Under the grey skies of the UK, a childhood disease thought to have been almost eliminated half a century ago is rising up like a specter from the past, spooking parents and doctors alike. Rickets, a condition which evokes images of a bygone era of childhood malnutrition, is on the rise in a big way, and its principal cause is a lack of vitamin D.

This phenomenon isn’t limited to the British Isles however. Vitamin D deficiency has already become a global pandemic, yet remains frequently overlooked by both media and health professionals. Recent research suggests that more than 80% of the European population and half of the world are vitamin D deficient. It is possible to obtain vitamin D principally from food and food supplements, but the main and best source of vitamin D is sun exposure.

Conflicting recommendations about the risks of sun exposure and its relationship to skin cancer has contributed to a lack of exposure to the sun’s UV rays as people cover up and use sunscreen. Nonetheless there are a multitude of factors at work here, and a sharp rise in time spent indoors must be considered as a significant contributing social factor.

Vitamin D is absolutely essential for human health. Most of the body’s tissues and cells have vitamin D receptors. It helps in regulating the immune system, and is necessary for the transformation of blood calcium to bone calcium — essential for strong bones. Deficiency has been linked to a number of illnesses such as osteoporosis, osteomalacia, diabetes, multiple sclerosis, heart disease, hypertension, depression, obesity, dementia and cancer.

In children, this deficiency is the principal cause of rickets, a condition involving the softening of the bones, which can result in growth retardation, skeletal deformities, fractures, muscle weakness, hypocalcemia, tetany, seizures and in untreated cases can lead to mortality.

Dr. Michael Holick, an endocrinologist and professor of medicine, physiology and biophysics at Boston University, is at the leading edge of current vitamin D research. He explains that after the epidemic scourge of the 19th century, rickets was thought to have been almost eradicated with the introduction of fortified foods, but that it is indeed now becoming a frequent occurrence globally in both breast and bottle fed infants. In most cases when a baby is detected with vitamin D, deficiency the mother is found to suffer from the same condition.

Other specific populations at very high risk of vitamin D deficiency include the elderly, those who are confined indoors, and people who do not receive adequate sun exposure due to wearing traditional forms of dress such as burkas.

Vitamin D occurs naturally in a few foods such as oily fish (salmon, mackerel, tuna, sardines and herring) and oils from fish, including cod liver oil. In smaller amounts, it exists in foods such as egg yolk and raw milk, and in fortified foods such as juices, breads, yogurts, cereals, milk, and cheese. In its pharmaceutical form it can be obtained as ergocalciferol (vitamin 2) and cholecalciferol (vitamin 3).

Experts agree that more research is needed into how much vitamin D supplementation is truly optimal. According to a paper by Hanley, the maximum routine daily recommendation for adults is up to 2000 IU. They advise that anyone regularly taking a dose above this limit should be monitored.

Research also suggests that vitamin D2 is not as beneficial as vitamin D3 since it is not as potent and its absorption by the body is less efficient. Direct sunlight exposure facilitates synthesis of vitamin D by the body itself, and there is evidence that this provides additional benefits which the supplements alone cannot.

In order for the body to synthesize vitamin D, direct sun exposure is needed. The recommended amount of exposure has been found to depend on a whole range of factors such as skin pigmentation, age, altitude, latitude, diet, clothing and an individual’s current vitamin D levels. Consequently, it is impossible to provide accurate general guidelines as to how much sun exposure is required to avoid vitamin D deficiency.

Medical experts advise that exposure to sunlight or ultraviolet light without sunscreen increases the risks of cancer and premature aging. There are no definitive guidelines as to how much direct unprotected sunlight exposure is safe. In recommending vitamin D supplements, doctors ensure that individuals obtain the necessary amounts of vitamin D without exposing themselves to other health risks.

On the other hand, it is proven that sun exposure is not only beneficial but essential for human beings. Still in much of the Western world, this fear of sunlight coupled with the long dark days of winter, and rainy summers without enough sun are keeping us from obtaining even the minimum sunlight necessary for our bodies to obtain the chemical benefits. Our sedentary lifestyles frequently keep us closer to the dim light of a bulb or that of a flickering computer screen than to the sun, and even when we do exercise we often choose to do this indoors in a gym or sports facility. It seems that it is high time we turn once more to worship the sun — source and sustainer of all life on Earth.

References

Gartner, L. (2003). Prevention of Rickets and Vitamin D Deficiency: New Guidelines for Vitamin D Intake PEDIATRICS, 111 (4), 908-910 DOI: 10.1542/peds.111.4.908

Hanley, D., Cranney, A., Jones, G., Whiting, S., Leslie, W., & , . (2010). Vitamin D in adult health and disease: a review and guideline statement from Osteoporosis Canada (summary) Canadian Medical Association Journal, 182 (12), 1315-1319 DOI: 10.1503/cmaj.091062

Heaney RP, Recker RR, Grote J, Horst RL, & Armas LA (2011). Vitamin D(3) is more potent than vitamin D(2) in humans. The Journal of clinical endocrinology and metabolism, 96 (3) PMID: 21177785

Holick MF (2006). Resurrection of vitamin D deficiency and rickets. The Journal of clinical investigation, 116 (8), 2062-72 PMID: 16886050

Holick MF, & Chen TC (2008). Vitamin D deficiency: a worldwide problem with health consequences. The American journal of clinical nutrition, 87 (4) PMID: 18400738

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