| Nutrition scientists are discovering 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
-
Protect against
heart disease, and
-
May offer
protection against colon, prostate and breast cancer
Phytonutrients Are
Plentiful In Peanuts
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 well 2
In fact,
refined (or pure) peanut oil contains about 38% more protective SIT than
refined olive oil 2
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.
Easy Ways To Add
50mg of SIT To Your Diet
| Amount |
Product
|
Idea |
| 1 oz
|
Peanut
Oil |
Saute
vegetables! Combine with balsamic vinegar and herbs for a marinade for chicken
breasts. |
| 1.2 oz
|
Peanuts
|
Grab
a small handful! |
| 1.3 oz
|
Peanut
Butter |
Just
over 2 tbsp - perfect for a sandwich! |
| 4 oz
|
Peanut
Flour |
Substitute
for half the white flour in bread and cookie recipes |
Phytosterols and
the Cancer Connection
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
growth 3
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"
Resveratrol: 30 Times
The Power Of Grapes!
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 ug 4,5
This means
that ounce for ounce, peanuts contain almost 30 times as much resveratrol
as grapes.
Phytosterols and
Heart Disease
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
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%.
Health Benefits Of
Monounsaturated Fats
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
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%.
High Nutrient Value
In Complex Plant Foods
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.
References
-
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.
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