The Autumn equinox is here—a reminder that Summer is over as the sun dips lower in the sky and our shadows grow longer. Fall is also a good time to discuss vitamin D deficiency on the occasion of a timely study associating a lack of the sunshine vitamin with increased mortality risk.
The sunshine vitamin
Vitamin D is a vitamin your body uses like a steroid hormone. You make vitamin D from cholesterol through a process dependent on exposure of the skin to the sun’s ultraviolet rays. People living in northern latitudes above an imaginary line drawn across the country from San Francisco to Philadelphia are at risk for vitamin D deficiency.
Vitamin D’s main function is to maintain a balance between blood concentrations of calcium and phosphorus for optimal bone health. It’s also essential for healthy intestines, immune and cardiovascular systems, the pancreas, muscles, brain, and regulation of cell metabolism.
Symptoms of vitamin D deficiency may include bone pain and fractures, muscle weakness, chronic fatigue, confusion and memory problems. What’s more, a study by researchers from the Mayo Clinic in Rochester, MN, found low vitamin D levels were associated with increased death from any cause.
To get their findings, presented at the annual meeting of the American Society for Bone and Mineral Research, the researchers used data from more than 11,000 individuals enrolled in the Rochester Epidemiology Project from 2005 to 2011. Participants were tracked starting 30 days after an initial vitamin D measurement until leaving the county, dying, or until Dec. 31, 2014.
Deficiency and death
A total of 643 participants had vitamin D levels below 12 ng/mL (nanograms per milliliter of blood), 1,605 had levels from 12 to 19, 8,210 had levels of 20 to 50, and 564 had levels above 50. During a median follow-up of 4.8 years, there were 723 deaths. Compared to those with the highest vitamin D levels, those with the lowest were more than two and a half times likely to die during follow up.
According to the researchers, the link between risk of death from any cause and low vitamin D levels could be due to detrimental effects on bone health and resulting falls and fractures. Lower levels of vitamin D could also inhibit the body’s ability to put calcium in the bones where it belongs, resulting in calcification of blood vessels.
Get your vitamin D
A 2013 study published in the journal PLoS One found that vitamin D levels vary throughout the year among Americans, at their highest in August and lowest in February. As opportunities to bask in direct sunlight go away in Fall and Winter, vitamin D supplementation becomes critical to your overall health.
Very few foods are a good source of vitamin D. Those include fortified dairy products and breakfast cereals, fatty fish, beef liver, and egg yolks. Traditional multivitamins contain about 400 IU (international units) of vitamin D, but many multivitamins now contain 800 to 1,000 IU. It generally is not recommended to take more than 2,000 IU daily in supplement form without your doctor’s advice. Since vitamin D is fat soluble, it’s best to take supplements with a snack or meal containing fat.
Harvard Medical School