September 17, 2014

“D” is for Darling

A client calls me in a panic…”Lisa, my lab results are back, and I’m deficient in vitamin D! My doctor says I’m at risk for osteoporosis, rheumatoid arthritis, multiple sclerosis, colon cancer, breast cancer, and heart disease!  Is this true?” “Well,” I say slowly, as to not incite her hysteria any further, “Yes, maybe, possibly, could be, yep, looks that way, respectively.”  My client is not amused. “Okay, explain this to me,” she says imploringly. “What is so special about vitamin D?” What is so special indeed? And why has vitamin D become the darling of doctors everywhere?

Vitamin D is a vitamin, and also a hormone. Its primary duty is to maintain calcium and phosphorous levels in the blood, critical for healthy bones and kidney function. Food sources are slightly limited, and include fortified milk and breakfast cereal, egg yolks, fish oils, and fatty fish. Bonus: we can make enough vitamin D to meet our body’s requirement simply by exposing our faces and arms (sans SPF) to sunlight for a mere 10-15 minutes daily. But the problem is, sunscreen, environmental pollution, frequent cloudy days, and geographical position to the equator, all hinder our ability to produce the vitamin endogenously. So hospitals and doctors across the country started noticing low blood levels of the vital vitamin in those with a variety of chronic conditions, and researchers took note. Was there a connection with certain disease conditions and all those individuals with low labs?

There is no doubt that vitamin D is critical for bone health, and decreased blood levels increase risk significantly for osteoporosis. A study at Hopkins linked low blood levels of vitamin D with rheumatoid arthritis, and a research team at Oxford University found that vitamin D could possibly prevent MS in genetically susceptible individuals. What about cancer? Several studies do support vitamin D and its role in preventing colon cancer, as well as breast cancer.  Increased risk of heart disease has been linked to decreased levels of D, although more research is needed.

As a registered dietitian, I like my patients and clients to get their nutrients naturally. But since food sources are limited, supplementation may be recommended, especially for the elderly, dark-skinned individuals, the obese, smokers, those with liver or kidney disease, and persons living far from the equator (note: above Philly is the solar “cut-off” for us East coasters, so Delawareans generally get the recommended D-dose from the sun). The current recommended daily allowance (RDA) for vitamin D is 200 IU for those aged 50 and under. For individuals between 50 and 70, 400 IU per day is recommended, and for those over age 70, the RDA is 600 IU. Based on research findings, most experts think these recs are too low, and are suggesting between 1,000 and 2,000 IU of vitamin D daily. It is important to note though, that the upper limit of vitamin D is 4,000 IU per day, so don’t overdo it!