A literature search found 19 human studies that were reviewed. Garlic in the diet did not reduce the risk of gastric, breast, lung, or endometrial cancer.
There is very limited evidence for a reduced risk of colon, prostate, esophageal, larynx, oral, ovary, or renal cell cancers.
The potential for prevention of colorectal cancer in the UK.
“We estimate that 31.5% of cancers in men and 18.4% in women could be prevented if reasonable targets with respect to diet (reduced consumption of red meat, increased fruit and vegetables), exercise (30 min 5 days a week), alcohol consumption (3 U a day for men, 2 U for women) and weight control were achieved.”
Energy intake, physical activity, energy balance, and cancer: epidemiologic evidence.
Obesity increases the risk of cancers of
Obesity probably increases cancers of
Impact of nutrition and exercise on cancer survival.
Observational data strongly indicate that obesity, weight gain, and physical inactivity are adverse prognostic factors, although data on diet or supplement use in relation to cancer survival are more limited and inconsistent.
Five flavonoid containing foods (tea, apple, broccoli, onion, and tofu) did not prevent cancer after 11.5 years in over 38,000 women in the Women’s Health Study.
Diet and upper-aerodigestive tract cancer in Europe: The ARCAGE study.
Eating red meat increased upper-aerodigestive tract cancer risk, especially esophageal cancer.
The consumption of fruits, vegetables, olive oil and tea reduced the risk of upper-aerodigestive tract cancer.
Fruit and vegetable intakes are associated with lower risk of colorectal adenomas.
“This study provides additional evidence that high total fruit intake and certain fruit and vegetable intakes may be associated with a reduced risk of colorectal adenomas.”
Intake of fruits, and vegetables in relation to breast cancer risk by hormone receptor status.
A large population-based case-control study from Poland.
An increased level of total fruit intake was associated with a reduced overall risk of breast cancer. This association was stronger for reduced estrogen receptor positive tumors.
Increased vegetable intake did not affect the risk of breast cancer.
Impact of diet on breast cancer risk.
Studies so far have only shown “consistent and strong positive associations” for an increased breast cancer risk with alcohol intake and being overweight.