Why I am not in favor of supplementing with isolated vitamin D

During autumn and winter, it is more difficult to get our vitamin D needs met through sunshine. We would have to expose at least our arms and face to 30min of unprotected sunshine every day to cover our basic needs – and that simply is not going to happen during those colder times. So we have to rely on food and/or supplements. Vitamin D is a fat-soluble vitamin contained exclusively in animal fats. Best food sources for vitamin D are fatty fish, liver and butter from pastured animals. However, most people don’t eat enough of those foods either, which explains why a very high percentage of people are deficient, especially in winter. (Note that some vegetable milks are fortified with vitamin D2, but vitamin D2 is not bioavailable and our body cannot easily transform it into D3 either). While for kids vitamin D3 supplements are quite commonly recommended, for adults that is still much less the case, although it is slowly changing. Many people still go undiagnosed, unless they get a blood test done or visit their doctor for health concerns, such as depression, thyroid issues or recurrent infections. While too much vitamin D can also be harmful, I personally believe that most people would be well advised to supplement during winter (please have your blood levels checked prior to starting, they should be ideally between 35-60ng/mL). However, not all supplements are equally good!

The most common product people take here in Belgium is D-Cure. Even though there are different formulations and different dosage recommendations on the market, most people take D-cure bottles once every month or every two months. Those bottles provide a high dose (25.000 IU) of isolated vitamin D3 (cholecalciferol) per unit. While you might indeed feel a boost of energy the first times you take that product, there are several reasons why I am opposed to supplementing with isolated vitamin D3 in the long run.

Co-factors: In nature, nutrients do not come isolated, but always together with other nutrients and substances, with which they create synergies. This is why in general it is much better to get nutrients from food than from supplements, because it is very hard to reproduce the complexity of nutrition in a pill, taking into account all the interactions between the different nutrients. When it comes to vitamin D3, it needs (at least) vitamin A and vitamin K2 in order to be well assimilated, to avoid toxicity, and to make sure the calcium (that is better absorbed as a consequence of increased vitamin D) is deposited in your bones and not your arteries. Without those nutrients present in abundance, either in the diet, or added to the supplement, taking high doses of isolated vitamin D3 can create new nutrient imbalances and deficiencies, calcium deposits in the wrong place, and potentially even result in toxicity (if vitamin D3 is not well assimilated, it accumulates in your fat tissue).
Biochemical Individuality: Some products combine vitamin D3 with calcium and/or magnesium. The idea behind is that vitamin D3 helps to assimilate calcium and that it depletes magnesium. I do not recommend such products. As already explained, taking vitamin D3 without vitamin K2 and vitamin A can lead to the calcium being deposited in the wrong place (your arteries rather than your bones). In addition to that, not everyone needs additional calcium, and not everyone needs additional magnesium, even if they show symptoms of deficiency. Sometimes people have signs of a calcium deficiency but they actually lack magnesium, which the body needs to make use of the calcium it already has and vice versa. Everybody is different and has unique dietary and nutrient needs. Knowing more about your individual metabolism, i.e. your Metabolic Type, can help determine what your individual needs are.

Because nutrients do not exist in isolation, I prefer Real Food and supplements derived from Real Food over isolated nutrients. In the case of vitamin D3, the most natural and most traditional food based supplement is cod liver oil. Cod liver oil is naturally rich in vitamin D3 and vitamin A, which need each other for ideal assimilation and also keep each other in balance, avoiding toxicity. In nature, all foods rich in vitamin D3 are also rich in vitamin A. They also always come with fat, which improves assimilation (both vitamin D3 and vitamin A are fat-soluble), and with cholesterol (it is the cholesterol in our skin that allows us to produce vitamin D3 from sunshine). Pure cod liver oil doesn’t have vitamin K2 though, but remember that one supplement is not meant to provide everything all by itself, but rather to be a complement to a nutrient-dense, whole foods diet that doesn’t exclude whole food groups. Such a diet would contain vitamin K2 in the form of raw dairy (especially hard cheeses and grass-fed butter), egg yolks and poultry liver. Alternatively, one can choose a product combining high-quality cod liver oil with high-vitamin butter oil (see below) or combine two products: a high-quality cod liver oil and another supplement combining vitamin D3 and K2. I personally alternate between the two. Cod Liver Oil has the additional advantage to provide some omega 3 fatty acids, too (not as many as a pure omega 3 fish oil though).

I recommend the following products: