Western diet linked to breast cancer

Western diet characterized by high fat and high cholesterol may promote the growth and spread of breast cancer, a study in the Jan 2011 issue of the American Journal of Pathology suggests.

The study led by Philippe G. Frank PH.D. at Thomas Jefferson University showed mice fed a Western style diet developed twice as many tumors and had 50 percent larger size of tumors, compared with those fed with a low fat and cholesterol free diet.

Western diet has been linked to a variety of cancer.  The authors reported in the December issue of The same journal that cholesterol increases risk of prostate cancer.

Cholesterol is only found in animal-based foods. Plant-based foods contain no cholesterol and are associated with lower risk of a range of malignancies. 

For the current study, PyMT mice were used to study the effect of the western diet on the risk of breast cancer in the animals.  

Specifically, Dr. Frank et al. gave PyMT mice a diet containing 21.2 percent fat and 0.2 percent cholesterol, which is typical of Western diet and control mice a diet with only 4.5 percent fat and negligible amounts of cholesterol. 

Mice fed the high fat high cholesterol diet developed twice as many cancers and the sizes of tumors found in these study mice were 50 percent larger, compared with mice fed a low fat and no cholesterol diet.

In addition, mice on the high fat high cholesterol diet were more likely to spread their cancers to other organs like the lungs, compared with the control mice.  

The researchers found evidence that suggests cancers found in mice fed high fat high cholesterol were more likely to be in an advanced stage, compared with those in the control mice.

Interestingly, mice fed the "western style diet" had lower levels of cholesterol in their blood, which the researchers said indicated that a cancer needs cholesterol for its growth.

It has been observed for long that women in poor countries where meat and dairy products are not readily available are at much lower risk of breast cancer, compared with their counterparts in the West where the high fat and high cholesterol diet is commonly used.

One thing readers may need to know is that simply reducing intake of fat and cholesterol may not be enough to reduce the risk of breast cancer.  

Another study led by Martin L.J and colleagues in Canada conducted a randomized controlled trial in 4,690 women with extensive mammographic density and demonstrated that a diet containing 15 percent calories from fat and 65 percent of calories from carbohydrates did not reduce the breast cancer risk.

Unfortunately, it was unknown what types of carbohydrates were used by the subjects. In fact, not all carbohydrates are made the same.  

According to Dr. Collin T. Campbell, nutrition professor at Cornell University said plant-based diet including whole grain products, which contain high amounts of carbohydrates, actually reduce the cancer risk.

Breast cancer in many cases are preventable, numerous studies have suggested.  Foodconsumer.org has extensively reported on this subject.

A recent study in the Nov 2010 issue of Asian Pacific Journal of Cancer Prevention shows subjects following low fat and non-alcoholic beverage patterns were at 70 and 55 percent reduced risk of breast cancer, compared with those high fat diet users and alcoholic drinkers, respectively. 

On the other hand, Ronco AL and colleagues from Facultad de Medicina in Uruguay found fatty cheese dietary pattern, fried white meat and Western dietary pattern was linked with 317 percent, 128 percent and 113 percent increased risk of breast cancer, respectively.

In the United States, breast cancer is diagnosed in 175,000 women each year and the disease kills about 50,000 annually, according to the National Cancer Institute.  One in seven women will get the disease in their lifetime.

David Liu and editing by Aimee Keenan-Greene