In 2017-2018, the National Health and Nutrition Examination Survey (NHANES) reported that 42.4% of adults in the U.S. are considered obesity. Within the first year of the pandemic, prevalence increased by three percent meaning nearly 2 in 4 adults had obesity [1]. CDC predicts that by 2030 about half of US adults will be obese.

Research has shown that individuals who are overweight or obese have an increased risk of cardiovascular disease, diabetes and the most daunting of all- cancer. According to the American Institute for Cancer Research, one out of three cancers is caused by excessive body fatness and is completely preventable [2].

These cancers make up forty percent of all cancers diagnosed in the US each year and may be linked to factors such as excess body fat, inflammation in the body, increased levels of insulin and estrogen imbalance [3].

Overview

Obesity is defined as the excessive or abnormal accumulation of fat in the body that influences health through ongoing low grade inflammation and abnormal hormonal signaling [4,5].

There are 2 types of adipose tissue:

White adipose tissue is located in specific stores throughout the body and serves as an energy reserve by providing fatty acids to other tissues via lipolysis or the process of breaking down lipids [6].

Brown adipose tissue transfers energy from food to heat. The production of heat from brown adipose tissue is activated when the organism is in need of extra heat, however this production and the decrease in metabolic efficiency can be significant [7].

Inflammation

The low grade inflammation caused by excess white adiposity can result in cancer development. White adipose cells ( containing stored fat ) secrete cytokines (signaling proteins) that stimulate and promote the growth of abnormal cells [8,9].

Whole, unprocessed foods are known to be anti-inflammatory, or with very low inflammatory index, such as fruits and vegetables, whole grains, legumes, nuts, fish, white meats, and olive oil and seem to be the best way to decrease overall body inflammation [10].

Insulin and Insulin-like Growth Factor-1

Being overweight or obese is associated with insulin resistance, a condition in which insulin cannot regulate blood sugar levels due to large amounts of glucose (sugar) in the blood for an extended period of time.

Insulin resistance may lead to dyslipidemia (abnormally elevated cholesterol in the blood), hyperglycemia (excess of glucose in bloodstream), hypertension which are all major characteristics of obesity. High levels of glucose in the blood has oncogenic potential [11,12].

Insulin increases the bioactivity of insulin-like growth factor-1 (IGF-1), a molecule that is proven to increase cancer risk, especially breast and prostate cancers, but possibly many other types [12]. High levels of insulin and IGF-1 present in our blood promotes growth and reproduction of cancer cells.

Estrogen

Estrogen is considered to play an important role in promoting the proliferation or growth of both normal and cancerous breast cells [13]. This hormone is involved in a number of physiological processes including regulating energy balance, stress responses, mineral balance, as well as sexual development. 

In premenopausal women, estrogens are mainly produced by the ovary but in postmenopausal women, fat tissue is the main site of estrogen production[14]. Higher levels of estrogen in the postmenopausal period can promote the development of endometrial cancer and breast cancer [15].

Amy Bragagnini, oncology nutrition specialist and a spokesperson for the Academy of Nutrition and Dietetics recommends some dietary changes for menopausal women as a plant-based diet rich in fiber lowers levels of estradiol, or estrogen produced in the ovaries [16,17].

Isoflavones mimic estrogen which allows them to maintain hormone balance. Isoflavones bind to estrogen receptors, thus not allowing estrogen to bind, which does prevents cancer cell growth. [18]. They are found in soy, soy products, and other legumes [16].

They also have non-hormonal properties ultimately reducing the risk of breast cancer [18].

Preventative Dietary and Lifestyle Modifications

The Western Diet or the so called The Standard American Diet consists of processed foods, red meat and large amounts of simple, refined carbohydrates. This eating pattern is highly inflammatory. Simple carbohydrates such as pasta, pizza, white rice and bread should be eaten in moderation or better yet avoided as these refined grains that have had their bran, fiber, and nutrients removed[19].

1. Decrease overall body inflammation by reducing processed foods

Consume only whole foods and avoid all processed foods. Minimize all foods that come in a bag, box or any type of packaging. Shop only from the periphery sections in the grocery store where the fresh produce is.

2. Choose you fats wisely

Avoid all hydrogenated fats found in commercial food products such as chips, cookies, candies, pastries, crackers and seed oils. Seemingly healthy products such as skinny popcorn also contain unhealthy fats that lead to inflammation.

Oils such as corn, soybean and heat derived seed oils are inflammatory and cold pressed oils such as olive oil are anti- inflammatory.

3. Increase the intake of diary fiber

Viscous dietary fiber from oats, brawn rice, beans, lentils slows glucose absorption, reducing insulin section and hyperinsulinemia ( high levels of insulin which is associated with inflammation ). Fiber also may decrease circulating estrogen levels due to decreased reabsorption from the GI tract.

