy from food or body fat is converted to heat. You literally «burn» your body fat for warmth, even within the fat tissue itself. This phenomenon is called «browning» of fat tissue. The fat tissue becomes metabolically reprogrammed so that in winter it behaves more like muscle.
So, to close the circle, we need one more crucial piece of information. Vitamin A and vitamin D always work together in the body. For vitamin A to work properly, it needs vitamin D—and vice versa. In winter, we have an increased need for both vitamins, at least from food sources. The sun no longer covers our vitamin D needs, and the cold dramatically increases vitamin A utilization. That's why our ancestors knew—why our body knows—that fish and fish liver can cover this need. Fortunately, we moderns don't need to eat fish to meet our requirements. Nowadays we have nutritional supplements, pure vitamins ;-)
In winter, we need more omega 3, more vitamin D, and more vitamin A. Starting right now. Either through food (fish, cod liver oil, liver, etc.) or through supplements.
