Does Saturated Fat Promote Breast Cancer?
Studies document a definitive relationship between diets higher in saturated fat and elevations of LDL cholesterol.1-5 In spite of efforts of the dairy and meat industry to support and produce dubious, highly promoted research that exonerates their products and to use their media partners to confuse the public, the reality is that overwhelming evidence exists that diets high in animal products are exceedingly dangerous, placing the public at an increased risk of a premature death. The advocates of popular diet programs, such as Atkins, Dukan, Paleo and others saturate the internet with propaganda aiming to absolve animal products as a cause of heart disease, but heart disease is not the only concern. Not much attention has been paid to the data suggesting that saturated fat (or saturated fat-rich foods) may impact cancer risk. Two new studies have added more convincing evidence by reporting a link between saturated fat and breast cancer.
One study investigated the intake of different types of fats with respect to the risk of different subtypes of breast cancer (breast cancers are divided into subtypes based on whether the tumor cells contain receptors for certain hormones such as estrogen and progesterone). Dietary information was collected from 300,000 women living in 10 different countries throughout Europe, who were then followed for 11.5 years. The women with the highest intakes of saturated fat showed a greater risk of two subtypes of breast cancer: ER+PR+ (estrogen receptor and progesterone receptor-positive) and HER2- (human epidermal growth factor receptor 2 negative).6 This suggests that saturated fat could have some influence on the development of HER2- breast cancer and ER+PR+ breast cancer, which is a very common subtype; about 80 percent of breast cancers are positive for the estrogen receptor, and 65 percent of those are also positive for the progesterone receptor.7 A second study, based on data from the Nurses’ Health Study II, collected dietary information from 26-45 year old women and followed them for 20 years. Similarly in this study, a higher intake of saturated fat was associated with greater risk of breast cancer. An interesting point in this study, is that their data suggested that the saturated fat source likely responsible for the link was red meat.8 These results are in agreement with the conclusion of a 2003 meta-analysis of 35 studies, which reported that the highest levels of saturated fat intake in women were associated with a 19 percent increase in breast cancer risk, and also implicated meat as the food most likely to be responsible.9
A question arises out of these results: does saturated fat promote cancer? Or is saturated fat just a marker for a cancer-promoting substance in saturated fat-rich foods? There is very limited evidence that saturated fat itself increases cancer risk. A saturated fat-rich diet may promote insulin resistance, which could be a contributing factor.10 But it is likely that a combination of factors in saturated fat-rich foods, red meat in particular, is responsible for the increase in cancer risk:
- In addition to saturated fat, red and processed meats also contain a significant amount of arachidonic acid, an omega-6 fat shown to promote breast tumors in animals, likely by promoting inflammation.11-14
- Carnitine (abundant in red meat) and choline (abundant in eggs, dairy, and meats) are metabolized by gut bacteria into a pro-inflammatory compound called trimethylamine-N-oxide (TMAO) that may contribute to the development of cancers.15-17
- Eating red meat exposes us to dietary carcinogens such as N-nitroso compounds and heterocyclic amines.18-21
- The heme iron content of red meat is also problematic, since excess iron causes oxidative stress.22, 23
- Finally, dietary animal protein increases circulating levels of insulin-like growth factor 1 (IGF-1), a hormone that promotes tumor cell growth and is associated with an increased risk of cancer.24, 25
Regardless of the specific actions of saturated fat, the saturated fat-rich foods common in the standard American diet, red meat in particular, contains numerous disease-promoting substances. However, greens, beans, onions, mushrooms, berries, and seeds (G-BOMBS) have documented breast cancer-preventive properties. By focusing our diet on G-BOMBS and other vegetables and minimizing animal foods, we provide the body with the tools it needs to build the best possible defenses against cancer.
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