Vitamin D is known as the sunshine vitamin because, uniquely, our bodies create it from direct sunlight on our skin. It’s why vitamin-D deficiency is common in northern Europeans, with an estimated 70% of us not reaching optimum levels.
Recent research from Germany, that reviewed numerous studies into the impact of vitamin D on athletic performance, showed just how important this vitamin is to triathletes. The team showed that over 30ng of 25-OH-D3 (the circulating form of vitamin-D) in 1ml of blood was sufficient to accelerate muscle regeneration after injury, while levels above 40ng/ml of blood protected against stress fractures. But, said the researchers, maximal physical performance comes from levels above 50ng/ml of blood.
You can have your vitamin D levels tested from £28 (betteryou.com), and we’d advise consuming a good-quality daily vitamin-D supplement from September through to March