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Low-fat diet and prevention of breast cancer - why the evidence is elusive
In 2006, the project results more largest in the world of dietary fat have been published (see reference at end). He was a U.S. government funded study of 48,835 postmenopausal women in a trial randomized clinical prospective multicenter Health Initiative called the women randomly controlled diet modification of First Instance. The study was conducted from 1993 to 2005 in 40 centers across the country. The volunteers were randomly assigned to either a group of low-fat diet (19,541 women) or diet group Regular (29,294 women). After eight years of monitoring, this study on a large scale and cost has not found significant differences in the incidence of breast cancer among postmenopausal women who were invited to adopt a diet low in fat and those that followed eating a normal diet. Moreover, the results suggest that switching to a diet low in fat may reduce the risk of breast cancer for women with a diet high in fat to begin with.
According to most experts, the following may have some reasons why this study showed no significant advantage:
1) Not many women reached the target of 20% of intake fat. This "low fat" diet have not been really low in fat. Like most women do not meet the goal of reducing the content fat, this study showed May Only intervention approach did not work. This is not real proof of a diet low in fat "does not help protect against cancer breast. Get that 20% of calories from fat is very hard to do. This means that if you eat 2,000 calories per day, only 400 calories can come from from fat. It is therefore not surprising that less than one third of women have achieved this goal after the first year and only 14% continued to reach the goal after six years. Because so few women in the study, this means that do not really know how a low-fat diet affects the risk of breast cancer.
2) The diets were self-reported and infrequent and May make them unreliable. This study was based on written reports from women about what they ate, what can not be an accurate reflection of the contribution TRUE. This work has been done on occasion. No daily food diary or journal has been made and tested. Most we are not proud to admit in an interview or a questionnaire that we have violated the rules and not have adhered to the prescribed diet. "This thing can be a tendency to underestimate the actual amount of fat eaten.
3) Other changes besides the low-fat diet. The study does not distinguish between the effect of reducing the amount of fat consumed vs. the effect of increasing fruit and vegetables. Group of women low-fat diet ate two daily servings of fruits and vegetables than women in the Force of the regular diet group and nearly one more serving of grains.
4) Length of time on the track. While 48,835 women is a lot of people, eight years coaching is not long. Eating a low-fat diet for 15 or 20 years can provide greater benefits and demonstrate a closer relationship between dietary fat and risk of breast cancer.
5) The total mass basis. In this study, 74% Women were classified as overweight by BMI at baseline. Also, do not really know if a diet low in fat may offer benefits to women who were normal weight at first.
6) All post-menopausal women. It may be that dietary fat plays a greater role in the diet of most young, premenopausal women. It is logical that their diet during the first 50 years of his life might affect your risk of cancer in the second half of his life. The study does not address this issue.
7) The type of fat is not specified. There are three main types of fats: saturated, monounsaturated and polyunsaturated fats. In this study, women were asked only to reduce fat. They were not invited to examine the different types of fat or says that reducing saturated fat can offer more health benefits that unsaturated fats and reduce. Saturated fats are found only in animal foods and types of fats that increase cholesterol in the blood. Trans fats (also called trans fats) are the fat man. (Vegetable oils are modified to form margarine and shortening, which are the trans fat.) The trans fats are also added to packaged foods. Saturated fats raise blood cholesterol "bad" (low-density lipoprotein of LDL) and lowering "good" cholesterol (high density lipoprotein or HDL). Mono-unsaturated and polyunsaturated fats are in plant foods like vegetables, nuts and cereals and oils made from these fruits and seeds (canola, corn, soy). Omega-3 and omega-6 are polyunsaturated fatty acids. In addition to the vegetables, nuts and grains, omega-3 and omega-6 fatty acids are present in cold water fish such as tuna, salmon and mackerel. Some studies have shown that eat foods that are mono-or poly-unsaturated fats can help reduce levels of bad cholesterol. Mono and polyunsaturated fats may also keep your triglycerides low. Triglycerides are a form of blood fat.
None of the women in each group were invited to change their health-related behaviors such as exercise, drinking or smoking. These known risk factors for breast cancer have been left without control and can hide any benefit from eating less fat.
9) This study focuses on a diet low in fat, this is nothing but a state of overweight or obese normal weight. Eat less fat while being constantly on May fats help from anyone! Since this study cost nearly half a trillion dollars is unlikely that the intervention of another scale clinical lifestyle that would do it again soon, especially in the current U.S. economy.
Reference: Prentice RL, et al. Under standard dietary fat and risk of invasive breast cancer: Women's Health Initiative Randomized Controlled Dietary Modification Trial. Journal of the American Medical Association, volume 295, pages 629-42, 2006.
About the Author
Dr. Mai Brooks is a surgical oncologist/general surgeon, with expertise in early detection and prevention of cancer. More at www.drbrooksmd.com, thecancerexperience.wordpress.com and progressreportoncancer.wordpress.com.
"Breast Cancer Journal" author Juliet Wittman & RC Cohen
