Excess body weight is responsible for about 11% of cancers in women and 5% of men. Did you know that the risk for postmenopausal breast cancer is 1.5 times higher in overweight women and 2 times higher in women with obesity? Let’s understand more about how obesity contributes to breast cancer risk.
How Does Body Weight Affect Breast Cancer Risk?
Being overweight or obese increases the risk for breast cancer, especially in postmenopausal women. Your Body Mass Index (BMI) determines if you have a healthy weight, are overweight, or are obese.
A BMI between 18 and 24.9 is considered healthy. A BMI between 25 and 29.9 means that you are overweight. If your BMI is higher than 30, it could indicate obesity.
Women with a BMI over 25 are at an increased risk of developing breast cancer than those with a healthy weight. In addition, this risk is exceptionally high after menopause. Being overweight or obese also increases the risk of breast cancer recurrence.
The exact link between increased weight and breast cancer risk is complicated and multifactorial. The high risk appears to be connected to the estrogen production by the fat cells.
In premenopausal women, estrogen is mainly produced by the ovaries. However, in postmenopausal women, adipose tissues or fat tissues is the main source of estrogen production.
The number of fat cells is higher in overweight or obese women. This results in increased estrogen production, which is a risk factor for breast cancer development. This is especially of significance for Hormone-Receptive breast cancers that develop and grow on exposure to estrogen.
It has been found that women who are obese after menopause are at a 30% higher risk of developing breast cancer. Gaining more than 22 pounds after menopause can increase the risk of breast cancer by 18%.
Obesity And Breast Cancer Risk
Obesity and Breast Cancer Risk in Premenopausal Women
Studies report an association between obesity and a lower risk of Estrogen-Receptor Positive (ER-Positive) breast cancer but a higher risk of ER-negative and Triple-negative breast cancer in premenopausal obese women.
In addition, a study from the Breast Cancer Surveillance Consortium database showed that obesity is associated with an increased risk for Inflammatory Breast Cancer (IBC) in premenopausal women.
Obesity and Breast Cancer Risk in Postmenopausal Women
The Million Women Study followed 1.2 million UK women ages 50 to 64 years for a mean of 5.4 years. Out of these, 45,037 women had breast cancer. The study identified a nearly 30% higher risk of developing postmenopausal breast cancer with obesity.
A meta-analysis of 34 studies reported that the risk of postmenopausal breast cancer increases with every 5kg/m2 increase in BMI.
Risk Of Breast Cancer Mortality In Obese Patients
Obesity affects the prognosis and survival rate of breast cancer patients. A recent study found that obese women with breast cancer experienced an 11% decrease in overall survival rate, irrespective of their menopausal status.
Besides breast cancer, obesity is a risk factor for type 2 diabetes and heart diseases - the latter seems to be the leading cause of mortality in women with early-stage breast cancer.
It has also been observed that obese women with breast cancer are more likely to experience complications during surgery and radiation.
In addition, systemic chemotherapy and endocrine therapy for treating breast cancer are less effective in obese women, further reducing prognosis and survival rate.
Breast cancer-specific mortality among obese women is 1.3 times higher compared to women with a normal BMI.
The mortality rate in obese women is also dependent upon the type and characteristics of the tumor. For example, obese women with Luminal A and Luminal B breast cancer were 1.8 and 2.2 times more likely to die from cancer than normal-weight women.
However, obesity was not associated with breast cancer-specific mortality among women with HER2- and triple-negative tumors.
Genetic Factors That Influence The Relationship Between Obesity And Breast Cancer Risk
The BRIP1 Gene
BRCA1 Interacting Helicase 1 (BRIP1) is located on chromosome 17 and, along with the BRCA1 gene, helps repair any damage to the DNA. It is also responsible for maintaining chromosomal stability.
rs16945628 is a Single Nucleotide Polymorphism (SNP) in the BRIP1 gene. The TT genotype of this SNP is associated with an increased risk of breast cancer in women with a BMI of ≧25 kg/m2.
The IGFBP3 Gene
Insulin-like Growth Factor Binding Protein 3 or IGFBP3 gene is located on chromosome 7 and participates in cell growth, multiplication, and differentiation, and cancer development in the breast tissue.
rs2854744 is an SNP in the IGFBP3 gene linked to the risk of breast cancer. The CC genotype of this gene significantly increases the risk of breast cancer compared to the AA genotype. This increase was found to be more pronounced in older women.
Studies also showed that women carrying the AC+CC genotypes of the IGFBP3 gene had a larger tumor size in the breast.
Non-Genetic Factors That Influence The Relationship Between Obesity And Breast Cancer Risk
Obesity is a critical non-genetic risk factor for breast cancer.
