Winter is coming, which means it’s time to stock up on our vitamin D. But people who use supplements to get sufficient amounts of this essential nutrient will want to make sure they’re getting the right kind.
In research published last year in the journal Nutrition Reviews, scientists at the University of Surrey in the UK examined the literature on vitamin D supplementation. They found evidence that vitamin D2 supplements can decrease people’s levels of vitamin D3, the kind that our bodies naturally make with the help of sunlight. Though D2 supplements can still be helpful, the researchers argue that people should generally stick to D3 supplements instead if they need to raise their vitamin D intake.
“This study suggests that subject to personal considerations, vitamin D3 supplements may be more beneficial for most individuals over vitamin D2,” said lead author Emily Brown, a PhD research fellow at the University of Surrey’s Nutrition, Exercise, Chronobiology & Sleep Discipline program, in a university statement shared via ScienceDaily.
D2 vs D3
Among other things, vitamin D is important for maintaining our bone health and immunity, and it helps our bodies more efficiently absorb other nutrients like calcium and phosphorus. We can get vitamin D from certain foods or by making it ourselves when our skin is exposed to ultraviolet radiation, a.k.a. sunlight. The latter is harder to do during the darker months of the year, however, so many people turn to supplements to bridge this gap.
There are two major forms of vitamin D that people can consume via supplements. D2, also called ergocalciferol, is derived from plants or yeast, whereas D3, or cholecalciferol, is the kind our bodies produce. Some research has suggested that D2 might affect the body’s metabolism of D3, but according to the authors, this potential effect hadn’t been quantified. So the team decided to analyze 11 randomized trials that tracked people’s blood levels of D3 after starting D2 supplementation.
Overall, they found a consistent pattern: people who took vitamin D2 supplements showed noticeable reductions in D3 blood levels compared to controls not taking D2 supplements.
What to do about your supplements
Not all the news is gloomy. D2 supplements still increase people’s blood levels of D2, and thus, these products can still raise overall levels of vitamin D, the researchers note.
That said, other research has shown that D3 supplementation is more effective at increasing total vitamin D levels than D2. And there’s even some preliminary evidence that D3 is better at stimulating the parts of our immune system that help provide the first line of defense against viruses and bacteria, according to the authors. Historically, some people have also chosen D2 supplements to lower their consumption of animal-based products, but there are now D3 supplements that are made without animals, the researchers note.
At the end of the day, it won’t kill you to use D2 supplements if you’re worried about not having enough vitamin D. But if you’re looking to get the most bang for your buck, it’s probably best to stick to D3.
