In a recent study, researchers found that vitamin D levels in the blood are linked to cardiorespiratory fitness.
The research was conducted by a team at Virginia Commonwealth University
They found higher levels of vitamin D are associated with better exercise capacity.
Previous research had shown that vitamin D has positive effects on the heart and bones.
It is well established that vitamin D is important for healthy bones, but there is increasing evidence that it plays a role in other areas of the body including the heart and muscles.
Cardiorespiratory fitness, a reliable surrogate for physical 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.
This study examined whether people with higher levels of vitamin D in the blood have improved cardiorespiratory fitness.
The study was conducted in a 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.
Of 1,995 participants, 45% were women, 49% were white, 13% had hypertension, and 4% had diabetes.
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, with a 2.9-fold strength, after adjusting for factors that could influence the association.
Each 10 nmol/L increase in vitamin D was associated with a statistically significant 0.78 mL/kg/min increase in VO2 max.
This suggests that there is a dose response relationship, with each rise in vitamin D associated with a rise in exercise capacity.
The team noted that this was an observational study and it cannot be concluded that vitamin D improves exercise capacity.
But the association was strong, incremental, and consistent across groups.
This suggests that there is a robust connection and provides further impetus for having adequate vitamin D levels, which is particularly challenging in cold, cloudy places where people are less exposed to the sun.
On the other hand, Vitamin D toxicity can lead to excess calcium in the blood, which can cause nausea, vomiting, and weakness.
Toxicity is caused by megadoses of supplements rather than diet or sun exposure, so caution is needed when taking tablets.
Regarding further research, the researchers suggest studies are required to determine how much the heart needs to function at its best.
Randomised controlled trials should be conducted to examine the impact of differing amounts of vitamin D supplements on cardiorespiratory fitness.
The team suggests it is important to ensure the vitamin D levels in the body are normal to high. people can do this with diet, supplements, and a sensible amount of sun exposure.
The study is published in the European Journal of Preventive Cardiology.
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Source: European Journal of Preventive Cardiology.