Abstract:
Breast cancer is a growing problem that is affecting more and more individuals worldwide. The number of breast cancer occurrences is increasing and there may be an association between diet during adolescence and the risk of breast cancer. The objective of the study is to determine if diet during adolescence affects breast cancer risk. The studies utilized food-frequency questionnaires to analyze diet during adolescence and the risk of breast cancer. The main finding of the studies indicates that high red meat intake during adolescence is associated with increased breast cancer risk, whereas adolescence intake of poultry, plant-based proteins and fiber were found to decrease breast cancer risk. The risk of breast cancer decreases when one serving of red meat is substituted with one serving of poultry, fish, or legumes. The studies indicate that diet during adolescence impacts the breast cancer risk during adulthood. The area of research is still relatively new and further research needs to occur. Dietary intake during adolescence affects the risk of breast cancer; with this information diet during adolescence can be modified to decrease the risk of breast cancer.
Introduction:
Breast cancer is defined as a mutation where breast tissue cells are constantly proliferating without a point of termination. Breast tissue is vulnerable to effects of environmental factors and carcinogens, especially during the duration of the first occurrence of menstruation to the completion of the first pregnancy, where breast tissue is rapidly growing and dividing. Breast cancer is a disease that mostly affects women. Although it is rare, men can develop breast cancer. In 2013 in the United States, 230,815 women and 2,109 men were diagnosed with breast cancer. This is a large number of people impacted by the disease and the numbers are continuing to rise each year.
Food is fuel for the body. The nutrients that are provided with the consumption of food help the body navigates its growth and development. There are foods that are known to increase risk of diseases such as trans-fat and the link to cardiovascular disease. Some foods are known to promote health such as folic acid and fetal development. There seems to be correlation between diet and health risks. The risk of breast cancer may be affected by adolescence dietary intake. The purpose of this literature review is to analyze several research studies to examine the correlation between diet during adolescence and the risk of breast cancer.
Animal Protein Intake and Breast Cancer Risk:
The study between diet and breast cancer is still relatively new. Studies examined the association between meat intake and breast cancer, but there was no strong evidence to support the association between the two factors. There is a concern regarding the increased red meat intake and the risk of diseases. For example, high red meat intake increases the risk of cardiovascular disease. Researchers are looking for the answer to the questions, “Is adolescent meat intake associated with the risk of breast cancer?” and “Does the type of meat matter?” Several studies examined the correlation between adolescent meat intake and the risk of breast cancer.
The study done by Farvis and fellow researchers examined the association between red meat intake and breast cancer risk. The researchers conducted an investigation of the Nurses’ Health Study II cohort of women who completed a food frequency questionnaire (FFQ) about diet during adolescence. The participants were women between the ages of thirty-three and fifty-two who completed a detailed 124-item food frequency in 1998 regarding their diet between 1960 and 1980, which would be approximately the time period in which they were in high school. In the study, red meats included both processed and unprocessed meats such as beef, pork, hot dogs, bacon, etc. The results of the study showed that of the 44,231 participants, 1,132 of them were diagnosed with invasive breast cancer. For the premenopausal women group, those that had higher red meat intake during adolescence had a statistically significant greater breast cancer risk compared to the adult red meat intake, which did not change the association. The results of the study are significant to the public because it shows that high intakes of red meat during adolescence will affect premenopausal breast cancer risk.
Red meats present an association between adolescent diet and breast cancer risk, but it triggered researchers to question, “Is this the case with all types of animal based protein sources?” The different types of meat have different composition and researchers expected that the intake of different animal-based protein sources would affect the risk of breast cancer differently. Within the same study, researchers examined the associated between adolescent dietary intake of poultry and the risk of breast cancer. The results showed that among all of the participants, those with a higher poultry intake during adolescence had the lower breast cancer risk. Substituting one serving of red meat with other protein sources, such as poultry, fish and legumes, was associated with a 16% lower breast cancer risk, though the replacement of red meats altogether was not associated with lowering postmenopausal breast cancer risk. The results indicate that in general, breast cancer risk can be reduced if consumers substituted one serving of red meats with a serving of poultry. Though poultry is found to be associated with the reduction of breast cancer risk, excluding all red meats from the diet is not found to reduce the risk of breast cancer. This means that red meats are not the only factor that influences breast cancer risk. Diet is vital component to life and it has the ability to influence the progression of diseases.
Plant-based Protein Intake and Breast Cancer Risk:
Everyone has different dietary preferences and animal meats are not the exclusive source of protein. Adequate protein intake can be acquired through plant-based sources such as soy-based products, legumes, nuts and seeds. Researchers questioned whether the plant-based protein sources would affect the risk of breast cancer similarly to the animal-based protein sources. Research was conducted to explore the effect of plant-based protein intake and the correlation to breast cancer risk.
Soy foods contain isoflavones, which are phytoestrogens that have anti-carcinogenic properties. The evaluation of adolescent soy food intake and breast cancer risk was completed by Lee and co-researchers to explore the correlation between the two components. The FFQ results were obtained from 73,225 Chinese women from the Shanghai Women’s Health Study. The FFQ incorporated different types of soy based foods such as soy milk, tofu, soybeans (dried or fresh), soybean sprouts, and other soy products. During interviews throughout the twelve months of the study, participants indicated the duration and amount of soy foods consumed during adulthood as comparison to adolescence intake. The follow-up time of the study was 7.4 years after the preliminary questionnaire and 594 cases of breast cancer was identified. High soy intake during adolescence indicated a 43% reduced risk of premenopausal breast cancer disease (relative risk: 0.57; 95% CI: 0.34, 0.97). The results indicate that groups of people who consume large amounts of soy foods during adolescence significantly reduce their risk of breast cancer. The study implies that soy-based foods are good sources of protein to consume during adolescence in order to reduce breast cancer risk.
