Vitamin D supplements are recommended during the darkest months in many countries
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Taking a type of vitamin D supplement seems to reduce the levels of another type that is more easily used by the body, which could affect our immune system.
Our bodies create vitamin D when the ultraviolet rays with sunlight convert a protein called 7-Deshydrocholesterol in the skin into a type of vitamin D called vitamin D3. When sunlight is sparse during fall and winter, countries like the United Kingdom recommend that people take supplements.
Two forms of these supplements are available: vitamin D3, or cholecalciferol – which normally comes from lanolin, a waxy substance on sheep wool – and vitamin D2, or ergocalciferol, which mainly comes from fungi. We thought that whatever the one you took.
But now, Emily Brown at the University of Surrey, in the United Kingdom, and her colleagues have carried out a meta-analysis of 11 random controlled trials previously published on vitamin D supplements, with a total of 655 participants.
They found that taking vitamin D2 supplements can cause a decrease in the concentration of the vitamin D3 body. Why happens, or if vitamin D3 supplements reduce vitamin D2 levels, is not entirely clear.
In addition, in many studies, vitamin D3 levels were lower in people taking vitamin D2 than in control groups taking no supplement in vitamin D. “This is an effect previously unknown,” explains Brown.
A 2022 study suggests that vitamin D2 and D3 have overlapping roles but different in the support of the immune function. Only vitamin D3 seems to stimulate the type I interferon signaling system, for example, which offers a first line of defense against bacteria and viruses.
Brown says that the results suggest that vitamin D3 supplements can be more beneficial for most individuals than vitamin D2, but add personal considerations to take into account, as the wish to avoid animal products.
They also don’t mean that people should just stop taking vitamin D2, she said. “Your total level of vitamin D will always be sufficient if you take vitamin D2 supplements, but you may see that it is less effective and that you could lose these additional functions in terms of immune support.”
Ouliana Ziouzenkova of Ohio State University underlines that studies have shown that in the elderly, the conversion of vitamin D3 in its active form called Calcitriol can be less effective, so that D2 supplementation can be particularly beneficial in this population.
“In the absence of all proof of negative effects, if a vegan person is deficient in vitamin D, opting for a D2 supplement on any supplement remains the prudent choice probably,” explains Bernadette Moore at the University of Liverpool in the United Kingdom.
Plant vitamin D3 has started to become more accessible. For example, a tomato has been published at genes to produce vitamin D3, but tests are underway.
Susan Lanham-New, member of the team, also at the University of Surrey, hopes that research will remind people the importance of vitamin D supplements. “There are many people in the United Kingdom and in other regions of northern latitude which in winter obtains a slight osteomalacia [known as rickets in children]Caused by the lack of vitamin D – which presents itself in lethargy, bone pain, muscles, sensitivity to pain to the fatigue of infections – and does not realize, “she says.
