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Just as wine never wears out its welcome because of infinite variety,
science is ever changing, continually renewed. The same sort of
anticipatory excitement that attends a new vintage is stimulated
by scientific data that furthers our understanding an additional
step. I am intrigued by new reports in strictly selective medical
journals bearing on wines potential ability to protect us from
cancer. It is a good time to review previously established information,
to provide perspective.
First, let us revisit what is known of increased cancer risk associated
with drinking.1 Alcohol (and its first breakdown product, acetaldehyde) is the
only component of wine that may be inculpated, then almost exclusively
when chronically abused. Spirits and beer appear to be associated
with more risk than wine. It is generally accepted that prolonged
excessive consumption of alcohol, especially when combined with
smoking, leads to an increased incidence of aerodigestive cancers
(mouth, throat, larynx, esophagus, perhaps stomach). Chronic liver
damage of any cause (viral hepatitis, alcohol abuse, toxic damage,
as by iron overload) increases the risk of liver cancer. Alcohol
abuse may indirectly and rarely promote pancreatic cancer. The
influence, if any, of even moderate drinking on the risk of breast
and colorectal cancers remains unclear, and, at worst, small.
Information available on possible associations, beneficial or
adverse, between alcohol and other cancers is trivial and immature.
We should factor in the beneficial cardiovascular effects (improved
health, reduced mortality) of moderate drinking. Then, the net
general result is clearly favorable. Individual assessment is
necessary for individual advice.
It appears that the anti-cancer capabilities possessed by potables
reside in wines polyphenolic flavonoids, generally referred to as antioxidants, for their best-known function. Other functions,
in the vine (among which, protection from fungus) and in the drinker
(best known for cardiac protection), are incompletely understood.
Of the dozens of such compounds, quercetin and resveratrol are
most familiar. The cancer-protective effects of the antioxidants
probably work by a multiplex of mechanisms, especially by inhibition
of carcinogenic oxidative reactions promoted by excessive alcohol
and acetaldehyde in the liver and upper aerodigestive tract.
The phenolics of wine are believed to help eliminate infection
of the stomach by Helicobacter pylori, a bacterium that causes
chronic gastritis, most ulcers, and a significant proportion of
cancers of the stomach. They inhibit the reactions that induce
malignant mutations by damaging DNA. They induce the activity
of enzymes that protect DNA and repair damage to our genetic material.
Red-wine solids delay the formation of tumors in mice genetically
engineered to be afflicted with them.
Quercetin-rich diets in China are associated with reduction of
the high frequency of stomach cancer. Quercetin is found in abundance
in grape skins and in allium vegetables (onion, scallion, leek,
shallot, garlic) and broccoli. It has been demonstrated to inhibit
the growth of the cells of leukemia and ovarian and uterine cancers,
and to enhance the effectiveness of cisplatin, a widely used chemotherapeutic
agent.
Resveratrol is esteemed for its likely cardiac protection in humans.
Its mechanisms of cancer protection include modulation of the
inflammatory reactions that may damage tissues and lead to cancer;
promotion of normal cellular differentiation and maturation, the
opposite of cancer growth; inhibition of cancer formation; countering
the unbalanced effects of estrogen, which, when unopposed, may
lead to breast and uterine cancer.
A provocative research paper confirms and elaborates the kind
of antioxidant activity of quercetin that surely has relevance
to both cardiovascular and cancer protection. A main pathway in
the formation of cancer is considered to be repetitive tissue
injury by highly chemically reactive free radicals (not a political
term) and avid oxidants. The study by Huk, et al.,2 demonstrated that quercetin reduced injury to tissue by scavenging
destructive superoxide and by increasing the tissue concentration
of protective nitric oxide.
Another research report is astonishing. It presents direct evidence
that resveratrol causes the death of cancer cells. Clement, et
al.,3 studied the effects of resveratrol on human leukemia cells, breast-cancer
cells, and normal cells. The resveratrol initiated a series of
biochemical events within the leukemia and the cancer cells that
resulted in programmed cell death, a process called "apoptosis."
Normal cells were not harmed. The death cascade proceeded by a
chiefly enzymatic pathway induced by resveratrol, really a tumor
suicide. The novel mechanism, the selective targeting of cancer
cells, and the lack of toxicity to normal cells excite interest
in clinical trials in the prevention and treatment of cancer,
perhaps in combination with other anti-cancer drugs and with immune
defenses against cancer..
I must emphasize that the practical clinical applicability of
this data is unclear, and will take quite some time to determine,
but isn't it fascinating?
Dr. Finkel is Clinical Professor at the Boston University Medical
Center, Chairman of the Committee on Health of the Society of
Wine Educators and writes and lectures internationally on the
interrelationships of wine and health.
REFERENCES:
1. Finkel, HE: In Vino Sanitas? Savage MD: Society of Wine Educators,
1998.
2. Huk I, Brovkovych V, Nanobashvili J, et al: Bioflavonoid quercetin
scavenges superoxide and increases nitric oxide concentration
in ischaemia-reperfusion injury: an experimental study. Br J Surg
1998; 85:1080-1085.
3. Clemont M-V, Hirpara JL, Chawdhury S-H, et al: Chemopreventive
agent resveratrol, a natural product derived from grapes, triggers
CD95 signalling-dependent apoptosis in human tumor cells. Blood
1998; 92:996-1002. |
