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There is a never-ending stream of nutrition questions. So we looked to a few of our expert sources to find answers about whether flaxseeds matter, why red peppers may be better than others, and if frozen yogurt is just plain old dessert.What are flaxseeds? Why have they received such attention from health food advocates? And are they really necessary in our diet?
Fact: Flaxseeds (aka linseeds) are about the size of sesame seeds and come from the flax plant, a blue-flowering member of the Linaceae family that is grown largely in Canada, China, and the United States. "Various parts of the plants have been used for centuries to make fabric and cloth and for other household and industrial purposes -- for example, linseed oil used by painters comes from flax plants," says Marian L. Neuhouser, PhD, RD, nutrition researcher at Fred Hutchinson Cancer Research Center in Seattle.
"The lignans in flaxseeds produce anti-inflammatory prostaglandins that help to reduce the inflammation that may be associated with asthma, arthritis, osteoporosis, and migraine headaches. The nutrient benefits have been shown to reduce risk for diabetes, reduce blood cholesterol levels, control blood sugar and insulin levels, and promote gastro-intestinal health," adds Neuhouser.
The seeds are brimming with nutrients (including protein, iron, phosphorous, calcium, B vitamins, and vitamin E), all packed into a small and quite tasty little seed, says Janet Brill, PhD, RD, author of Cholesterol DOWN (Three Rivers, 2006). Specifically, flaxseeds are a good food source of fiber, manganese, magnesium, and antioxidants. They may be consumed in the form of ground flaxseed meal or as flaxseed oil. Flaxseed meal contains more fiber and phytochemicals than flaxseed oil, but the oil is higher in omega-3 fatty acids than the meal.
They have a hard outer coating and need to be ground into meal to allow their nutrients to become more bio-available to the body. This may be accomplished easily using a simple household coffee grinder. Whole flaxseeds pass through the gastrointestinal tract intact and have a laxative effect on the body, says Anne VanBeber, PhD, RD, LD, associate professor and chair of the department of nutritional sciences at Texas Christian University.
Fiction: That the omega-3 fats in flaxseeds have the same health benefits as the omega-3 fats in fish, says Jodi (Citrin) Greebel, a registered dietitian in New York City and the president of Citrition, LLC.
Concerns: The primary health benefit is purported to be the relatively high content of alpha-linoleic acid (ALA) -- a type of omega-3 fatty acid. "Consumers need to be a little cautious, though, because the body is relatively slow and inefficient at converting ALA, which has 18 carbons, to the longer chain EPA and DHA, which have the real health benefits of increasing immune function, lowering inflammation, and providing heart and circulatory benefits," says Neuhouser. "Flaxseeds should not be used as the sole dietary source of omega-3 fatty acids. Cold-water fish, such as salmon, contain higher levels of EPA and DHA," adds VanBeber.
Additionally, according to Neuhouser we need to be wary of overconsumption, because flaxseeds can have a laxative effect, resulting in diarrhea.
Bottom Line: Including flaxseeds in the diet is a good way to work toward achieving the desired 1:2 ratio of omega-3 fatty acids to omega-6 fatty acids in the body. The average American diet results in a ratio of between 1:2 and 1:5. A lower omega-3:omega-6 ratio is associated with reduced risk of chronic disease, explains VanBeber.
Fact: Different colored peppers are the result of when the pepper is harvested. "Red bell peppers are fully ripened green bell peppers. Green bell peppers are unripe and immature. Other colors of peppers, such as orange, yellow, and purple, are different cultivars of the bell pepper and reach their appropriate color upon ripeness," says VanBeber, adding that the peppers become sweeter as they ripen. Also, as an interesting side note, all bell peppers contain a recessive gene that inhibits the concentration of capsaicin, which is found in chili peppers. As a result, they are not spicy.
Most research regarding the nutritional value of sweet bell peppers has been conducted using red and green bell peppers. Red bell peppers are one of the best sources of beta-carotene, the form of vitamin A found in plants. And red bell peppers also contain approximately 11 times the beta-carotene of green bell peppers. In addition, they are an excellent source of the phytochemicals lutein and zeaxanthin, which are known to protect against macular degeneration. Bell peppers of all colors are also a good source of B6, fiber, folate, potassium, and many other vitamins and minerals. And they contain the phytochemical lycopene, which has been shown to reduce the risk for certain cancers. One cup of raw chopped sweet bell pepper contains approximately 25 calories.
While red bell peppers have three to four times the vitamin C content of citrus fruits, green, yellow, and orange bell peppers are also higher in vitamin C than citrus fruits.
Also, "A 2007 study published in the Journal of Food Science compared the antioxidant activity in all four colors and found that the content of antioxidant phenolic compounds was greatest in red bell peppers, followed by orange, yellow, and green," says VanBeber.
Fiction: That bell peppers of a particular color are more nutritious than those of other colors.
Concerns: Placing the emphasis on one specific vegetable (or one color vegetable) makes it seem as if other vegetables are not nutritious. All fruits and vegetables are packed with vitamins, minerals, fiber, and phytochemicals (health-promoting properties of plants such as antioxidants). Always eating the same fruit or vegetable causes you to miss out on all the nutrients in other fruits and vegetables. Each color group provides different vitamins, minerals, and antioxidants, so it's important to choose fruits and vegetables from all the color groups: red, orange/yellow, green, blue/purple, and white, says Greebel.
Research indicates that bell peppers of all colors are among the top 10 vegetables for containing pesticide residue when grown conventionally. "It is recommended that when buying bell peppers, individuals look for organically grown varieties," says VanBeber.
Bottom Line: All colors of sweet bell peppers provide good nutrition in the form of vitamins A, C, and B6. They are also good nutritional sources of fiber, folate, molybdenum, and magnesium, says VanBeber. However, red bell peppers pack more vitamin A (beta-carotene) than do the other colors, and they are also sweeter.
Fact: "Frozen yogurt is a sweet treat that can provide some bone-strengthening calcium. However, it contains only about half as much calcium as regular yogurt. Some frozen yogurts are made with a starter culture (Lactobacillus bulgaricus and Streptococcus thermophilus) that aids digestion and has other health benefits, but if these frozen yogurts have been heat treated, the cultures are destroyed. Look for the 'Live and Active Cultures' seal on the label to obtain a frozen dessert with these cultures. Some frozen yogurts can have added probiotics, but the amounts may not be adequate to confer a benefit," says Joan Salge Blake, MS, RD, LDN, registered dietitian and nutrition professor at Boston University and author of Nutrition & You (Benjamin Cummings, 2007).
Fiction: That all frozen yogurts contain live and active cultures.
Concern: Many individuals overindulge in frozen yogurt thinking that it is low in calories, a good a source of calcium (compared with regular yogurt), and has live and active cultures, says Salge Blake. Also, according to the National Yogurt Association, be on the lookout for the following other types of yogurt that might not contain live and active cultures: yogurt-covered pretzels, yogurt-covered candy, and some yogurt-containing spreads and salad dressings.
Bottom Line: "If you choose a frozen yogurt because of its added probiotics, be sure to call the manufacturer to ascertain the type and amount in the product," says Salge Blake. Or look for the National Yogurt Association's Live and Active Culture seal.
Charles Stuart Platkin is a nutrition and public health advocate, founder and editor of DietDetective.com, the health and fitness network and author of The Diet Detective's Calorie Bargain Bible. Copyright 2008 by Charles Stuart Platkin. All rights reserved.
Reprinted with permission from www.dietdetective.com, June 2008.