It’s estimated that around one in 5 adults, and around one in 6 children, may have low vitamin D status – an estimated 10 million people across England. We explore the benefits of this vital nutrient and explain why you may need to supplement
What is vitamin D?
Vitamin D isn’t like other vitamins, which are chemicals we need for good health. Often referred to as the sunshine vitamin it’s the only vitamin that can be generated by our own bodies. In fact, it is probably more appropriately described as a ‘pro-hormone’. The energy provided through the sun’s ultraviolet (UV) light leads to natural cholesterol stored in our skin being able to change in form twice, leading to production of vitamin D3, the most beneficial, and biologically active form for humans – also known as cholecalciferol. From here, vitamin D is transported to the liver, then kidneys, where some more chemical changes take place. This allows the vitamin to become activated and take part in its many useful processes.
The Benefits of vitamin D
Vitamin D and your health
In the 1900s vitamin D was linked to preventing rickets. Recent research has shown that it has a role to play in all aspects of health. Vitamin D deficiencies have been linked with high blood pressure1, obesity2, poor lung function3, multiple sclerosis4, and even schizophrenia5. Taking Vitamin D is also important for pregnant mothers, protecting the unborn baby, and helping deliver babies with a healthier heart.
Vitamin D is needed for the incorporation of calcium into the bones, helping bones grow and strengthen. In an article published in the Current Sports Medicine Report in 2010, two scientists Larson-Meyer and Willis discussed emerging evidence that adequate vitamin D intake reduces risk of stress fracture (as well as total body inflammation, infectious illness, and impaired muscle function).
Muscle function: power and strength
A study of ballet dancers found that supplementation with vitamin D helped to improve muscular strength in vitamin D deficient dancers: they were able to jump higher and had fewer injuries. Other research found vitamin D was positively related to muscle power, force and velocity.
Vitamin D deficiency lowers immunity
Many studies (including one of 19,000 people over a six-year period6) have found that low levels of vitamin D result in a higher reported incidence of upper respiratory infections. This has negative consequences for those under physical stress and with often stressed immune systems, such as endurance athletes, and even those who share locker facilities at the gym!
When to take a supplement
Unlike other important vitamins, like vitamin C, dietary sources of vitamin D, usually found in eggs and oily fish, are simply not widely available in sufficient quantities for our needs. In addition, the sun, in northern latitudes, is only strong enough to stimulate vitamin D production in your skin from May to August. To benefit adequately from the sun’s rays, we ideally need 20 minutes skin exposure daily, without sunscreen, between the hours of 10am and 2pm. Even if a person is regularly outdoors (e.g. runners, walkers) the sun exposure they do get is compromised by the use of SPF creams and pollutants. Researchers have found that even distance runners are often not exposed to enough sunshine as they choose to run early morning or evening. A recent US study found that one third of a large cohort of National Collegiate Athletic Association (NCAA) Division I college athletes at a single institution had abnormally low vitamin D levels.