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
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
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%
, 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
Epidemiological and experimental evidence suggests phytosterols have a
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
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 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 protecting against 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
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 lowering blood cholesterol levels.
A recent study from Penn
shows that diets that include 2-3 servings daily
of peanuts or peanut butter lowered cholesterol by 11%
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
Overall, the peanut diets reduced the risk of cardiovascular disease by
21%, whereas a low-fat diet reduced the risk by only 12%.
Our recipe for Continental Peanut Meatloaf is a
delicious way to get extra peanuts into your life.
We have lots more ideas in our
Nutrition scientists have long known about the health benefits of plant-based
diets. Besides phytochemicals, some plant foods also contain healthy
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
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.
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.
Prineas, R J; Kushi, L H; Folsom, A R; Bostick, R M. Letter to the editor,
New England Journal of Medicine. 1993:329:359.