Contrary to what their name implies, peanuts are not true nuts but a member of a family of legumes related to peas, lentils, chickpeas and other beans. Peanuts start growing as a ground flower that due to its heavy weight bends towards the ground and eventually burrows underground where the peanut actually matures. The veined brown shell or pod of the peanut contains two or three peanut kernels. Each oval-shaped kernel or seed is comprised of two off-white lobes that are covered by a brownish-red skin.
Health Benefits
In addition to being every kid's (and many grownup kid's) favorite sandwich filling, peanuts pack a serious nutritional punch and offer a variety of health benefits.
Your Heart Will Go Nuts for Peanuts
Peanuts are a very good source of monounsaturated fats, the type of fat that is emphasized in the heart-healthy Mediterranean diet. Studies of diets with a special emphasis on peanuts have shown that this little legume is a big ally for a healthy heart. In one such randomized, double-blind, cross-over study involving 22 subjects, a high monounsaturated diet that emphasized peanuts and peanut butter decreased cardiovascular disease risk by an estimated 21% compared to the average American diet.
In addition to their monounsaturated fat content, peanuts feature an array of other nutrients that, in numerous studies, have been shown to promote heart health. Peanuts are good sources of vitamin E, niacin, folate, protein and manganese. In addition, peanuts provide resveratrol, the phenolic antioxidant also found in red grapes and red wine that is thought to be responsible for the French paradox: the fact that in France, people consume a diet that is not low in fat, but have a lower risk of cardiovascular disease compared to the U.S. With all of the important nutrients provided by nuts like peanuts, it is no wonder that numerous research studies, including the Nurses' Health Study that involved over 86,000 women, have found that frequent nut consumption is related to reduced risk of cardiovascular disease.
Peanuts Rival Fruit as a Source of Antioxidants
Not only do peanuts contain oleic acid, the healthful fat found in olive oil, but new research shows these tasty legumes are also as rich in antioxidants as many fruits.
While unable to boast an antioxidant content that can compare with the fruits highest in antioxidants, such as pomegranate, roasted peanuts do rival the antioxidant content of blackberries and strawberries, and are far richer in antioxidants than apples, carrots or beets. Research conducted by a team of University of Florida scientists, published in the journal Food Chemistry, shows that peanuts contain high concentrations of antioxidant polyphenols, primarily a compound called p-coumaric acid, and that roasting can increase peanuts' p-coumaric acid levels, boosting their overall antioxidant content by as much as 22%.
Peanuts' Antioxidants Key to their Heart-Health Benefits
Research published in the British Journal of Nutrition (Blomhoff R, Carlsen MH), which identified several nuts among plant foods with the highest total antioxidant content, suggests nut's high antioxidant content may be key to their cardio-protective benefits.
Nuts' high antioxidant content helps explain results seen in the Iowa Women's Health Study in which risk of death from cardiovascular and coronary heart diseases showed strong and consistent reductions with increasing nut/peanut butter consumption. Total death rates decreased 11% and 19% for nut/peanut butter intake once per week and 1-4 times per week, respectively.
Even more impressive were the results of a review study of the evidence linking nuts and lower risk of coronary heart disease, also published in the British Journal of Nutrition. (Kelly JH, Sabate J.) In this study, researchers looked at four large prospective epidemiological studies-the Adventist Health Study, Iowa Women's Study, Nurses' Health Study and the Physician's Health Study. When evidence from all four studies was combined, subjects consuming nuts at least 4 times a week showed a 37% reduced risk of coronary heart disease compared to those who never or seldom ate nuts. Each additional serving of nuts per week was associated with an average 8.3% reduced risk of coronary heart disease.
Practical Tip: To lower your risk of cardiovascular and coronary heart disease, enjoy a handful of peanuts or other nuts, or a tablespoon of nut butter, at least 4 times a week.
Potentially Reduced Risk of Stroke Based on Preliminary Animal Studies
Resveratrol is a flavonoid first studied in red grapes and red wine, but now also found to be present in peanuts. In animal studies on resveratrol itself (the purified nutrient given in intravenous form, not the food form), this phytonutrient has been determined to improve blood flow in the brain by as much as 30%, thus greatly reducing the risk of stroke, according to the results of a laboratory animal study published in the Journal of Agricultural and Food Chemistry.
Lead researcher Kwok Tung Lu hypothesized that resveratrol exerted this very beneficial effect by stimulating the production and/or release of nitric oxide (NO), a molecule made in the lining of blood vessels (the endothelium) that signals the surrounding muscle to relax, dilating the blood vessel and increasing blood flow. In the animals that received resveratrol, the concentration of nitric oxide (NO) in the affected part of the brain was 25% higher than that seen not only in the ischemia-only group, but even in the control animals.
The jury is still out on peanuts however, since they contain far less resveratrol than the amounts used in the above study, and also less than the amount provided by red wine. An ounce of red wine can provide as much as 1,000 micrograms of resveratrol, and it almost always provides over 75 micrograms. The same ounce of peanut butter can only provide about 50 micrograms of resveratrol. Still, routine consumption of peanuts or peanut butter might turn out to be significant in terms of the resveratrol provided by this food.
Peanuts Protective, but Pickled Foods Increase Risk of Colon Cancer
A number of studies have shown that nutrients found in peanuts, including folic acid, phytosterols, phytic acid (inositol hexaphosphate) and resveratrol, may have anti-cancer effects. A good source all these nutrients-including the phytosterol beta-sisterol, which has demonstrated anti-cancer actions-peanuts have long been considered a likely candidate as a colon cancer-preventive food.(Awad AB, Chan KC, et al., Nutr Cancer)
Colorectal cancer is the second most fatal malignancy in developed countries and the third most frequent cancer worldwide. In Taiwan, not only has incidence of colon cancer increased, but the likelihood of dying from the disease rose 74% from 1993 to 2002.
Taiwanese researchers decided to examine peanuts' anti-colon cancer potential and conducted a 10-year study involving 12,026 men and 11,917 women to see if eating peanuts might affect risk of colon cancer.(Yeh CC, You SL, et al., World J Gastroenterol)
Researchers tracked study participants' weekly food intake, collecting data on frequently consumed foods and folk dishes such as sweet potato, bean products, peanut products, pickled foods, and foods that contained nitrates or were smoked.
Risk of colon cancer was found to be highly correlated with both peanuts, which greatly lessened risk, and pickled foods, which greatly increased risk, particularly in women.
Eating peanuts just 2 or more times each week was associated with a 58% lowered risk of colon cancer in women and a 27% lowered risk in men.
In women, but not in men, eating pickled foods 2 or more times a week more than doubled the likelihood of developing colon cancer risk for women, increasing their risk 215%.
Practical Tips: To help prevent colon cancer, avoid pickled foods, but enjoy peanuts at least twice each week. In addition to that old stand-by, the PB&J sandwich, try some of the following:
• Spread peanut butter on your morning waffle, whole grain toast or mid-morning crackers.
• Add a tablespoon of peanut butter to your morning smoothie.
• Enjoy a handful of dry roasted peanuts with a glass of tomato juice as an afternoon snack.
• Combine peanut butter, coconut milk, and ready-to-use Thai red or green curry paste for a quick, delicious sauce. Pour over healthy sautéed vegetables. Use as a cooking sauce for tofu or salmon.
• Toss cooked brown rice with sesame oil, chopped peanuts, scallions, sweet red pepper, parsley and currants.
When purchasing peanut butter, be sure to read the label. Hydrogenated(trans-) fats and sugar are often added to peanut butter. Buy organic and choose brands that contain peanuts, salt-and nothing else!
0 comments:
Post a Comment