I keep seeing new products labeled "gluten-free." I understand this is important for people with celiac disease, but should everybody try to eat gluten-free?
Answer : Robert M. Russell, MD, emeritus professor at the Friedman School, replies, “The answer is no. In celiac patients there is an immunologic reaction against a component of gluten that is contained in wheat, rye, barley. So, a gluten-free diet is fairly restrictive and expensive to maintain.
That being said, if you are having a problem with intermittent abdominal bloating and pain, unintentional weight loss or chronic diarrhea, you should consult your doctor, who can now diagnose
celiac disease with a simple blood test. A gluten-free diet will result in a prompt lessening of symptoms in those who have been diagnosed with clinical disease. Although many people with celiac disease are asymptomatic, there is no good evidence that a gluten-free diet will benefit most people in any way.”
Does lettuce contain iron? I’ve always wondered,
because the stems frequently turn reddish-brown when cut. If so, why doesn’t bagged lettuce quickly turn brown?
Answer : Lettuce does contain a small amount of iron; according to the USDA’s nutrient database, for example, a cup of green leaf lettuce has 0.31 milligrams of iron. But that’s not why lettuce turns brown. Rather, as with most fruits and vegetables, this browning
is the result of oxidation catalyzed by a naturally occurring enzyme called polyphenol oxidase. When exposed to oxygen—as when lettuce is cut—this enzyme assists in the formation of yellow-colored compounds called quinones. These then further react with oxygen to eventually form melanins, the same type of compounds that give humans a tan.
Bagged lettuce prevents this browning by taking advantage of the carbon dioxide that lettuce naturally produces as it “breathes.” Transparent bags of ready-to-eat lettuce are specially designed to partly keep oxygen out while letting extra carbon dioxide escape. By maintaining the right ratio of oxygen to carbon dioxide, the oxidation that results in browning can be slowed and lettuce kept green.
Is exercise safe for people with chronic obstructive pulmonary disease (COPD)?
Rebecca Seguin, PhD, an adjunct assistant professor at Tufts’ Friedman School and an assistant professor at Cornell University, replies: “COPD is a group of diseases, including emphysema and chronic bronchitis, that cause restricted airflow in the lungs. It also leads to greater strain on the heart, because the amount of oxygen in the blood is reduced. For individuals with COPD, shortness of breath is the most common symptom, and it becomes progressively
more severe over time in many people. While it may seem difficult for someone with COPD to start an exercise program, it is actually essential to maintaining and improving daily function.
"To get started, anyone with COPD should first get approval from his or her doctor. Next, if a formal program—often referred to as pulmonary rehabilitation—is available, that is an excellent choice. There will be exercise physiologists and/or nurses on staff within those programs who have specific training in working with patients with COPD. The other benefit is close monitoring and feedback during supervised exercise sessions. If the program is not an option (or ends), exercise on one’s own is the next best choice. The key is to start any new program slowly, with small but gradual progression in terms of exercise intensity and duration. Walking is a great choice for most people. Activities such as stretching, strength training, and Tai Chi are also recommended. Aim to exercise every other day (three to four days per week), working up to 20-30 minute sessions.
"One important tip for people with COPD to keep in mind is breathing. Because shortness of breath and use of oxygen can be an issue, breathing slowly and gently is very important. Inhale through the nose, and gently exhale through pursed lips. Slowly breathing in this pattern will help give the body the steady flow of oxygen that it needs. While all people benefit tremendously from regular exercise, people with COPD stand to gain additional benefits that can help them manage their COPD over time, such as improving the body’s use of oxygen and having increased energy so that regular activities are easier and shortness of breath is less limiting."
You often write about healthy vs. unhealthy fat. But healthy vegeta-
ble oils simply do not work for baking in most cases. Do you have any recommendations?
Answer : We posed this challenge to Patsy Jamieson, our recipe editor. Here are her thoughts: “Certain recipes like basic muffin batters and quick breads are fine with canola oil, but many flaky pie crusts, cookies and cakes, in which the butter is creamed with sugar, do rely on a solid fat, such as butter, shortening or lard. In the case of pie pastry, the steam created between layers of solid fat and dough during baking is responsible for the flaky texture. Many cake recipes call for creaming butter and sugar until light and fluffy. Air is incorporated during this process, so it is critical to the leavening. I have never found a true substitute for butter in these types of recipes. I have had good results, however, replacing the butter with a 50/50 mixture of butter and canola oil.
“I also lean towards the types of baking recipes that are easily adapted to using oil, rather than butter. For example, the oatmeal crisp recipe in the December issue is based on a classic wafer cookie, which uses melted butter and egg whites. It was easy to substitute canola oil for the melted butter. Cake batters that are lightened with beaten whole eggs (or a mixture of whole eggs and egg whites) are generally good candidates for swapping oil for butter. Light butters are not recommended for baking.”
Is there any difference in the nutritional value of golden flaxseeds
versus brown flaxseeds?
Answer : Both contain four grams of omega-3 fatty acids, primarily alpha-linolenic acid (ALA), in a three-tablespoon serving. ALA, the form of omega-3s found in plants, has been touted for its health benefits. While the jury is still out on ALA’s own possible benefits, be aware that relatively little ALA converts into DHA and EPA, the omega-3s found in fish oil that have been shown to have positive cardiovascular
Flaxseeds are also a good source of dietary fiber. Golden flaxseeds have nine grams in three tablespoons, while brown flaxseeds have only seven grams. The brown variety contains slightly more potassium and calcium, however, while golden flaxseeds have 160 calories per three tablespoons, compared to 140 for brown.