The intestinal microbiota act on fermentable fiber and resistant starch and promote the production of butyrate and short- chain fatty acid ( SCFA ). Buturate and SCFA reduce colonic inflammation and provide support to normal colon cell this protect us from colon cancer.

5. Increase antioxidant intake

Dietary carotenoids, vitamins C and E ( not from supplement sources ) provide direct DNA protective effect by quenching free radicals thus stopping cancer formation in its initial stages. Carotenoids show potential to promote apoptosis ( cancer cell death ).

6. Reduce the intake of red meat and processed meat

The World Cancer Research Fund and The American Institute for Cancer Research (WCRF / AICR) recommend limiting red meat consumption to no more than 12 oz per week and avoiding processed meats. The risk for developing colorectal cancer increased by 12 % for every 100 gm red meat consumed daily and by 16 % for every 50 gm of processed meat consumed daily. [20]

7. Reduce the consumption of alcoholic beverages

The WCRF / AICR recommends limiting the consumption of alcoholic beverages for these who drink to not more than one standard drink for a women and two standard drinks for a men.

• Ethanol is known as humans carcinogen as it breaks down to acetyl aldehyde, a substance that directly starts the cancer processed on cellular level.
• Ethanol acts as solvent enhancing the penetration of dietary carcinogens into the cell.
• Alcohol increases the circulating estrogen which is know risk factor for breast cancer.

8. Be careful with dietary supplements

Some dietary supplements can be protective against cancer while others can increase one’s risk for developing cancer. One needs to discuss the intake of dietary supplements with a health professional before taking them.

• Calcium supplements dosed no more than 200 mg per day can be protective against colorectal cancer, however dietary calcium intake needs to be considered. [22]
• Diets high in calcium including from supplements can increase risk for prostate cancer, especially for these who have other risk factors. [23]
• Dietary supplements associated with increased overall cancer risk include B-carotenoids and vitamin E. Based on the results of six randomized controlled trails smokers who take high dose B-carotenoids have increased risk for lung cancer.
• Vitamin E supplements may increase risk for prostate cancer.
• Vitamin D supplements likely reduce risk for colorectal cancer.

9. Eating Predominant a Plant-Based Diet

Plant-based eating avoids animal products, reduces fat intake, and adds a serving of soy products. As a result, these dietary changes may improve hormone fluctuations, cholesterol levels, sleep and bone health [16]. Increasing intake of whole soy foods and fermented soy products while limiting processed foods, alcohol, caffeine and sugar may decrease estrogen levels and cancer risk [16].

Intermittent fasting or periods of eating combined with periods of fasting is associated with lower levels of insulin, or the fat-storing hormone. During fasting, insulin levels decrease allowing our bodies to use our fat stores for energy thus resulting in weight loss [20].

10. Be Physically Active

Moving our bodies can be crucial in reducing weight gain, improving insulin sensitivity (reducing insulin levels), and improving immune function [15]. This combination of diet and exercise can help us improve our health and ultimately prevent the development of cancer.

All forms of physical activity including recreational and occupational protect against cancer of the colon and the breast.

Vigorous physical activity is know to protect agains the cancer of breast in premenopausal women and protect against prostate cancer recurrence. Physical activity is known to decreased inflammation and reduce body weight thus lower the risk of all types of cancer.

Aim for 150 min of moderate physical activity per week or 30 min daily or 60 min of vigorous activity per week. As your fitness and endurance improved increase to 30 min of virtuous activity daily.

Citations

1. https://www.ers.usda.gov/amber-waves/2022/july/adult-obesity-prevalence-increased-during-the-first-year-of-the-covid-19-pandemic/
2. https://www.aicr.org/
3. https://www.cdc.gov/cancer/obesity/index.htm
4. Panuganti KK, Nguyen M, Kshirsagar RK. Obesity. 2022 Aug 8. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan–. PMID: 29083734.
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6. Qian X, Meng X, Zhang S, Zeng W. Neuroimmune regulation of white adipose tissues. FEBS J. 2022 Dec;289(24):7830-7853. doi: 10.1111/febs.16213. Epub 2021 Oct 4. PMID: 34564950.
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8. https://www.cancer.gov/news-events/cancer-currents-blog/2022/reducing-inflammation-to-treat-cancer
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16. https://www.healthline.com/health-news/menopause-low-fat-plant-based-diet-may-reduce-hot-flashes-promote-weight-loss#Dietary-changes-and-menopause:-What-experts-think
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21. https://medicalnutritionaltherapy.com/2023/01/01/benefits-of-fasting/
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