- Studies show that women who gained weight as adults have a greater risk of developing breast cancer than those who were overweight since childhood.
- Having excess fat around the waist area may increase breast cancer risk more than having extra fat in the hips and thighs in women.
Other factors that increase breast cancer risk in obese women are:
- Lack of physical activity
- Taking hormones like oral contraceptives or Hormone Replacement Therapy (HRT) during menopause
- Reproductive history: Women who have given birth after 30 years of age, have not had a full-term pregnancy, and have not breastfed have an increased risk of breast cancer.
- Drinking alcohol and smoking
Does Weight Loss Reduce Breast Cancer Risk?
According to a 2019 study, sustained weight loss is associated with lower breast cancer risk for women aged 50 years and older.
The researchers looked at 180,885 women from 10 studies. The women's weights were recorded 3 times over a period of 10 years; once when they enrolled and once every 5 years.
Weight changes of 2 kilograms or less (about 4.4 lbs) were counted as stable.
The study reported the following*:
- Women who lost 2 to 4.5 kg (about 4.4 to 10 lbs.) had a 13% lower risk.
- Women who lost 4.5 to 9 kg (10- 20 lbs.) had a 16% lower risk.
- Women who lost 9 kg or more (20+ lbs.) had a 26% lower risk.
- Women who lost 9 kg or more and gained some (but not all) of the weight back had a lower risk.
*Compared with those whose weight was stable.
The study did not include women on postmenopausal hormone therapy, and the results were more prominent in obese or overweight women.
Despite this, the study suggests that even a modest amount of sustained weight loss can lower your breast cancer risk and improve survival rate, if diagnosed with breast cancer.
Recommendations to Reduce Breast Cancer Risk
- Maintain a healthy weight by eating a balanced diet, cutting out excess carbohydrates and processed foods, exercising regularly, and avoiding alcohol.
- Have a healthy eating pattern that is rich in fiber, proteins, vitamins, and minerals.
- If you have been advised to take hormone replacement therapy and oral contraceptives, discuss with your doctor the risk involved.
- Breastfeeding can lower breast cancer risk, especially if a woman breastfeeds for longer than one year.
- If you have a family history of breast cancer, genetic testing is recommended to detect abnormal changes in the BRCA1 and BRCA2 genes. Talk to your doctor to know more about this.
Summary
- Being overweight or obese increases the risk of developing breast cancer. This risk is exceptionally high in postmenopausal women.
- An increase in weight increases fat cells in the body and a subsequent rise in estrogen levels. Exposure to estrogen increases the risk of breast cancer development.
- Women with BMI over 25 have a higher risk for breast cancer.
- Obese premenopausal women have a lower risk for ER-Positive breast cancer but an increased risk for ER-negative and triple-negative breast cancer.
- Breast-cancer-specific mortality among obese women is 1.3 times higher than in women with normal BMI.
- Few genes like BRIP1 and IGFBP3 are associated with breast cancer risk in obese women.
- Other factors like lack of physical activity, hormone replacement therapy, reproductive history, alcohol consumption, and smoking increase breast cancer risk in obese women.
- According to a study, sustained weight loss in women over 50 can help reduce breast cancer risk compared with women whose weight was stable.
References:
- https://www.genecards.org/cgi-bin/carddisp.pl?gene=IGFBP3
- https://www.breastcancer.org/risk/factors/weight
- https://www.cancer.org/latest-news/how-your-weight-affects-your-risk-of-breast-cancer.html
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5591063/
- https://www.hindawi.com/journals/jo/2013/906495/
Abstract
Diet is as important to mental health as it is to physical health. Previous studies have reported that the "traditional" dietary pattern, loaded with vegetable oil, meat, salt, and organ meat, is associated with increased odds of anxiety and depression in women. A recent study by researchers at the Ruhr-University Bochum and University of Duisburg, Germany, has reported higher depression scores among vegetarians than non-vegetarians.
What is Depression?
Depression is a common yet serious mental condition that negatively impacts how you feel, the way you think and act. Depression occurs as a result of a combination of social, psychological, and biological factors.
Some of the common symptoms of depression are :
- Feeling of hopelessness
- Increased fatigue and sleep troubles
- Irritability (more often noted in men)
- Unexplained weight gain/loss
- Appetite changes
The Link between Depression and Diet
Depression susceptibility is related to diet both directly and indirectly. Unhealthy eating patterns can cause mood swings. When you stick to a healthy diet, you are setting yourself up for fewer mood fluctuations.
In particular, sugar is considered a major culprit. When consumed in higher quantities, it causes a temporary spike in 'feel-good' hormones like dopamine, which is not good for your health. In addition, the fleeting sugar rush followed by a crash is terrible for your mood.
