Just a quick one today, addressing a recent study into the effects of vitamin D supplementation!

It’s been touted as a super vitamin that can improve your physical performance, and barely anyone gets enough of it in their diet – so should you be supplementing yourself with vitamin D? The benefits are numerous, including skin health as well, as noted on this article at sdaraskin.com.

You may/may not have heard that a deficiency of vitamin D in the diet could impair skeletal muscle function, and have negative effects on physical performance. What you may not know is that a vitamin D deficiency is commonplace in both the general population and also among athletes. A recent study at the John Moores University in Liverpool has therefore striven to uncover what effects, or lack of effects, supplementation of vitamin D has on the markers of physical performance.

The Study

Method

30 athletes were selected to have their 1RM (one rep maximum) in the bench press, leg press, and jump height taken – and were then distributed randomly among 3 groups;

• placebo (no supplementation)
• taking 20 000 IU/week oral vitamin D(3)
• taking 40 000 IU/week oral vitamin D(3)

The athletes participated in the study for 12 weeks, with both active supplementation groups taking their doses weekly for the duration of the study.

The 1RM of each athlete was then taken again 6 and 12 weeks post-supplementation.

Results

Before the study started, the original analysis of the participants showed that of the 30 athletes, 57% of them were vitamin D deficient.

During the course of the study, at both the 6 week and 12 week checkpoints, actively supplemented groups (20,000 IU/week and 40,000 IU/week) unsurprisingly had increased concentrations of vitamin D in all participants – with no member at a deficient level. While the placebo group actually had lower concentrations of vitamin D than before the study, when they were tested during weeks 6 and 12 of the study.

The study also found that, after 12 weeks of supplementation increasing concentrations of vitamin D in athletes – there was no increase in their chosen markers of physical performance (the 1RM bench, leg press, and vertical jump).

What to take from the study

It’s pretty clear from the results, that vitamin D supplementation is fairly useless for increasing physical performance.

We can say for certain that at the doses of 20,000 and 40,000 IU/week used in the study, supplementation for 12 weeks at least, is not worthwhile.
I would like to extrapolate upon that, and say that since those doses allowed all participants in those groups to no longer be (what the US Institute of Medicine defines as) deficient in vitamin D, then even with a higher dose – it’s unlikely supplementation will offer much/any advantage in physical performance.

Bottom line is; as has often been shown with widely-acclaimed ‘performance enhancing’ vitamins, it’s a lot more talk than actual proven science – and as far as supplementation goes – you’re better off saving your money.

If you do want to increase the level of vitamin D in your diet, it’s always preferable to do it naturally. So try eating foods notably high in the substance – sea food, eggs, mushrooms, ham, sausages!

– Dan