Peanuts and Your Health
Recent discoveries by nutritionists have found what we've always suspected: peanuts are actually good for your health!
According to the latest research, a diet rich in peanut products can reduce your cholesterol, lower your risk of heart disease andprovide protection against cancer.
The material below comes from notes published by The Peanut Institute, a US-based non-profit organisation that supports nutrition research and develops educational programs to encourage healthful lifestyles. It outlines the results of the most recent research that's been undertaken in this field, most of it conducted in 1999 and 2000:
Nutrition scientists are discovering more and more components of plant-based foods that may provide health benefits.
One of these is phytosterols, which are natural chemicals found in plants.
Phytosterols are found in high concentrations in some plant oils, seeds and legumes such as peanuts.
They're also found in lower concentrations in fruits and vegetables.
Recent research has shown that phytosterols:
- Inhibit cancer growth, and...
- Protect against heart disease, and...
- May offer protection against colon, prostate and breast cancer
Phytosterols (PS) include both plant sterols and stanols, which differ in their chemical structures. The three most common forms of phytosterols in foods are beta-sitosterol, campesterol and stigmasterol.
Phytosterols are the equivalent of animal cholesterol in the body but they act very differently. One difference is that phytosterols are absorbed at a much lower rate than cholesterol. Phytosterols are absorbed from the blood into the body at a rate of 5% to 10%, whereas cholesterol is absorbed at a rate of 50%1
Recent research has identified the amount of beta-sitosterol (SIT) in peanuts and peanut products. SIT is the most widely found phytosterol in foods and new research shows it may help protect against colon, breast and prostate cancer. Researchers at the State University of New York in Buffalo examined the SIT content of several peanut products. They found that snack peanuts contain about 65mg SIT per 100 gms, while peanut oil contains about 190mg per 100 gm, making it a good source of SIT as well2
In fact, refined (or pure) peanut oil contains about 38% more protective SIT than refined olive oil2
Dr Atif Awad, co-investigator of the study and professor of nutrition at the State University of New York at Buffalo, said "studies from our laboratory and others suggest that plant sterol consumption offers protection from colon, breast and prostate cancer. Therefore, identifying popular foods such as peanuts, peanut oil, peanut butter and peanut flour as good sources of SIT may provide major health benefits for many people.
As plant components, phytosterols may offer protection against cancer by several different means. These include inhibiting cell division, stimulating tumor cell death and modifying some of the hormones that are essential for tumor growth3
Epidemiological and experimental evidence suggests phytosterols have a protective effect. Long term studies show an association between the amount of plant sterol consumed in the diet and developing cancer.
For example, there is a much higher incidence of colon, prostate and breast cancers in Western societies compared to Asian societies, where they consume 3 to 4 times the amount of phytosterols. The Western diet contains about 80 mg PS/day, while vegetarian diets contain 345mg PS/day and Japanese diets contain 400mg PS/day 3
In an experimental study recently published in Anticancer Research, mice with human cancer cells were fed either a phytosterol diet or a cholesterol diet.
Tumor size in animals fed phytosterols were 33% smaller and had 20% few shifts of cancer cells to lymph nodes and lungs than the cholesterol diet group.
The study concludes: "Phytosterols, which can easily be incorporated into our diet, may offer a relatively simple and practical means for retarding growth and metastases of breast cancer cells"
Peanuts are also one of the few foods that contain the plant chemical resveratrol. This sterol has been associated with reduced cardiovascular disease and reduced cancer risk.
Resveratrol is most widely known for its presence in grape skins and red wine and may be one of the compounds responsible for the known health benefits of red wine consumption.
Dr Tim Sanders and his team of researchers at the US Department of Agriculture found that peanuts have a significant amount of resveratrol. The average amount of resveratrol in one ounce of commonly eaten peanuts without the skin (15 whole peanut kernels) is 73 ug4,5
This means that ounce for ounce, peanuts contain almost 30 times as much resveratrol as grapes.
Traditionally, scientists have looked at plant sterols for their benefits in preventing heart disease. Phytosterols were first recognised in the 1970s for their ability to absorb dietary cholesterol in the blood, thereby protectingagainst cardiovascular disease.
Phytosterols lower cholesterol in two ways:
- First, they block the absorption of dietary cholesterol that is circulating in the blood.
