With several studies showing a relationship between fat intake and breast cancer, it is quite possible that the problem isn’t fat itself, but overall nutrition; people who eat more may be more susceptible to breast cancer. Over nutrition may also correlate with some of the other risk factors; females with lower food intake stay thinner and often begin menstruating later than more heavily nourished girls. People who eat more also tend to be those who can afford to – those with an overall higher standard of living, who appear to be at greater risk of breast cancer.
If fat intake does indeed increase the risk of developing breast cancer, what makes it happen? There have been many theories regarding this. Some researchers think it changes the metabolism of estrogen. According to a study, people with a high fat diet tend to have more estrogen in their blood and a lower urine excretion of this hormone. Vegetarians who eat dairy foods excrete more estrogen, leaving less in the blood than people on macrobiotic diets. Macrobiotic diet involves the consumption of organically grown whole grain cereals, legumes, vegetables and fruits, in meals according to the principle of balance between yin and yang properties, in contrast to scientific dietary guidelines. Fat cells in the body can synthesize estrogen, so it is also possible that if you are obese you have an oversupply of estrogen in your body, which could heighten your vulnerability to cancer. However, studies aimed at confirming this hypothesis have been inconsistent.
It is also possible that cancer cells grow faster in an environment with a lot of over nourished cells and the fatter you are the more such cells there are for the cancer cells to grow with. There is also some evidence that among women with breast cancer those on low fat diets have a better prognosis than those on high fat diets.
It may be that fiber, rather than fat, is the more essential element. Oftentimes diets very high in fiber are very low in fat. It may be that with a low fat diet, it’s the fiber or the carbohydrates or the vegetables, which have replaced fat are the ones responsible for reducing cancer susceptibility. Several studies show that soy protein may be protective. Perhaps the problem is not that the Japanese are starting to eat fat, but that they stopped eating tofu! There is also growing evidence that certain vegetables, antioxidants in particular, which contain vitamins A, C and E, may be protective against breast cancer.
Vitamin A from vegetables (beta carotene) has shown in various studies to decrease the incidence of several cancer types, including lung cancer. A recent study using fenretinide, a form of vitamin A, in women who had had breast cancer showed no decrease in secondary cancers (metastasis), although there was a hint that there may be different, more beneficial effects in premenopausal women than their postmenopausal counterparts. Vegetables with vitamin A include broccoli, kale, carrots and lettuce. Folic acid and vitamin C appear to be good against all types of cancer.
You may do well to encourage your kids to spend a little less time eating fast foods and to eat a bit more low fat, nutritional food high in vitamins. However, it is not wise to expect miracles. Even if dietary change does have an effect, it is likely to be a small one.