Dr. Judith Reichman TODAY contributor • Profile • E-mail

To take or not to take vitamins, the answer to that question seems to depend on the latest study and who you ask. We are told by many experts to get our vitamins from food rather than mega-doses of supplements. Others tell us that our food is not fresh, we eat the wrong things and to stay healthy we need to take supplements.  

But even with the “right” nutrition, it turns out that many of us are lacking Vitamin D, and this can have some extremely serious health consequences. Dr. Judith Reichman, TODAY medical contributor, how to get a better drade in "D”:

What does “D” do?

This is, quite frankly, an amazing vitamin that may have been undervalued. Most of us (physicians included), thought we just needed “some” to prevent rickets and bone deformities; and that once our food (milk and cereal) was fortified with D we didn’t have to worry, at least when it came to our kids. We have acknowledged that Vitamin D is a bone vitamin; it plays a role in calcium absorption and bone metabolism. Indeed, without D only 10 to 15% of dietary calcium is absorbed whereas adequate amounts of D can more than double calcium absorption. And we all know we need calcium to fight the development of osteoporosis. In its bone building capacity, Vitamin D also prevents over production of hormone from the parathyroid glands which when too high can “leach” calcium from the bones. But did you know that D’s affect on bones starts in the womb: If a pregnant woman is D deficient, her developing fetus may suffer from growth retardation and (especially if the baby breastfeeds and doesn’t get additional D) then become high risk for fractures and later age osteoporosis.

D is much more than a bone vitamin. It is crucial to many of our tissues and organs; these include the brain, prostate, breast, colon, heart, lung and muscle as well as our immune cells.  Vitamin D controls more than 200 genes that go on to direct cellular processes such as division, growth, development, blood supply and degeneration. It can make normal cells grow and abnormal ones (cancer cells) die. It also helps immune cells destroy certain infectious agents, such as TB.

How do we get our D?

Three ways: Exposure to sunlight, through food and taking supplements:

Sun: Ultraviolet B waves penetrate skin and convert a type of cholesterol in the skin to D (D3).

Diet: D is present or fortified in some (relatively few) foods. It’s contained in oily fish (salmon, mackerel, sardines), and fortified milk (one glass has 400 units). There is very little in breast milk.

Supplements: Over the counter vitamin D comes in the form of D2 or D3. Prescription Vitamin D is D2 (D2 is 30% as active as D3).

Vitamin D from all these sources is metabolized in the liver to 25-hydroxy Vitamin D. This is the form of D that is measured in blood tests, but to be active, enter the cells and attach to receptors this D has to be further metabolized by the kidneys and other tissues to 1, 25-dihydroxy Vitamin D (in case you must know the official name).

Know your D levels

• You are considered Vitamin D deficient if your blood level is less than 20 nanograms per milliliter (ng/ml).
• You are low or have relative insufficiency of Vitamin D between 21 and 29 ng/ml.
• You have sufficient D if the level is 30 or greater.

Based on these levels, estimates are that one billion people worldwide have Vitamin D deficiency or insufficiency.

Why are so many of us D deficient?

Let’s start with newborns. Breastfeeding is, without doubt, the healthiest way to feed a baby. Pediatricians currently recommend that breast milk be used as the sole nutrition for the first six months of life and then continued to one year of age. But unfortunately, breast milk contains very little Vitamin D, especially if mom is not “super-sizing” her intake or sun absorption of D. Even if mom takes a multi-vitamin with 400 international units (IU) of D or drinks milk (2-3 glasses a day), studies have shown that the majority of infants are still not getting enough D. Hence, it’s recommended that breast fed infants be given supplements of at least 400 units of D a day, although many pediatricians feel 1000 to 2000 units are appropriate.

Toddlers and children often don’t get their “sunlight D” because they are told to play outside when peak sun hours have passed. If they are out between 10AM and 3PM, they are covered up with clothes and sunscreen which prevents UVB rays from penetrating their skin. This cautionary behavior obviously prevents sunburns that, at an early age, are known to cause malignant melanoma.

And then added to the “low D issue” is the fact that so many children are spending countless hours indoors watching TV and computer screens when not in school. Children who live in the inner city are not getting much sunlight at any time of day and are especially vulnerable to lack of D. And finally, children with dark skin have less absorption of UVB radiation when their skin is exposed.

Adults: Winter and the diminution of UVB rays from the sun causes D deprivation in both children and adults, especially if they live at latitudes that are greater than 35 degrees from the equator.

The elderly: Age is a D detriment, since in the “growing older” population the kidneys are less capable of converting Vitamin D to its biologically active form.

Studies have shown that up to 50% of girls and adolescent females are D deficient, especially if they are black or Hispanic. Individuals of any ethnic group tested at the end of winter are more likely to have low D levels. One study found that 32% of healthy students, physicians and residents working at a Boston hospital (who drank milk and took a daily multi-vitamin) had low levels of D. The higher the latitude, i.e. the further from the equator, the more likely a population will be sun deprived and low in D.  However, even in “sunny- near-the–equator” countries, where clothes are worn to shield most of the skin for religious, political or health concerns (examples: Saudi Arabia, Australia, Turkey, and India) Vitamin D deficiency is common. Indeed it’s been found to occur in 20 to 50% of the children and adults.

Pregnant and lactating women are also at considerable risk for low D, even if they take “regular” prenatal vitamins, eat fish or drink milk. One study found 73% of the women and 80% of their infants were deficient in Vitamin D at the time of birth.

Obese individuals store Vitamin D in their fat cells where it becomes less available to other tissues and hence may result in a relative lack of available D.

MORE FROM HEALTH

Health Section Front

David Duchovny not alone in sex addiction Kids bored with breakfast? Get creative Vitamins, family style: What to take when Wise answers to old wives' tales Experts: ‘Cheating gene’ not a predictor Closet-eater shapes up, sheds 100lbs Leading geneticist to pen book on disease Battle of the bulge: How to blast back fat It’s back-to-school time for bedbugs Now hear this: Don't remove earwax Health Section Front   Add Health headlines to your news reader: