QUESTIONS AND ANSWERS

Be sure to check out the other questions posed to Miriam Nelson, PhD and Rebecca Layne, MS, CSCS on our web site at FAQs.

Q: I am very confused about vitamin A and bones. Your comments in the last newsletter really got me reading my multivitamin label. My multivitamin supplement says that 20 percent of the vitamin A is from beta-carotene. Is this okay? Also, if the label says IU (international units), how do I convert that to micrograms?

A: We received numerous questions from readers directly following our March newsletter. First, let me give you a little background. Vitamin A is fat-soluble vitamin that can be stored in the body. It is needed for vision. In fact, vitamin A deficiency is the leading cause of blindness in developing countries. However, vitamin A deficiency is extremely rare in our country.

Vitamin A is also needed for the immune system and is important in cell growth and function. The daily value (DV) for vitamin A is 1,500 mcg (or 5000 IU - see below), which is what many multivitamins contain. However, the DRI (dietary reference intake) for women is 700 mcg/day. Most people get around this level in their diet. The DV is the amount that most people in the population are advised to consume, but adult women need not get this much - the DRI is more than adequate to promote health and prevent deficiency. The upper limit for vitamin A is 3,000 mcg/day. The upper limit is the level of dietary intake over which there is evidence of harm.

In foods such as fruits and vegetables, we convert beta-carotene into vitamin A. We also get pre-formed vitamin A in the form of retinol from some fats, liver, eggs, and milk. Most of the vitamin A that is in vitamin supplements comes from retinol.

If your vitamin gives a percentage of how much of the vitamin A is from beta-carotene, you can assume that the rest if from retinol. Therefore, if the vitamin says 20% is from beta-carotene, then 80% is from retinol. In some cases, 100% is from beta-carotene, with none from retinol. I recommend you opt for single nutrient supplements instead - vitamins B6, B12, C, D, E, folate, and calcium. Right now - to the best of my knowledge - there are no multivitamin supplements out there that do not contain vitamin A; hopefully, the supplement industry will quickly respond to the need for a multivitamin that does not contain vitamin A.

In terms of figuring out how International Units (IU) are related to micrograms (mcg), the conversion is 1 microgram of retinol = 3.33 IU. The DRI for vitamin A is 700 mcg, which is equivalent to approximately 2,331 IU (700 * 3.33). Alternatively, if your vitamin says that it contain 5,000 IU, that would mean that it contains approximately 1,500 mcg (5000 / 3.33).

In the research study that I spoke about in March, levels above 2,250 mcg of vitamin A intake were associated with an increased risk of hip fractures. Since we can convert plenty of beta-carotene into vitamin A in the body and we also get appreciable amounts of retinol in our diets, I recommend that you do not get any vitamin A in the form of retinol in a supplement unless specifically recommended by your doctor.

FROM THE MAILBOX

Here are excerpts from a few of the inspiring letters we've received recently. If you enjoy reading them, check out the collection of reader mail on our web site at Success Stories.

"I thought you might like a bit of a success story. Even though I must qualify it, I still think you might be interested. I had an opportunity to get a free BMD test yesterday. It was the ultrasonic, not the x-ray; but I thought it was worth the time, since time was the only expense.

I have been active all my life, and I probably have better than average genetic background; nevertheless, I think that the fact that I've been doing your SWSY and SWSB exercises since the beginning of September must be part of the reason for my good score. My T-score was +1.3 and I'm 72 years old."

-- Tricia

"Two years ago, at the age of 59, I was diagnosed as being osteopenic. This came as a complete shock to me as I thought I was taking adequate amounts of calcium and exercising on a regular basis. Obviously not. A friend, who was diagnosed with osteopenia a few months before I was, gave me your book, "Strong Women, Strong Bones" which I read religiously. I bought the recommended weights, joined a gym, and increase my calcium intake. I was not able to tolerate Fosamax so I could not rely on medication to help increase my bone density.

A month ago I had another bone density test and I would like to quote the doctor's report: 'Her L2 and L4 bone density has increased a statistically significant 8.1 percent to 1.038 gm/cm2 which is now only 1.35 standard deviations below that of a young adult and thus, 0.29 standard deviations above that of an age- matched woman. Her femoral neck bone density has increased an again statistically significant 8.4 percent to 0.764 gm/cm2, which is 1.80 standard deviations below that of a young adult and thus, 0.36 standard deviations below that of an age-matched woman. Thus, this woman has gotten a good benefit from her calcium and strength training and is now only moderately osteopenic...' Your book has made a huge difference in my life and I want to thank you."

-- Susan

RECIPE OF THE MONTH