Nearly 1 billion people worldwide may have a deficiency or insufficient levels of vitamin D -- that's according to a new clinical review published in the May issue of The Journal of the American Osteopathic Association.
Considered a hormone rather than a vitamin, vitamin D is produced when skin is exposed to sunlight and plays an important role in many of the body's functions, including cell growth modulation, neuromuscular and immune function and inflammation reduction.
Many previous studies have linked a deficiency or insufficient levels of the vitamin to a wide range of conditions including multiple sclerosis, cardiovascular disease, asthma, and autism, with the Endocrine Society currently defining insufficiency as between 21 and 30 ng/ml and deficiency below 20ng/ml.
Dr. Kim Pfotenhauer, one of the study's researchers, also pointed out that chronic diseases such as Type 2 diabetes and those related to malabsorption (including kidney disease, Crohn's and celiac disease) greatly inhibit the body's ability to metabolize vitamin D from food sources.
The study also found that as many as 95 percent of African-American adults may have a vitamin D deficiency or insufficient levels, with vitamin D variations found among races due to the differences in skin pigmentation, with lighter skin synthesizing more vitamin D than darker skin.
"People are spending less time outside and, when they do go out, they're typically wearing sunscreen, which essentially nullifies the body's ability to produce vitamin D," explained Dr Pfotenhauer, "While we want people to protect themselves against skin cancer, there are healthy, moderate levels of unprotected sun exposure that can be very helpful in boosting vitamin D."
The researchers added that just 5-30 minutes in midday sun twice per week is sufficient to top up levels, "You don't need to go sunbathing at the beach to get the benefits," said Dr. Pfotenhauer. "A simple walk with arms and legs exposed is enough for most people."
The team also stressed that it important not to wear sunscreen during these short sessions, with an SPF 15 or above decreasing vitamin D3 production by 99 percent.
For those wanting to top up their levels with diet, milk, breakfast cereals, and portobello mushrooms are also fortified with vitamin D, with Dr. Pfotenhauer also recommending supplements -- as long as they are taken as directed and a physician is consulted beforehand -- as they are an effective and low risk option.