Is a diet deficient in fruits and vegetable risk factors for cancer?
Although fruits and vegetables supply less than 5% of total energy intake, the concentration of micronutrients in these foods is greater than in most others. They are rich in Antioxidants, Minerals, Fiber, Potassium, Carotenoids, Vitamin C, Folate and other vitamins. Consumption of fruits and vegetables appears to be less important in cancer prevention than previously assumed. With fortification of breakfast cereal, flour, and other staple foods, the frequent consumption of fruits and vegetables has become less essential for cancer prevention. Though, high consumption of fruits and vegetables during childhood and adolescence could be more effective in reducing cancer risk than consumption in adult life due to the long latency of cancer manifestation.
What is the protective role of carotenoids and lycopene?
How effective are soy products and nuts in cancer prevention?Soybeans contain isoflavones, phyto¬estrogens that compete with estrogen for the estrogen receptor. In Asian countries, which have a high consumption of soy foods, breast cancer rates have been low. Soy consumption may affect estrogen concentrations differently depending on the endogenous baseline level. Studies have shown that there is a modest decrease in the risk of breast cancer with soy consumption, with childhood consumption being more effective. In a recent meta-analysis of 18 epidemiologic studies, including over 9,000 breast cancer cases, frequent soy intake was associated with a modest decrease in risk (odds ratio = 0.86; 95% CI, 0.75 to 0.99). Wu et al. observed that childhood intake of soy was more relevant to breast cancer prevention than adult consumption. Nuts are rich in unsaturated fatty acids, high-quality protein, fiber, vitamins (e.g., folate, niacin, and vitamin E), minerals (e.g., potassium, calcium, and magnesium), and phytochemicals (e.g., carotenoids, flavonoids, and phytosterols). They have anticarcinogenic, anti-inflammatory, and antioxidant properties. Studies have shown their consumption to reduce the mortality with breast and pancreatic cancer. In two large, independent cohorts of nurses and other health professionals, the frequency of nut consumption was inversely associated with total and cause-specific mortality, independently of other predictors of death for breast cancer and pancreatic cancer.
What is the role of dietary fiber?
Dietary fiber contains plant polysaccharides and lignin which are resistant to hydrolysis by the digestive enzymes. They have the following effects-
- “Bulking” effect, which reduces colonic transit time
- Binding of potentially carcinogenic luminal chemicals.
- Fiber may also aid in producing short-chain fatty acids that may be directly anticarcinogenic
- Fiber may induce apoptosis.