“So to start, we know that an overall healthy dietary pattern has the potential to reduce cancer risk by 10% to 20%, which seems like a lot to me.”
These were the opening words of Gabrielle Emanuel, WBUR Senior Reporter and moderator of the Harvard T.H. Chan School of Public Health’s discussion “Reducing Cancer Risk Through Nutrition.”
Ms. Emmanuel addressed three members of the panel, Edward Giovannucci: Professor of Nutrition and Epidemiology and Timothy Rebbeck: Vincent L. Gregory, Jr. Professor of Cancer Prevention, TH Chan and Eliza Leone: Registered Dietitian and instructor of the Harvard Culinary Medicine and Nutrition Course.
While protein, fats and carbohydrates were examined, the focus was on lean meat, plant-based protein, vegetable oils and whole grains. But amidst the feeding maze, causality remains unclear, and hand waving is more common than tangible results.
Here are the highlights
What does a healthy diet consist of?
- Protein: Prioritize lean meats and plant-based protein sources like beans and lentils.
- Fats: Emphasize plant-based fats like nuts, avocado, olive oil and minimize animal-based fats.
- Carbohydrates: Choose whole grains, vegetables and fruits instead of processed carbohydrates.
What is the connection between nutrition and cancer?
Most studies on disease and nutrition have focused around diabetes and cardiovascular disease; Less has been done in the field of cancer. However, two important risk factors mentioned by the panelists were associated with all three diseases.
“Inflammation is not cancer, but it can set the stage for cancer to emerge.”
–Dr. Timothy Rebbeck, Professor of Cancer Prevention
chronic inflammation A prolonged and dysregulated immune response is known to play an important role in both the initiation and progression of cancer. By creating a microenvironment that supports the survival and proliferation of cancer cells that release reactive oxygen and nitrogen species that can damage DNA and promote genetic mutations. Dr. As an example, Giovannucci cited the important relationship between hepatitis, chronic liver inflammation, and subsequent liver cancer. Inflammation in the diet is milder and affects the entire body.
“Just by dividing so many cells, your chance of getting a mutation that will eventually lead to cancer increases.”
-Dr.. Edward Giovannucci, Professor of Nutrition and Epidemiology
Obesity It is a significant risk factor for cancer and has obvious links to our dietary intake. More specifically, obesity is often accompanied by insulin resistance, leading to elevated levels of insulin and insulin-like growth factor-1 (IGF-1), which promote the growth of cancer cells. Additionally, obesity is associated with increased estrogen production in postmenopausal women, and high estrogen levels are linked to certain types of cancer, including breast and endometrial cancer. Finally, adipose tissue biologically actively produces and secretes pro-inflammatory molecules such as tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and adipokines such as leptin. These substances act as signaling molecules that trigger and sustain inflammation within and beyond fatty tissue.
Unhealthy eating habits have an effect through these two mechanisms.
What are the functions of Vitamins and Supplements?
Vitamins and supplements, touted by many as potential saviors, offer mixed results. There is no magic bullet among vitamins and caution is advised against relying solely on supplements.
“There have been some long-term trials [of vitamins], randomized trials and do not show any harm. After about 10 years of use you should start to see at least some benefit. So there is some evidence of long-term use. … But I think that’s probably enough evidence to say it doesn’t hurt and it might help.”
– Edward Giovannucci: Professor of Nutrition and Epidemiology
Two compounds that may provide some protection are Vitamin D, where a Harvard study showed a reduction in cancer deaths but no change in incidence, and calcium, which appears to play a protective role in colon cancer. Ms. Leone continued by pointing out that there is no ‘magic bullet’ among vitamins and nutritional supplements:
“Our bodies can absorb these nutrients more easily through food than through supplements. So when we take any supplements – nutritional supplements – they are to help fill in the gaps of what we are missing.
What is the role of alcohol?
“I wanted to say, [alcohol] Because breast cancer is affected by alcohol, it probably slightly increases your risk of cancer, especially in women. “But there may potentially be some benefits on diabetes and cardiovascular disease.”
Alcohol is a carcinogen and cancers have been linked to “high patterns of alcohol consumption.” People find this particular message difficult because it interferes with their lifestyle. But just as driving is a risk that can be reduced with a seat belt, “you can also make smart choices or limited choices about alcohol consumption.” For those who did not abstain, the panel followed the general U.S. recommendation: one glass a day for women, two for men.
Does exercise affect our cancer risk?
Exercise has emerged as a potential counterbalance to a suboptimal diet. While it’s not a carte blanche to indulge in unhealthy eating habits, exercise can offset some of the negative effects, highlighting the importance of energy balance.
“So I think exercise can kind of offset some of the potential bad effects of a poor diet. Now I’m not saying have a bad diet and exercise. But the other way to think about it is that the worst thing you can do is not exercise and eat poorly. So do at least one of both.” “It’s better to do it at the same time. … I think it’s about energy balance.”
– Edward Giovannucci: Professor of Nutrition and Epidemiology
Are there any myths you would like to see debunked?
Dr. Rebbeck talked about the belief that eating refined sugar feeds cancers. He noted that dysfunction of the mTOR metabolic pathway in cancers is driven by glucose in cells. However, it is wrong to interpret this as eating refined sugar feeds the tumor.
Ms. Leone pointed out that there is a lack of significant evidence to support the role of intermittent fasting in preventing cancer.
Do you have any practical advice on using your diet to reduce cancer risk?
– Learn to cook simple, nutritious meals at home to control ingredients and portion sizes. Take advantage of the calorie density, eat foods that have fewer calories, are larger in volume and therefore more filling
Prioritize plant-focused diets to emphasize increased intake of plant-based foods, including a variety of fruits, vegetables, and whole grains, but do not exclude animal products entirely.
– Make gradual, achievable and sustainable changes in eating habits and lifestyle to reduce the risk of cancer.
Fun Fact: Dr. Rebbeck noted that he and his wife used smaller plates to make their portions appear larger and possibly more filling; Small plates and small glasses to benefit from the psychological effect of small plates making the portion appear larger. Dr. from Cornell This work by Brian Wansink was questioned and Dr. 15 of Wansink’s articles along this psychological line were retracted.
The only constant in the complex dance between diet and cancer seems to be the lack of clear answers. The journey through this nutritional maze requires a nuanced understanding that emphasizes moderation, whole foods, and a mindful approach to lifestyle choices.
Here’s a summary of the evidence on nutrition and cancer. Watch video of the discussion here. And you may find this article of more than passing interest. Is everything we eat linked to cancer? A systematic cookbook review American Journal of Clinical Nutrition