Vitamin D helps our bodies regulate levels of calcium and phosphate – nutrients that keep bones, teeth, and muscles healthy. Often, sunlight on our skin can be enough to enable us to produce all the vitamin D we need. But when sunshine is lacking, vitamin D must be ingested, and it can be difficult to meet the recommended levels from food alone. This matters because the health benefits of adequate vitamin D intake may be even greater than previously thought.
Vitamin D deficiencies are widespread, with around one billion people, from all age groups and ethnicities, suffering from them, even in countries with year-round sunshine. Indeed, they are particularly common in the Middle East, owing partly to the prevalence of skin-covering clothes and a cultural habit of staying out of the sun. That same habit, together with darker skin, contributes to lower levels of vitamin D among Africans.
Even in industrialized countries, doctors are seeing the resurgence of rickets, a bone-weakening disease that had been largely eradicated through vitamin-fortified milk and other products. And rickets is far from the only disease to which vitamin D deficiency may contribute. Research conducted over the last decade suggests that vitamin D plays a much broader disease-fighting role than once thought.
Dozens more studies point to a potential link between low levels of vitamin D and increased cancer risk, particularly the risk of colorectal cancer (though, based on current evidence, it remains unclear whether vitamin D supplements actually lower cancer risk. Likewise, vitamin D levels may go some way toward predicting cancer survival (though the evidence remains limited here, as well).
We are still a few years away from clinical trials that explore the possible link between vitamin D supplements, higher vitamin D levels, and reduced risk of disease. However, given the public-health implications of such a connection – low vitamin D levels have been linked to a doubled risk of premature death – the research could not be more important. In public health, there aren’t many game changers. Vitamin D may yet prove to be one.