October 6, 2008
Contact: Sarah Wally, (202) 328-7744

Nutrition Wise
Karen Collins, MS, RD, CDN
American Institute for Cancer Research

Q: Is it true that caffeine-containing drinks have a diuretic effect and result in a loss of fluid?

A: No. Despite the popularity of this long-held belief – even among some health professionals – research does not support it. While it’s true that caffeine in large amounts can temporarily increase urinary fluid loss, studies show that beverages containing moderate amounts of caffeine, like coffee, tea and soft drinks, hydrate our bodies just as well as drinks without caffeine. When it comes to calculating daily fluid intake, caffeinated drinks should be counted along with other liquids.

Q: How accurate are scales that claim to measure body fat percentage?

A: These scales merely estimate body fat by measuring how much resistance your body provides to a tiny electrical current. The scales rely on bioelectric impedance analysis (BIA), which evaluates how current is slowed or stopped as it passes through various materials. More body fat equals more resistance. Based on that resistance and other information you enter (including height, gender and age), the scale uses predetermined formulas to calculate an estimate of your percent body fat. While these scales can produce results close to the “gold standard” method of underwater weighing, studies reveal that the estimates can vary. In general, the scales tend to be better for watching changes in body fat over time, rather than for pinpoint accuracy in identifying body fat or for measuring short-term change in body fat.

Results are affected by anything that changes your fluid balance, including consumption of alcohol or caffeine, medications, hormonal changes, recent exercise, drinking or urination. For best results, test yourself at the same time of day and try to keep all of the above influences consistent. Also be sure to follow directions for cleaning and standing on the electrode spots. When purchasing a body fat scale, choose among models carefully. Since the body fat figures are based on standardized calculations, people who exercise even a few hours a week should get a model with an “athlete” mode that uses an adjusted calculation.

Q: Are beets a nutritionally sound choice?

A: With a low calorie content despite their sweet taste, beets are delicious and nutritious. They are an excellent source of folate, a B vitamin that is essential for producing and repairing DNA and may play a role in cancer protection. In addition, their red hue results from the presence of betacyanins, a type of phytochemical with antioxidant properties that may provide additional heart and cancer protection. Animal studies suggest that beets may also prevent carcinogen formation and increase production of immune cells and enzymes that help fight cancer development. To best preserve the nutrients, eat beets raw (for example, simply peel them and grate into salads). While canned beets are still nutrient-rich, gently home-cooked beets are almost three times higher in folate and twice as high in potassium. Cooking beets at home is easy. To start, leave about one inch of the stem intact to minimize color loss while cooking. Next, roast them in the oven or steam them lightly. Finally, pop the beets out of their skin after cooking and enjoy; you might want to wear rubber gloves at this point to avoid temporarily pink-stained fingers.

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