Soy foods are a plant-based type of protein; the soy foods indicate a breast cancer risk reduction, but researchers questioned if this was true for all plant-based protein sources. In a population based case-control study, women ages 25-74 who were first diagnosed with breast cancer between June 2002 and April 2003 were identified using the Ontario Cancer Registry. A 55-item food frequency questionnaire regarding diet between the ages of ten and fifteen from 2,865 participants with breast cancer and 3,299 control participants was evaluated. The results showed that a diet higher vegetable protein intake during adolescence is inversely associated with the risk of breast cancer (odds ratioQ5-Q1= 0.80; 95% CI=0.68 to 0.95; Ptrend=0.01). The study showed that increased intake of vegetable proteins during adolescence is associated with a decreased risk of breast cancer. In general, both studies examining the effects of plant-based protein intake during adolescence and breast cancer risk found that adolescent diet higher in plant-based protein foods leads to lower breast cancer risk.
Grain and Fiber Intake and Breast Cancer Risk:
Carbohydrate is one of the macronutrients that are important fuels for the human body. Grains are one of the main sources of carbohydrates consumed. Fiber is an important part of the diet, which can be found in foods such as whole grain foods, fruits and vegetables. Eating healthy grains and fiber is known for positive health effects and studies are exploring the correlation between adolescence grain and fiber intake and the risk of breast cancer.
In another study done by Farvis, an evaluation of diet and breast cancer risk using the NHSII to examine the correlation of adolescence grain and fiber intake and the risk of breast cancer. The baseline report of the FFQ was completed in 1991, where the participants recalled their diets from adolescence. A follow up questionnaire was completed every four years after the preliminary survey. Whole grain and refined grain foods intake during adolescence were not associated with the risk of breast cancer. The results also showed that there was no statistically significant association with adolescent intake of white bread, dark bread, or rice intake and the risk of breast cancer. Although whole and refined grains did not show an association with breast cancer risk, adolescent intake of cold breakfast cereal was inversely associated with the risk of postmenopausal breast cancer (for each 2 servings/week: RR 0.93; 95 % CI 0.87–0.99). The results indicate that the risk of breast cancer is not associated with intake of whole and refined grains, but there is an association between cold cereal and breast cancer risk. This indicated that there may be components within cold cereal that decreases the risk of breast cancer that whole and refined grains do not offer. Further testing would need to occur in order to explore the association between cold cereal and breast cancer risk.
A diet high in fiber is hypothesized to inhibit the reabsorption of estrogen, leading to a decrease level of estrogen circulation. Estrogen is an important factor that influences breast tissue growth, thus the decreased level of estrogen induced by high fiber intake is expected to lower the risk of breast cancer disease. Similar to the other studies, the study examining adolescence fiber intake and breast cancer risk is based on the Nurses’ Health Study II. A total of 44,263 women were available to take part in the fiber intake during adolescence analysis. The study showed that there was a statistically significant association between total dietary fiber intake and lower breast cancer risk. The two types of fiber, soluble and insoluble, were both explored and showed that there was an association with lowering breast cancer risk. Total dietary fiber intake during adolescence is associated with a lower breast cancer risk (relative risks for highest versus lowest quintile 0.84; 95% CI 0.70–1.01; Ptrend = .04). In general, the increased fiber intake decreases the risk of breast cancer. This indicates that both soluble and insoluble fiber intake during adolescence can reduce the risk of breast cancer during adulthood.
Conclusion:
Overall, the area of research between the correlation of diet and breast cancer risk is still very new. Based on the studies examined, it can be seen that different foods have different effects on breast cancer risk. High intake in red meat during adolescence is associated with increased breast cancer risk, whereas high intake of poultry, soy proteins and vegetable proteins are associated with a decreased breast cancer risk. Whole grain food intake did not show an association with lower premenopausal breast cancer risk, but fiber, a component found in who grains shows that an adolescent diet high in fiber intake is associated with a decrease risk of breast cancer. The growth and development of the body is influenced by diet and lifestyle. It can be seen through the different studies that diet during adolescence can influence the progression of diseases in adulthood such as breast cancer.
Another limitation of the studies done is that all of the studies depended on food-frequency questionnaires regarding diet in the past. Food-frequency questionnaires depend on the participants to recall their diet from the past. It may be difficult for some people to recall their diet within the last week, so it is expected that recalling diet from at least ten years before would be very difficult and somewhat inaccurate. One way to gather more accurate data would be to follow adolescents and their diet until adulthood to examine the association between adolescence diet and the risk of breast cancer.
Diet is a major factor of growth and development. The intake of different foods can increase the progression of diseases while others can reduce the risk of diseases. Breast cancer is the most common form of cancer development in women, but men can be diagnosed with breast cancer as well. The studies are significant because it allows people to obtain knowledge about the importance about diet and disease prevention.