Vitamin D is the newest media darling capturing headlines and causing confusion. With the news covering studies that claim up to 40% of Americans are deficient in this key nutrient, you are likely wondering, am I getting enough D? If not, where the heck do I get it? Allow us to “D” mystify you. Let’s start with “D” basics.
Just “D” Facts, Ma’am
Vitamin D is, in fact, more accurately labeled a hormone. The chemical is actually created by your body in a complex dance involving your skin, liver and kidneys. Step one takes place when a form of cholesterol found in your skin interacts with ultraviolet light from the sun converting the light to cholecalciferol, a precursor form of D3 . The D3 then travels through your bloodstream to your liver, where your body converts it into hydroxyvitamin D and sends it on to your kidneys.Your kidneys then transform it into a form of the nutrient that your body can readily use. So that answers the question of what exactly Vitamin D is.
Now let’s tackle why the hormone/vitamin is so important to your health. First, your body must have Vitamin D to absorb calcium for body bone growth and repair. D deficiency has also been linked to an increased likelihood of breast, prostate and colon cancer. It is identified as a factor in depression, heart disease and weight gain. There is even early evidence linking a lack of this vitamin to autism, autoimmune disease, diabetes and osteoporosis.
So Why Are We So D’ – ficient?
Decades ago, most of us worked out in the sunshine, and absorbed approximately 10.000 – 20,000 IU of vitamin D with only 15 minutes of sun exposure. Today Americans work and play indoors almost exclusively and, if you live in the Northern latitudes, gray skies September through April can also contribute to lack of exposure to the sun’s rays. Additionally, those with darker skin tones which contain more melanin have an added challenge getting enough D, as melanin acts as a natural sunscreen.
Other factors that may contribute:
- Osteoporosis – Improper absorption of calcium is common among people age 65 to 70 years often leading to bone loss, and osteoporosis. Recent data suggests that inadequate metabolism of Vitamin D contributes significantly to decreased calcium absorption in osteoporosis patients as well as older adults without the disease.
- Improper liver or kidney function – both organs are critical for the conversion of sunlight into Vitamin D
- Obesity – Excess fat in the body may actually inhibit the bioavailability of Vitamin D.
- Gut Issues – Those receiving Vitamin D via fortified foods or supplementation rely on the digestive system to properly absorb the nutrient. People with intestinal disorders that limit absorption of fat such as Crohn’s or celiac disease are particularly at risk of deficiency.
- Aging – Aging reduces the concentration of the substance in the skin that is critical for the conversion of sunlight to Vitamin D.
“D”-elivering the Goods
So how much do you need and how do you get it? The Institute of Medicine recommends 600 IU/per day for people 9-70 years of age and 800 IU/per day for those 71 and older. Some studies have found that 5-30 minutes of sun exposure on your unprotected face, arms, legs or back between the hours of 10 a.m. and 3 p.m. 2-3 times weekly is enough for your body to produce all the D3 it needs. You can get Vitamin D from a few food sources such as egg yolks, cod, sardines, and shrimp or by consuming fortified foods like dairy products and nut milks. Obviously, supplementation is also an option. The addition of calcium to your daily supplement routine is also suggested. There is strong evidence that vitamin D and calcium nutrition can be improved in older adults with a Vitamin D intake of 800 IU together with 1000 mg of calcium daily. This combination is a simple, inexpensive strategy that can reduce the likelihood of fractures during a fall.