Health Benefits of Grapes

Good News from the Grapevine

Grapes can be eaten fresh or dried (raisins), while grape juice
is a favorite beverage. Although seedless grapes are highly
sought after for table grapes, the absence of seeds does
diminish the phytochemical content of the grape. Grapes
are also used for making jam and jelly.

Currants are dried Zante grapes, but the name currant
has also been applied to two berries, black currants and
red currants, that are unrelated to grapes. Sultanas were
originally raisins derived from a lighter grape of Turkish
origin.

Concord grapes

Grape seeds provide an edible oil. Grape seed extract is
also available as a supplement. It is claimed to strengthen
capillary walls, so that it finds use in the treatment of
venous insufficiency, and edema following surgery. It
also reduces the risk of blood clots.

Many of the health benefits attributed to red/purple
grapes are due to the pigments that are concentrated
largely in the skin and seeds, which have about 100
times higher level than the pulp of the grape. Anthocyanins
tend to be the main polyphenolics in red grapes while the
catechins are the more abundant phenolic in white grapes.
The phenolic content of grape skins depends upon the
variety, the soil, climate, geography, cultivation practice,
and exposure to fungal infections. Grapes are also rich in
ellagic acid, a potent flavonoid that helps fight cancer.

Grapes and grape juice function in different ways in the
cardiovascular system. The pigments in red, purple and
black grapes protect the cardiovascular system by a
number of mechanisms that include the suppression of
blood clots, inhibition of LDL cholesterol oxidation,
reduced homocysteine levels, and anti-atherosclerotic
properties. Grapes stimulate endothelial nitric oxide
production which induces relaxation of the blood vessel
walls, and a reduction in blood pressure levels. Recently,
it was shown that a Concord grape extract lowered
LDL cholesterol, raised HDL cholesterol, and decreased
plasma inflammatory biomarkers.

Resveratrol (3,5,4'-trihydroxy-trans-stilbene), a
dietary constituent found in grapes exerts a wide variety
of pharmacological activities. Resveratrol is as an effective
agent for cancer chemoprevention due its ability to block
many steps in the carcinogenesis process. Resveratrol
contained in red grapes and berries has been shown to
inhibit prostate cancer cell growth, induce apoptosis,
influence interleukin-6, and exert immuno-modulatory
effect on mouse lymphocytic leukemia. One of the possible
mechanisms for the protective activity of resveratrol is
by down regulation of inflammatory responses.
Resveratrol also inhibits the nuclear transcription factor,
NFkappaB.

Anthocyanins and proanthocyanidins are two
groups of polyphenolics in Concord and similar grape
juices. These substances show cancer preventive and
anti-proliferative properties and can detoxify the
activity of some cancer-causing substances. Concord
grape juice can protect healthy breast cells from DNA
damage caused by a chemical carcinogen. Grape juice
also suppresses the growth and development of breast
cancer cells in laboratory animals given chemically
induced tumors. The grape juice reduced both mammary
tumor size and the number of tumors per animal. The
pigments in grape juice also improve immune
responsiveness.

VINEYARD

Promising data suggests the use of grape juice to
promote brain health and delay neurodegenerative
diseases. Participants that drank purple grape juice
and similar fruit juices three times a week were about
70% less likely to develop Alzheimer's disease. When
laboratory animals were fed Concord grape juice they
showed significantly improved scores on memory and
coordination tests.

Author: Winston Craig, MPH, PhD, RD.