It's well established that vitamin D is essential for bone health, but there's also growing evidence that it plays a key role in other parts of the body, including the heart and muscles. Vitamin D levels in the blood are also linked to cardiorespiratory fitness, confirms this study presented in the European Journal of Preventive Cardiology, which in practice associates higher levels of vitamin D with better exercise capacity.
Lead author Dr. Amr Marawan, a professor of internal medicine at Virginia Commonwealth University in Virginia, points to previous research that suggested the beneficial effects of vitamin D on the heart and bones. The author therefore reaffirms the need to control vitamin D levels and ensure the necessary intake through diet, prescription supplementation and reasonable exposure to the sun.
The cardiorespiratory form is the specific object of this study. Cardiorespiratory fitness, a reliable surrogate for physical fitness, is the ability of the heart and lungs to deliver oxygen to muscles during exercise. The best measure of this capacity is maximal oxygen uptake during exercise (VO2 max). People with better cardiorespiratory fitness are healthier and live longer.
The study is conducted on a representative sample of the American population aged 20 to 49 - ie 1,995 participants - using data from the famous NHANES cohort (National Health and Nutrition Survey 2001-2004). Data included serum vitamin D levels and VO2 max. Participants were divided into quartiles based on their vitamin D levels. 13% of participants were hypertensive and 4% were diabetic. The analysis reveals that:
- participants in the highest quartile in vitamin D levels have 4.3 times higher cardiorespiratory fitness than those in the lowest quartile;
- this link remains significant, with a strength of 2.9 times, after adjustment with factors that may influence the association (so-called confounding factors) such as age, gender, ethnicity, body mass index ( BMI), smoking, hypertension and diabetes;
- each 10 nmol/L increase in vitamin D is associated with a statistically significant 0.78 mL/kg/min increase in VO2 max, suggesting a dose-response relationship of exercise capacity with vitamin D levels .
Thus, there is a strong relationship between higher vitamin D levels and better exercise capacity , in both men and women, in the young and middle age groups, regardless of ethnicity, BMI and even smoking, history of hypertension and diabetes, conclude the authors.
Admittedly, it should be noted that this is an observational study that does not demonstrate cause and effect, however the association was strong, progressive and consistent across different groups of participants. This suggests that there is indeed a strong link and these data call on clinicians and patients alike to be careful to maintain adequate vitamin D levels.
Adequate levels, because in excess, vitamin D toxicity can lead to excess calcium in the blood, which can cause nausea, vomiting and weakness. So no non-prescription supplementation!
