Not just bone health, higher Vitamin D level in blood linked to cardiorespiratory fitness
Vitamin D levels in blood are linked to cardiorespiratory fitness, according to a study published in the European Journal of Preventive Cardiology, a publication of the European Society of Cardiology (ESC).
“Our study shows that higher levels of vitamin D are associated with better exercise capacity,” said Dr Amr Marawan, assistant professor of internal medicine, Virginia Commonwealth University, Virginia, US.
Cardiorespiratory fitness is the ability of the heart and lungs to supply oxygen to the muscles during exercise. It is best measured as the maximal oxygen consumption during exercise, referred to as VO2 max. People with higher cardiorespiratory fitness are healthier and live longer.
“The relationship between higher vitamin D levels and better exercise capacity holds in men and women, across the young and middle age groups, across ethnicities, regardless of body mass index or smoking status, and whether or not participants have hypertension or diabetes.”
This study investigated whether people with higher levels of vitamin D in the blood have improved cardiorespiratory fitness. The study was conducted with 1995 volunteers, a representative sample of the US population aged 20-49 years using the National Health and Nutrition Survey (NHANES) in 2001-2004. Data was collected on serum vitamin D and VO2 max. Participants were divided into quartiles of vitamin D levels.
Participants in the top quartile of vitamin D had a 4.3-fold higher cardiorespiratory fitness than those in the bottom quartile. The link remained significant even after adjusting for factors that could influence the association such as age, sex, race, body mass index, smoking, hypertension, and diabetes.
Dr Marawan said: “The relationship between higher vitamin D levels and better exercise capacity holds in men and women, across the young and middle age groups, across ethnicities, regardless of body mass index or smoking status, and whether or not participants have hypertension or diabetes.”
Each 10 nmol/L increase in vitamin D was associated with a statistically significant 0.78 mL/kg/min increase in VO2 max.
According to an article published in 2014 in the journal Nutrients, “Vitamin D deficiency prevails in epidemic proportions all over the Indian subcontinent, with a prevalence of 70%–100% in the general population. In India, widely consumed food items such as dairy products are rarely fortified with vitamin D. Indian socio-religious and cultural practices do not facilitate adequate sun exposure, thereby negating potential benefits of plentiful sunshine.”
Researchers noted that this was an observational study and further studies are needed to examine the impact of differing amounts of vitamin D supplements on cardiorespiratory fitness. FDA recommends a daily requirement of 400 IU of vitamin D for everyone above 4 years of age.
This research does not prove that vitamin D enhances athletic capacity or performance, though it may do so. Blood levels of vitamin D are surrogate measurements for sun exposure, which causes the skin to produce vitamin D. Research from as far back as the 1930s, 40s and 50s has shown that sunlight exposure, sunbed exposure and sunlamp exposure was able to increase sprint speed, athletic endurance and strength, and decrease reaction time.
Everyone chalked this up to vitamin D production, but sun exposure also produces photoproducts such as nitric oxide, serotonin, endorphins and BDNF. All of these are vital to human health and may also enhance athletic capacity and performance. The one thing we know for sure is that sun exposure does help athletics. We don’t know if vitamin D is the reason.
For information and references: sunlightinstitute.org. Or, read Dr. Marc Sorenson’s new book, Embrace the Sun, available at Amazon.