|
|
|
HONOLULU, HAWAII. A high intake of fruit and vegetables has
consistently been linked to a lower risk of lung cancer. Early
research pointed to beta-carotene as the protective component, but
its role as such has not been confirmed in more recent research.
Now medical researchers at the University of Hawaii provide
convincing evidence that it is the flavonoids contained in many
fruits and vegetables that protect against lung cancer.
Their study involved 582 patients with lung cancer and 582 age-,
sex-, and ethnicity-matched controls. All participants were
interviewed at home and filled out a food-frequency questionnaire
that tabulated their intake of 242 different foods in the year
prior to their diagnosis of cancer or in the case of controls, in
the year prior to their interview. As expected smoking status was
found to be the main risk factor for lung cancer with there being
three times as many smokers in the cancer group as in the control
group. After adjusting for smoking and intakes of beta-carotene
and saturated fats the researchers found a clear inverse
correlation between the intakes of onions, apples, and white
grapefruit and the risk of lung cancer. Study participants who
consumed 20 grams of onions or more per day had half the risk
compared to participants whose intake was 7.5 grams/day or less.
The protective effect of onions was particularly impressive in the
case of squamous cell carcinoma where heavy onion eaters had only
one-tenth the risk of less enthusiastic onion consumers. Apple
eaters consuming 50 grams/day (about 1/3 apple) or more lowered
their risk by 40 per cent compared to participants consuming 2.3
grams/day or less. White grapefruit, but not the pink variety,
also lowered lung cancer risk with participants consuming 10
grams/day having half the risk of those not consuming white
grapefruit at all.
The researchers conclude that quercetin is likely to be the
protective component in onions and apples while naringin is likely
to be the active component in white grapefruit. They do emphasize
though that the strongest protective effect was seen with the
whole foods (apples, onions and grapefruit) rather than with
quercetin and naringin.
|
|
|
|
