- With Mayo Clinic nutritionists
Jennifer Nelson, M.S., R.D. and Katherine Zeratsky, R.D.
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Jennifer Nelson, M.S., R.D. and Katherine Zeratsky, R.D.
Katherine Zeratsky and Jennifer Nelson
Jennifer K. Nelson, M.S., R.D., L.D., C.N.S.D.
Jennifer Nelson is your link to a better diet. As specialty editor of the Food & Nutrition Center, she plays a vital role in bringing you healthy recipes and meal planning."Nutrition is one way people have direct control over the quality of their lives," she says. "I hope to translate the science of nutrition into ways that people can select and prepare great-tasting foods that help maintain health and treat disease."
A St. Paul, Minn., native, she is certified by the National Board of Nutrition Support Certification, has been with Mayo Clinic since 1978, and is director of clinical dietetics and an associate professor of nutrition at Mayo Clinic College of Medicine.
She leads clinical nutrition efforts for a staff of more than 50 clinical dietitians and nine dietetic technicians and oversees staffing, strategic and financial planning, and quality improvement. Nelson was co-editor of the James Beard Foundation Award-winning "The New Mayo Clinic Cookbook." She has been a contributing author to and reviewer of many Mayo Clinic books, including "Mayo Clinic Healthy Weight for EveryBody," "The Mayo Clinic Family Health Book" and "The Mayo Clinic/Williams Sonoma Cookbook." She contributes to the strategic direction of the Food & Nutrition Center, which includes creating recipes and menus, reviewing nutrition content of various articles, and answering nutrition questions posed to Ask a Specialist.
Katherine Zeratsky, R.D., L.D.
As a specialty editor for the Food & Nutrition Center, Katherine Zeratsky helps you sort through the facts and figures, the fads and the hype to learn more about nutrition and diet.A Marinette, Wis., native, she is certified in dietetics by the state of Minnesota and the American Dietetic Association. She has been with Mayo Clinic since 1999.
She is active in nutrition-related curriculum and course development in pediatrics at Mayo Clinic Rochester and nutrition education related to the physiology and recommended intakes for premature infants.
Other areas of interest include breast milk and formula safety, neonatal feeding, and nutrition for breast-feeding mothers.
She graduated from the University of Wisconsin-Madison, served a dietetic internship at the University of Iowa Hospitals and Clinics, and worked as a registered dietitian and health risk counselor at ThedaCare of Appleton, Wis., before joining the Mayo Clinic staff.
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Nutrition-wise blog
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Jan. 23, 2009
Antioxidant supplements: Prevention in a pill?
By Jennifer Nelson, M.S., R.D. and Katherine Zeratsky, R.D.
I'm more convinced than ever that we need to give up the knee-jerk reflex that supplements are a nutritionally effective way to prevent disease. Why such a strong statement? The two lead articles in the recent issue of the medical journal "JAMA" show that the antioxidant vitamins C, E and the mineral selenium have no effect on preventing prostate cancer or other cancers in men.
Flash back to last year — and the year before that. In April 2008 a sophisticated analysis was conducted of all the randomized trials of antioxidant supplements involving adults. Together the trials included 232,606 participants. The analysis confirmed the previous year's "JAMA" report that the antioxidant supplements beta carotene, and vitamins A and E seem to increase risk of death.
As far back as 2000, large-scale clinical trials did not support — and even questioned — the use of vitamin E and beta carotene for protection against heart disease. And in the 1990s, clinical studies looking at whether antioxidant supplements protected smokers against lung cancer found that beta carotene and vitamin A actually increased cancer risk.
All of these studies have their roots in the observation that people who eat a diet high in vegetables and fruit (main sources of antioxidants) have lower incidence of various cancers and diseases associated with damage from what is called oxidative stress. Researches tested compounds in vegetables and fruit they hoped would prevent or slow down damage to cells caused by oxidation. While this is a laudable goal, it's beginning to be clear that the benefits of an antioxidant-rich diet can't be boiled down and put into a nutritional pill.
Vegetables and fruit are filled with antioxidants in a variety of forms. For example, there are several hundred types of carotenes (beta carotene is just one of them) and 8 forms of vitamin E. This is a strong argument for vegetables and fruit over pills that contain single forms of nutrients. Furthermore, vegetables and fruit contain combinations of these compounds that dynamically interact. Finally, supplements are not regulated and do not undergo the strict testing that drugs do (but that's a topic for another blog).
So rather than chasing after a silver bullet, maybe we should focus on eating a healthier diet. The U.S. Dietary Guidelines recommend eating each day:
- 3 to 5 servings of fruit
- 4 to 8 servings of vegetables
- For a total 7 to 13 servings
And yet a 2005 survey of almost 350,000 adults in the U.S. found that, on average, Americans eat 1.6 servings of fruit and 3.2 servings of vegetables a day. This is terrible!
So what are your thoughts? Did the studies described above cause you to pause and become "anti" about antioxidant supplements? How many servings of vegetables and fruit do you eat every day? I want to hear from you.
33 comments posted
- Gann PH. Randomized trials of antioxidant supplementation for cancer prevention: First bias, now chance - next cause. JAMA. 2009;301(1):102.
- Gaziano MD, et al. Vitamins E and C in the prevention of prostate and total cancer in men: The Physicians' Health Study II Randomized Controlled Trial. JAMA. 2009;301(1):52.
- Lippman SM, et al. Effect of selenium and vitamin E on risk of prostate cancer and other cancers: The Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA. 2009;301(1):39.
- Bjelakovic G, et al. Antioxidant supplements for preventing gastrointestinal cancers. Cochrane Database of Systematic Reviews. 2008:CD004183.
- Bjelakovic G, et al. Mortality in randomized trials of antioxidant supplements for primary and secondary prevention: Systematic review and meta-analysis. JAMA. 2007;297(8):842.
- Dagenais GR, et al. Beta-carotene, vitamin C and vitamin E and cardiovascular diseases. Current Cardiology Reports. 2000;2:293.
- Fruit and vegetable consumption among adults - United States, 2005. Morbidity and Mortality Weekly. March 16, 2007;56(10):213.
33 comments posted