Cancer

The evidence linking dietary fat to cancer is inconclusive. The case looks strong when we compare cancer rates of countries: overall cancer rates are generally higher in countries with high fat intake, and lower in countries where people eat less fat. But in population studies within those countries in Asia, Europe, United States and Latin America, the evidence linking fat to cancer is weaker.

The Nurses Health Study followed more than 121,000 women for 14 years and found no evidence that higher total fat intake was associated with an increased risk of breast cancer. These results call into question theories that link dietary fat with other cancers. Red meat intake, but not total fat, may be related to colon cancer, and animal fats may be related to prostate cancer. Calorie intake may be a more important factor than fat intake.

Phases development of Cancer
Cancer develops in a multistage process that occurs over many years. There are typically three phases of development:

1. initiation, when something alters a cell's genetic structure and prepares it to act abnormally during later stages

2. promotion, a reversible stage when a chemical or other factor encourages initiated cells to become active, and

3. progression, when promoted cells multiply and may invade surrounding healthy tissue

Evidence suggests that between 30 and 40 percent of cancers are due to poor food choices and physical inactivity, although the role of nutrition and diet in cancer development is complex. Some dietary factors may act as promoters; many others may have protective roles, blocking the cellular changes in one of the developmental stages.

When cancer is chemically induced in the rodents traditionally used as research subjects, high intake of fat, calories, and omega 6 fatty acids all appear to promote tumor growth. Just how relevant these studies are to humans is unclear and uncertainty, and any conclusions about the relationship between dietary fats and cancer remain controversial till now.

Excessive fat intake has been linked to obesity, heart disease, and cancer. There is a major public heath effort to reduce intake of fat, saturated fat, and cholesterol. Cholesterol which lowering diets have changed over the years, with somewhat less emphasis on reducing dietary cholesterol, and more on reducing fats and saturated fats, and increasing fruits, vegetables, and whole grains. The evidence linking dietary such as fats with cancer is less clear, but many other dietary factors are important in reducing risk.