Nutrition Hotline: this issue's Nutrition Hotline considers the differences between whole wheat and gluten-free flours and looks at whether foods supplemented with large amounts of iron can pose health risks.
QUESTION: "How do the gluten-free flours compare nutritionally to whole wheat flours?" J.M., MD
ANSWER: Gluten-free flours can be used by people with celiac disease, a disorder that causes intestinal problems when products that contain gluten are eaten. Gluten is a protein in wheat, rye, and barley. Gluten-free flours are often made from other grains (rice, millet), nuts (almonds, hazelnuts), or dried beans (soy, fava, chickpea).
The level of nutrients in gluten-free flours varies, so you need to read their labels. Many flours, including whole wheat flour, have between 80 and 120 calories per quarter cup. Flours that are higher in calories include potato flour, brown rice flour, almond meal, and hazelnut meal.
In general, gluten-free flours have a similar amount of protein compared to whole wheat flour. Soy flour and lava bean flour are higher in protein than most other flours. Flours based on nuts, such as hazelnut meal and almond meal, are higher in fat than other flours, 17 and 14 grams of fat per quarter cup, respectively.
Gluten-free flours that are highest in fiber are coconut flour and lava bean flour. Rice flour, whether brown rice or white rice, has the least fiber.
Whole wheat flour is a reasonably good source of iron, zinc, and niacin. Most gluten-free flours are also good sources of these nutrients, with soy flour being especially high in iron. Potato flour and white rice flour are low in iron and zinc.
QUESTION: "Have you noticed the large amounts of iron added to many foods? Some breakfast cereals have 75 percent of the RDA of iron in one bowl. That means a 4-year-old would be getting way too much iron, if even he or she eats only one bowl per day?" R.L., via e-mail
ANSWER: If a cereal contains 75 percent of the Daily Value for iron, that would be 13.5 milligrams of iron (75 percent of 18 milligrams). The same committee that developed the Recommended Daily Allowances (RDAs) also developed a number called the Tolerable Upper Intake Level. This number is the highest average daily intake of a nutrient that is likely to pose no risk of adverse health effects. For iron, for a 4-year-old, the Tolerable Upper Intake Level is 40 milligrams, considerably above the amount of iron found in a bowl of cereal.
Of course, if children consume several bowls of highly fortified cereal along with iron supplements, they could get too much iron. Consuming higher amounts of iron, especially as an iron supplement on an empty stomach, may cause stomach upset.
Symptoms of iron toxicity (the kind of poisoning you sometimes hear about when children swallow a bottle of iron pills) occurs with a dose of between 20 and 60 milligrams per kilogram body weight or approximately 9 to 27 milligrams per pound. For a child weighing 35 pounds, this would be between 315 to 945 milligrams. It is unlikely that children would get these amounts from food.
REED MANGELS, PhD, RD
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|Date:||Jan 1, 2009|
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