Vitamin D remains a hot topic in the world of science and medicine. At this point, most doctors are checking vitamin D levels in patients, finding that many are below the recommended minimum of 20 ng/ml.
Vitamin D is a fat-soluble vitamin that is critical for the absorption of calcium and plays a major role in the regulation of blood levels of calcium and phosphorus. In this way, it's vital to bone strength and growth. Newer research is finding that vitamin D is also a key player in regulating cell growth, inflammation, neuromuscular and immune function, all of which can be directly correlated to many diseases.
Vitamin D is called the "Sunshine Vitamin" because the body uses the sun's ultraviolet B rays absorbed by the skin to make vitamin D. Northern latitudes, winter months, darker skin and the use of sunscreen decrease the amount of sunlight that can be absorbed, creating a risk for low levels of vitamin D. Excess body fat and aging reduce the production of vitamin D, creating a need for obtaining vitamin D from other sources. Keep in mind, dermatologist definitely still want us to use sunscreen! They recommend that we get vitamin D from food and supplements instead of relying on the damaging effects of the sun.
Naturally occurring food sources of vitamin D include fatty fish (salmon, mackerel, tuna, herring and sardines,) cod liver oil, and egg yolks. Many foods are now fortified with vitamin D including milk and cereals and sometimes yogurt and juices.
Food Sources IU
Cod liver oil, 1 Tbsp 1,360
Salmon, 3 oz 447
Mackerel, 3 oz 388
Tuna, 3 oz 154
Milk, fortified, 8 oz. 115-124
Orange juice, fortified, 8 oz 100
Yogurt, fortified, 6 oz. 80
Margarine, fortified, 1 Tbsp. 60
Liver, 3.5 oz. 49
Sardines, 2 46
Egg, 1 41
Cereal, fortified, 1 serving 40
Vitamin D is essential for bone health. When vitamin D levels are too low during growth, children can develop the bone malformation disease Rickets. Chronic low levels in adults can result in osteomalacia, a softening of the bones and muscles, while adequate vitamin D intake reduces the risk for osteoporosis.
Newer research is providing evidence that vitamin D may play an even greater disease fighting role than previously thought. One blind study done in Japan found that children who were given vitamin D supplements had 40% fewer incidences of type A influenza. In laboratory studies, vitamin D has shown an ability to reduce cancer cell growth. Low vitamin D levels may be a risk factor for developing heart disease, diabetes, auto-immune diseases such as multiple sclerosis, depression, SAD (seasonal affectiveness disorder), asthma, cancer, tuberculosis, and other infectious diseases. Even overall mortality--dying for any reason-- seems to be higher in people with low vitamin D. While it's clear that adequate levels are necessary for health, will more vitamin D actually reduce our risk of disease even more?
After reviewing the bodies of current research showing the importance of vitamin D, the recommended intakes were upped in November 30, 2010, by the Institute of Medicine:
Adequate Intake Upper Tolerable Level
Ages 0-6 months 400 IU 1000 IU
6-12 months 400 1500
1-3 years 400 2500
4-8 years 400 3000
9-70 years 600 4000
71+ years 800 4000
Some experts in the medical field question whether the new recommendations were raised high enough to promote good health. While waiting for more research to provide more definitive answers, many doctors and experts are recommending a daily vitamin D supplement of 800-1000 IU. Vitamin D comes in 2 forms: D2 and D3. Most experts recommend choosing D3 for supplements, since it is the form that is actually made in your body and appears to be better utilized. Talk to your doctors about your blood level of vitamin D and ask if supplements are appropriate for you.
Be Healthy With D!