Are Older Folk at Risk of Vitamin D Deficiency?

Irene Berman-Levine, PhD, RD
March 12, 2003

Dr Irene recently attended an important seminar on vitamin D deficiency given by Dr Michael Holick, of the Vitamin D Laboratory, Department of Medicine, Boston University Medical Center, USA. She reported on this in her newsletter, Nutrition Tidbits ¹ , and we felt this topic to be so significant that we reproduce her article here. Robert Griffith, Editor.

If you studied vitamin D in school you may remember seeing pictures of children with bowed legs. They had rickets, a childhood disorder involving softening and weakening of the bones, primarily caused by lack of vitamin D. It may also occur if the diet has no source of calcium or phosphorus, which is rare in the United States. Without Vitamin D, the body cannot absorb calcium to make strong bones. We have always been concerned about vitamin D in children.
Intervention programs since the 1930's, primarily milk fortification, have made acute rickets relatively rare in the United States. It is most likely to occur during periods of rapid growth, in intercity children where exposure to the sun may be limited by smog or neighborhood safety, and in dark-skinned children.

In recent years we have learned that vitamin D deficiency is also serious in adults. Chronic vitamin D deficiency is most frequently associated with a higher risk of bone problems but it is also related to other diseases, including an increased risk of hypertension and dying from colon, prostate, breast, and ovarian cancer. Biological mechanisms were briefly covered in the seminar, including the role of vitamin D in inhibiting cellular growth.

Muscle weakness and bone pain in adults can be a symptom of vitamin D deficiency. Dr. Holick believes that many people are mistakenly diagnosed with fibromyalgia - they really have chronic vitamin D deficiency because it also can cause similar symptoms. If someone is presenting with muscle weakness and bone pain it is important to evaluate risk of vitamin D deficiency, particularly if there is adequate exposure to sunlight.

Just imagine the huge numbers of home-bound individuals or those in long term care who are rarely exposed to the sun. Senior adults are at greater risk for vitamin D deficiency because aging can cause a four-fold decline in the synthesis of vitamin D. Higher risk in seniors also occurs because of low exposure to the sun. Dr. Holick indicated that having seniors sit in the sun for 15-20 minutes a day significantly improve the synthesis of vitamin D. He said that in some countries, such as Great Britain, they are regularly exposing residents in long term care to special ultraviolet lights indoors, to encourage adequate vitamin D status.

Individuals with dark skin are also at higher risk for vitamin D deficiency. African Americans need 5-10 times the dose of either sun or ultraviolet light to make the same amount of vitamin D as light-skinned individuals. Dr. Holick indicated that 20-50% of African Americans are chronically vitamin D deficient.

Vitamin D deficiency is more difficult to diagnose in adults because physical appearance does not change. We also do not want to wait for legs to bow in children before we diagnose it. The only outward symptoms may be the bone and muscle weakness.

Diagnostic methods are available but underutilized. Measurement of blood levels of 25-hydroxy-vitamin D is the best barometer for vitamin D status. (I would be interested if any readers had ever had this measured. I do not know if every lab is capable of doing the measurement or what it costs but after listening to Dr. Holick's presentation, I intend to find out*).

The Food and Nutrition Board of the National Academy of Sciences recommends vitamin D intakes of 600 IU/day for elders (see table below). This assumes exposure to sunlight, which is not occurring in many elders. Dr. Holick estimates that 1,000 IU of vitamin D a day is required to satisfy the body's needs and maintain circulating concentrations of 25-hydroxy-vitamin D to at least 20 ng/ml. Since Adequate Intake (AI) is supposed to be the level of intake sufficient to maintain healthy blood levels of an active form of vitamin D, the AI recommendations for vitamin D may be increased in the future.

Adequate Intake (AI) for vitamin D

* 1 mcg vitamin D = 40 International Units (IU)

Ages 19-50	5 mcg* or 200 IU
Ages 51-69	10 mcg or 400 IU
Ages 70 and over	15 mcg or 600 IU

Fortified foods are the major dietary sources of vitamin D. Milk in the United States is fortified with 10 micrograms (400 IU) of vitamin D per quart. Although milk is fortified with vitamin D, dairy products made from milk such as cheese, yogurt, and ice cream are generally not fortified with vitamin D. Only a few foods naturally contain significant amounts of vitamin D, including fatty fish and fish oils.

Why not have everyone take vitamin D supplements? Too much vitamin D is also a health hazard. This can only occur with supplements or someone taking too much cod liver oil. The Food and Nutrition Board considers an intake of 25 mcg (1,000 IU) for infants up to 12 months of age and 50 mcg (2,000 IU) for children, adults, pregnant, and lactating women to be the tolerable upper intake level (UL). More can cause vitamin D toxicity. Toxicity symptoms include nausea, vomiting, poor appetite, constipation, weakness, high blood levels of calcium, mental status changes and heart rhythm abnormalities. Vitamin D toxicity can also cause calcium and phosphorus deposits in soft tissues like the kidney.

In summary, many individuals, especially seniors or home-bound who are not exposed to sunlight, are at much higher risk for vitamin D deficiency than previously thought. Vague symptoms such as muscle weakness and fatigue have many causes, but may be related to low vitamin D levels. Measurement of 25-hydroxy-vitamin D to see if it is at least 20 ng/ml is one of the best ways to determine if vitamin D levels are low. If vitamin D levels are abnormally low, supplementation and /or regular exposure to UV light will usually return levels to normal, except for individuals with non-functioning kidneys. Those individuals will need supplementation using a special formula containing the active forms of vitamin D because their kidneys cannot create the type of vitamin D the body needs.

Source

• MF Holick, MD, PhD. Seminar held at the Dietary Supplement Use in the Elderly Conference held at the National Institutes of Health, January 14-15, 2003.

Footnotes
1. You can check Dr Irene's Nutrition Tidbits Newsletter to see what she has found out. For a free subscription, go to: http://www.healthandage.org/Home/gm=22

Related Links
Vitamin D Fact Sheet
Finding the Nutrients Older Adults Need

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