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Link between Vegetarianism And Depression
A German research team conducted a meta-analysis on depression and vegetarian diet.
Meta-analysis refers to a procedure where the information collected from different experiments (with the same objective) is put together and studied. This combines the results of multiple studies to form a conclusion.
The analysis included data from 49,889 participants, of which 8,057 were vegetarians, and 41,832 were non-vegetarians. The large sample size makes this a robust study.
The researchers observed a higher depression score among vegetarians when compared to the non-vegetarians. But there was no causal relationship observed between them. That is, there was no proof that a vegetarian diet directly causes depressive moods. Depression didn't seem to increase a person's chance of adopting a vegetarian diet either.
This study, however, showed that it might be more likely that people switch to a vegetarian diet after developing mental health issues. The researchers cite three possible reasons for this:
- People with mental health issues may try to adopt a vegetarian diet to positively influence their minds.
- People with depression may develop more empathy towards animals’ sufferings, and this may cause them to avoid meat.
- People with mental health issues may generally be anxious about their health and switch to a vegetarian diet since it is perceived as a “healthy diet.”
Dietary Recommendations To Improve Your Mental Health
- Steer clear of processed snacks such chips as potato chips that can impair your ability to concentrate.
- Focus on eating plenty of fruits and vegetables along with foods rich in omega-3 fatty acids such as salmon
- Maintain a healthy weight and make sure to exercise daily.
Summary
- There is a complex relationship between our mental health and our dietary patterns.
- A recent study has found that vegetarians are more likely to be depressed than non-vegetarians.
- According to the study, vegetarians showed higher depression scores than nonvegetarians.
- It is not clear whether depressive moods lead to a higher probability of becoming a vegetarian or a vegetarian diet increases the risk of depression.
- Limiting the intake of processed snacks, including more fruits and vegetables in your diet, and maintaining a healthy weight with regular exercises are some ways to improve your mental wellbeing.
- According to the study, there was no proof that depression leads to vegetarianism and a vegetarian diet directly causes depression moods.
- People switch to a vegetarian diet after undergoing mental health issues.
References
- https://www.sciencedirect.com/science/article/abs/pii/S0165032721007771
- https://www.health.harvard.edu/mind-and-mood/food-and-mood-is-there-a-connection
A research study on the data from Adolescent Brain Cognitive Development (ABCD) Study suggests a relationship between certain regions in the brain and weight gain among children and adolescents. The study explored the relationship between “reward region” and food processing and suggests that this region may predict obesity in children.
Childhood obesity is a serious problem in the United States, putting children and adolescents at risk for poor health. Overweight children are much more likely to become overweight adults unless they adopt and maintain healthier patterns of eating and exercise.
Previous research has identified a region in the brain associated with overeating or unhealthy eating behavior.
The Reward System Region In The Brain
Almost all our actions are driven by two things: Necessity and Reward. An activity can be considered a reward when it motivates us or gives us pleasure. Neurons, the brain's fundamental working unit, communicates this "reward" using dopamine, which is popularly known as the "happy hormone."
Incidentally, food-reward is common in animal training routines. An animal is rewarded with a treat when it performs certain actions and this programming of food-reward is routinely used by animal trainers in zoos and entertainment venues and other animal training facilities.
Hedonic Hunger
Hedonic hunger describes eating for pleasure than hunger - to enjoy the taste rather than to meet the body's energy needs. This pleasure eating triggers the brain's reward system region, which can lead to overeating - a common cause of obesity.
The Study
"The ABCD study or the Adolescent Brain Cognitive Development Study is the largest long-term study of brain development and child health in the United States." The study was done on over 10,000 children from ages 9-10 and was followed up through early adulthood.
Using the data from this study, the researchers attempted to investigate the relationship between the reward system region in the brain (called the nucleus accumbens) and eating behavior by examining 5300 research participants.
It was observed that when 2000 participants returned for a one year follow up, the waist circumference had increased by an average of 2.76 centimeters per participant.
The cell density (number of cells for a given area) in the reward region of the brain was examined using a noninvasive MRI technique.
The MRI revealed changes in the cell density that reflected the increase observed in the waist circumference.
The study speculates that the increase in this cell density can be because of an inflammation caused due to a diet rich in high-fat foods.
The findings essentially tell us that a vicious cycle of pleasure eating leading to changes in brain, in turn leading to overeating and increasing the risk of obesity.
Not all children who carry a few extra pounds can be classified as obese. Weight fluctuations are commonly observed in the growing stage of children. Before you decide on dietary changes for your child based on any weight gain you see, it's best to consult a doctor. The doctor may use growth charts, calculate the BMI and, take a family history, and, if necessary, may order a few tests to outline the issue behind the weight gain.
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