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Frequently Asked Questions

 


I have recently heard that Vitamin A may be linked to osteoporosis. I see Vitamin A in nearly everything on food labels, even my soymilk. What is the connection and how much should I be consuming?

This recent research ("Vitamin A intake and hip fractures among post-menopausal women", J Am Med Assoc 287(1):102-4, 2002, authors - Feskanich, D et al.) may not have made the headlines in your newspaper or nightly TV news. However, this information is very important for everyone concerned about preventing or reversing osteoporosis, particularly women who have been pushed into early menopause due to cancer treatments and thus are at increased risk of an early onset of osteoporosis.

Read the new information regarding this same concern for men at the end of this article.

This study examined the relationship between intake of Vitamin A (from foods and vitamin supplements) and hip fractures in 72,000 postmenopausal women as part of the Nurses' Health Study in the US. Higher levels of Vitamin A intake nearly doubled the risk of hip fractures in those women whose intakes were 10,000 IU vs. those who consumed less than 4,125 IU. This was particularly noticeable in those women not using HRT.

The increased risk was only associated with the pre-formed or animal form of vitamin A (called retinol/retinoic acid or Vitamin A palmitate on food labels). Intake of the form of vitamin A that comes from plant sources, carotenoids such as beta-carotene, did not increase the fracture risk.

Vitamin A is found in some animal foods naturally like fatty fish, liver, and egg yolks. However, the animal form of vitamin A is also added to many other foods like low-fat milks (including soymilk), margarine, cereal, and energy bars. It is also in many vitamin and mineral dietary supplements. Cod liver fish oil is an exceptionally high source of Vitamin A. Become an avid label reader and look for vitamin A content.

What is significant and worrisome about this study is that the increased risk of hip fracture came with dietary vitamin A intake levels previously considered non-toxic. This same relationship has also been shown in some previous Swedish research, too.

The percentages of Daily Value (DV) of Vitamin A listed on food and dietary supplement labels are still based on the 1968 RDA of 5000 IU per day. This RDA is approximately twice as high as the most recent Recommended Dietary Intakes (RDI) for vitamin A by the National Academy of Sciences (3000 IU for men and 2330 IU for women). The recently established safe Upper Limit (UL) for the pre-formed or animal form of Vitamin A is 10,000 IU (the same as 3000 mcg) per day for adults.

Thus, it is easy to see that obtaining an intake at or above the UL would be fairly easy to do when consuming a vitamin supplement with 100% DV for Vitamin A and several fortified foods on a daily basis containing the pre-formed or animal form of Vitamin A. This is the level that was associated with the increased risk of hip fracture.

It is important to note that there are no toxicity concerns regarding the plant form of Vitamin A, beta carotene and other carotenoids, thus no DV, RDI, or UL have been established.

My bottom line recommendations at this time:

(1) Continue to strive to eat 5-9 servings of deeply colored fruits and veggies every day (I aim for 9+ servings/day). The plant form of vitamin A (beta-carotene and other carotenoids) is considered safe. Plants are the healthiest way to obtain beta-carotene and other carotenoids, several of which our bodies convert to vitamin A as needed.

(2) Eliminate or reduce your intake of liver (if you haven't already) to eating it only rarely. Eliminate cod liver oil consumption. (Other fish oil supplements contain negligible amounts of vitamin A - verified by personal communication with Carlson Labs.)

(3) If consuming a multi vitamin/mineral supplement, look for a brand that contains no more than 100% of the Daily Value (5000 IU) of vitamin A and preferably split so that at least 20% is beta-carotene or mixed carotenoids. Do not consume more than 100% from all your dietary supplements.

Examine the label of the multi-vitamin and mineral product you may be taking, along with any other dietary supplements. If Vitamin A is listed but the amounts of retinol, beta-carotene, or mixed carotenoids are not specified, call the company to get the information. I did this for the brand I use (a generic brand "multi" that contains ~100 % vitamins and minerals for people 50+ years). It took less than 24 hours for the company to call me back with the specific amount of the contents along with a phone number and contact name at the manufacturer in case I wanted to follow up with additional questions.

(4) If you smoke, do not consume a vitamin supplement that contains only beta carotene as its source of vitamin A. Even more importantly, get help to quit smoking as soon as possible.

(5) Look at the labels on foods you eat on a daily or very frequent basis (like energy bars, cereal, milk) that may have fortified their product with vitamin A. Read that label to determine (like in #3) how much pre-formed vitamin A you may be consuming. Limit foods that contain 50% or more Vitamin A per serving to 1-2 per week instead of daily, particularly if you are also consuming a multi-vitamin containing 100% of the DV for Vitamin A.

The biological mechanisms are still being studied to fully understand the observed connection between higher vitamin A intake and increased risk of hip fractures. This study shows both how complicated nutrition is and also how young the science is.

Certainly, none of us want to unwittingly undermine one aspect of our health while trying to optimize another. I have always treated my osteoporosis very vigorously, not wanting to find myself having beat my cancer only to die from complications of a broken hip. Thus, I am now paying more attention to my sources and amounts of vitamin A, in addition to calcium, vitamin D, magnesium, strength training, and impact exercise!


Web sites for further information:

(1) JAMA article abstract
(2) Vitamin A information
(3) National Osteoporosis Foundation
(4) Osteoporosis information from Dr. Miriam Nelson

February 2003 update:
High levels of serum retinol (animal form of vitamin A) in men have recently also been associated with higher rates of fracture risk than those men with lower levels. ("Serum retinol levels and the risk of fracture", K Michaelsson et al, The New England Journal of Medicine 348:287-294, 2003.)

This is the first study to show that increased fracture risk also exists in men and also the first study to use a biological marker in addition to reported dietary intakes to assess the intake of vitamin A. Confirming previous dietary intake studies, no relationship was found between the serum level of beta-carotene (the plant form of vitamin A) and increased fracture risk.

I recommend that men also review this new information and compare their intake of pre-formed vitamin A from foods and dietary supplements with my bottom line recommendations.


faq posted 05/02, updated 02/03

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Vitamins

Soy Shake I have recently seen a lot of news articles about the relationship between vitamin D and cancer prevention. Should we all run out and get more Vitamin D supplements? posted 2/06
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Soy Shake Can you provide a list of all chemotherapy drugs called alkylating agents that may potentially have interactions with antioxidant supplements during chemotherapy? posted 10/02
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Soy Shake Should I stop drinking green tea during chemotherapy to avoid consuming too many antioxidants? posted 7/05
Soy Shake I have recently heard that Vitamin A may be linked to osteoporosis. I see Vitamin A in nearly everything on food labels, even my soymilk. What is the connection and how much should I be consuming? posted 5/02, updated 2/03

 


These questions and answers are intended to be of a general informative nature. Please consult with the Registered Dietitian in your cancer center or your health care provider for nutritional advice that can be individualized to your specific medical condition.

Contact Information:
Phone/Fax: 734/996-9260

P.O. Box 130221, Ann Arbor, MI  48113

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