Overall, according to Alice H. Lichtenstein, DSc, director of Tufts’ HNRCA Cardiovascular Nutrition Laboratory, these differences are minor and you could choose either variety if you’re looking to add flaxseeds to your diet.
I’m a 70-year-old male whose usual exercise is weight training with relatively heavy-duty intensity and consistency. I started taking a whey protein supplement to meet my protein needs. Is it better to take with meals or at more times throughout
Roger A. Fielding, PhD, director of Tufts’ HNRCA Nutrition, Exercise, Physiology and Sarcopenia (NEPS) Laboratory, answers, "To enhance the effects of the whey protein it is better to take after exercise and between meals so it does not act as an appetite suppressant and decrease your usual food intake."
Fielding and colleagues have recently studied whether added protein, such as that in whey supplements, could help protect against sarcopenia, the gradual loss of skeletal muscle in the later years of life. Researchers compared the effects of a whey-protein beverage (40 grams/day)against a placebo in a group of men and women ages 70-85 who also underwent resistance strength training. The study concluded that whey-protein supplementation at this dose did not offer additional
benefit in mobility-limited older adults.
Whey protein is a collection of proteins isolated from whey, a byproduct of cheese manufactured from cow’s milk.
V8 juice lists 10 grams for carbohydrates, of which 8 grams are
sugars. Is that too much sugar for a healthful drink?
Answer : That 8 grams of sugar in 8 ounces of V8 juice compares to 28 in the same size serving of a typical non-diet cola, but we can see how that number might still be surprising.
Caitlin Wong, a master’s candidate at the Friedman School and a Frances Stern Dietetic Intern, puts it into perspective: “When talking about a healthful drink, it’s difficult to say how much sugar is ‘too much’ because there are no dietary recommendations for sugar. Sugar is often thought of as a manmade product found only in processed foods. But in fact, sugar is almost universally found in plants, including grains, legumes, fruits and vegetables. Sugars are found in several forms, and are a type of carbohydrate. Regardless of the form or complexity,
however, all sugars are broken down in the body into simple sugars called monosaccharides
(primarily glucose) to be absorbed and metabolized. Whether carbohydrates are coming from an ice cream cone or iceberg lettuce, they all serve one primary function: fuel. While sugar can be used for fuel, excess sugar intake will be stored as fat and can contribute to other health complications. So, does it matter if there is sugar in healthy foods and beverages?
“The important thing to note about V8 Juice is that it is 100% juice with no added sugars. The 8 grams of sugar that are in every serving of V8 occur naturally in the vegetables—tomatoes,
beets, celery, carrots, lettuce, watercress, parsley and spinach. Most probably comes from beets and carrots, ingredients with the highest amount of total sugars per 100 grams—7.02 grams and 3.46 grams, respectively.
“Consumers must also consider the possible benefits of other components in the beverage. An 8-ounce serving of V8 Juice contains only 50 calories, and sugar contributes
more than half of those calories. On the bright side, each serving also contains 2 grams of fiber and 2 grams of protein, and is packed with vitamins A and C. With every food there are pros and cons. Perhaps in this case, the benefits outweigh the costs.
“If there is anything to worry about with V8 Juice, it is probably the sodium content (420 milligrams per serving), which might lead you to pick low-sodium V8 (140 milligrams per serving) instead.”
If I ate as much food every day as listed in your “One Day’s
Potassium Plan” (March), I would gain weight and have to double my blood-sugar medication! Can you suggest
a lower-calorie potassium plan suitable for diabetics?
Answer : Actually, we did compute the calories in our example of how to get 5,419 milligrams of potassium from a day’s worth of meals, but omitted those numbers to avoid reader confusion. You’ll be surprised to learn that this “potassium plan” contains only 1,323 calories. For diabetes patients, the American Diabetes Association recommends getting potassium from food rather than supplements, and suggests “Diabetes Superfoods” that include these from our sample day’s meals: spinach, citrus fruits, sweet potatoes, non-fat yogurt, tomatoes, fish, whole grains and fat-free milk.
Is there any value to drinking cactus juice?
There may be benefits to consuming cactus—
which is, after all, a plant—and people have been eating prickly pear cactus pads and syrup for centuries. But the evidence for the specific
health claims typically made for products containing cactus juice (and other ingredients) is scant. Naturally occurring compounds in cactus called betalains are said to reduce inflammation. The literature on the health benefits of cactus betalains is very limited, cautions Jeffrey B. Blumberg, PhD, director of Tufts’ HNRCA Antioxidant
Nutrition Laboratory. Most studies cited supporting the benefits of products containing cactus juice were conducted in vitro (“test tube” laboratory experiments) or on rats and mice. The primary human study actually focused on curing hangovers; possible anti-inflammatory benefits were inferred as an explanation for the “moderate
effect on reducing hangover symptoms.”
Should Atlantic sardines
be avoided in favor
of Pacific sardines?
If so, why?
Answer : The choice of
comes from concerns about the health of the
oceans, rather than the health of consumers.
The Monterey Bay Aquarium Seafood Watch
advises avoiding Atlantic sardines for now
because “these fish come from sources that
are overfished or fished or farmed in ways that
harm the environment.… Many populations
of Atlantic sardines in the Mediterranean are
declining due to overfishing. This, and ineffective
fishery management, result in an ‘Avoid’
ranking.” Instead, Seafood Watch suggests,
choose Pacific sardines from US waters, rated
a “Best Choice”: “These fish are abundant, well
managed and fished or farmed in environmentally
The Environmental Defense Fund www.edf.org adds that Pacific sardines are low
in contaminants and high in heart-healthy
omega-3 fatty acids: “Adults and children can
safely eat more than four meals per month”
containing these fish.