- Second, they reduce the reabsorption of cholesterol from the liver, which the body naturally produces.
So whether your cholesterol is high because of dietary habits, genetics or both, eating foods with phytosterols can help lower blood cholesterol levels.
Food companies have started adding different plant sterols and stanols to foods such as margarines and salad dressings to provide this blood cholesterol-lowering benefit. Advertisements encourage consumers to eat three servings of these fortified foods every day to lower cholesterol by 10% to 15%.
Peanuts and peanut products are unique whole foods that naturally contain phyto-chemicals. They also contain heart-healthy monounsaturated fat, which has been linked to loweringblood cholesterol levels.
A recent study from Penn State University shows that diets that include 2-3 servings daily of peanuts or peanut butter lowered cholesterol by 11% to 14% 6
The researchers compared three higher-fat diets - one with peanuts and peanut butter, the second with peanut oil, and the third with olive oil - to the average American diet and a low-fat diet.
They found that the three diets all rich in monounsaturated fat all lowered total cholesterol, LDL (bad) cholesterol and triglyceride levels, and didn't lower beneficial HDL cholesterol levels.
One factor that might contribute to these results, in addition to other essential nutrients and healthy fatty acids, are the many plant chemicals found in peanut products.
Overall, the peanut diets reduced the risk of cardiovascular disease by 21%, whereas a low-fat diet reduced the risk by only 12%.
Nutrition scientists have long known about the health benefits of plant-based diets. Besides phytochemicals, some plant foods also contain healthy unsaturated fat.
Replacing even a small amount of the saturated fat in your diet with monounsaturated fat can have a big effect on health. Try new dishes with peanuts, beans or seeds instead of cheese and meat, or spread peanut butter on your morning bagel instead of cream cheese or butter.
The finding that peanuts contain phytosterols that are thought to provide health benefits is consistent with epidemiological studies. Researchers at Lorna Linda University, the Harvard School of Public Health and the Iowa Womens Study found that in the populations studied, frequently eating small amounts of peanuts, peanut butter and nuts helped reduce the risk of heart disease by as much as 50% 7,8,9
Many other nutrients are thought to contribute to heart healthfulness are found in peanut products. For example, peanuts and peanut butter are an excellent food source of Vitamin E.
They also provide approximately 2 grams of fibre per ounce, and compared to many other foods have relatively high amounts of folic acid, thiamine, niacin, copper, manganese, phosphorus, magnesium and zinc.
- Awad et al. Dietary Phytosterol Inhibits the Growth and Metastasis of MDA-MB-231 Human Breast Cancer Cells Grown In SCID Mice. Anticancer Research. 2000:20:821-24
- Awad et al. Peanuts As a Source Of B-sitosterol, A Sterol With Anticancer Properties. Nutrition and Cancer. 2000:36(2):238-41
- Awad et al. Phytosterols as Anticancer Dietary Components: Evidence and Mechanism of Action. The Journal of Nutrition. 2000:130:2127-30
- Sanders et al. Occurrence of Resveratrol in Edible Peanuts. Journal of Agricultural and Food Chemistry. 2000:48(4):1243-6
- Lamuela-Raventos, RM et al. Direct HPLC Analysis of cis- and trans- Resveratrol and Piceid Isomers on Spanish Red Vitisvinitera Wines. Agricultural Food Chemicals. 1995:43:281-83
- Kris-Etherton, PM et al. High-monounsaturated Fatty Acid Diets Lower Both Plasma Cholesterol and Triacylglycerol Concentrations. American Journal of Clinical Nutrition. 1999:70:1009-15
- Fraser, G; Sabate, J; Beeson, L W; Strahan, MTA. Possible Effect of Nut Consumption and Risk of Coronary Heart Disease. Archives of Internet Medicine. 1992:152:1416-24
- Hu, FB; Tampler, M J; Manson, J E; Rimm, E; Colditz, G A; Rosner, B A; Speizer, F E; Henneckens, C H; Willett, WC. Frequent Nut Consumption and Risk of Coronary Heart Disease In Women: Prospective Cohort Study. British Medical Journal. 1998:317:341-45
Prineas, R J; Kushi, L H; Folsom, A R; Bostick, R M. Letter to the editor, New England Journal of Medicine. 1993:329:359.