Last month, a study published in the medical journal The BMJ (a weekly peer-reviewed medical journal published by the British Medical Association) connected the consumption of ultraprocessed foods to a higher risk for colorectal cancer. Dr. Fang Fang Zhang, a researcher at the Tufts University Friedman School of Nutrition Science and Policy, led this project, focusing specifically on the effects of ultraprocessed diets on cancer risk through a large cohort study over 28 years.
A key finding in her study was that when comparing the highest and lowest quintile of men based on ultraprocessed food consumption, those who had consumed more processed foods had a 29% higher risk of developing colorectal cancer. Notably, her study did not have the same findings for women. Zhang mentions this is likely due to women consuming more processed dairy products, which have some nutritional health benefits. In comparison, men were more likely to consume ultraprocessed foods with very little nutritional value.
Colorectal cancer refers to both colon or rectal cancer, depending on where the cancer first starts. It is the third most commonly diagnosed cancer in the country, with colon and rectal cancers having an average of 64% and 67% 5 year relative survival rates, respectively. According to the American Cancer Society, there will be more than 100,000 new cases of colon cancer in the United States this year. Common treatments for colorectal cancer are currently surgery and chemotherapy, which both have the potential for long-term negative health impacts on the patient.
Given the severity of this disease, studies such as Dr. Zhang’s that look at how our everyday diets can affect our chances of developing colorectal cancer are extraordinarily valuable. While at Tufts, Zhang has worked on several projects looking at the link between nutrition and cancer risk, conducting large population-based studies in the field of nutritional epidemiology. She has also led a population-based project focusing on national-level prevention of cancer through nutritional policies and interventions. We recently had a chance to interview Dr. Zhang on her research.
SAMPAN: How did you get involved with research, specifically in the field of nutritional epidemiology?
ZHANG: Nutrition is in our daily lives, right? We eat foods every day and what we eat plays an important role in many outcomes – disease outcomes especially. So for me, I think it is good for me to find out what are the dietary risk factors that could contribute to the risk for various diseases. Then we can potentially intervene – hopefully to change… what we eat [and] the food environment… [helping to] reduce these dietary diseases.
Zhang also mentions how dependent the United States population is on ultraprocessed foods, which is a majority of many people’s daily caloric intake. She specifically touches on the nutritional deficiencies of ultraprocessed foods as well.
ZHANG: Ultraprocessed foods does offer much convenience to life and also does help to extend the shelf life of foods.… [Food processing has also] helped improve the availability of foods.… The problem is that we rely too much on these foods. We did a study a while ago trying to look at the trends in the consumption of ultraprocessed foods in US children, and ⅔ of our children’s daily calories come from ultraprocessed foods. In adult populations, it is about 57 to 58 percent.… More and more studies have reported adverse health outcomes such as obesity, hypertension, and cardiovascular diseases.… Overall, ultraprocessed foods do have some nutrition issues.… [Ultraprocessed foods are] overall low in dietary fiber,… high in added sugars, high in sodium,… and higher in fats as well.
SAMPAN: With processed foods being so accessible and given that not all processed foods would equally impact health, what are some healthier processed food options that people can find?
ZHANG: How ultraprocessed foods are determined is based on food processing, not necessarily based on nutrients. Some ultraprocessed foods could be healthier in its nutrient content, even if it is ultraprocessed. An example would be whole grain foods. Whole grain foods could be ultraprocessed, but whole grain foods could contain a higher level of fiber, which is a healthy nutrient.… [But] even though whole grain foods are higher in dietary fiber, we can add added sugars to it.… Whole grain foods do not necessarily mean they are healthy foods.… I would say the healthy version of ultraprocessed whole grain foods… [have] little or no added sugars, so that could be a healthy option.
SAMPAN: Ultraprocessed foods are much cheaper and more available to people than fresh produce. How may this impact people of a lower socioeconomic status?
ZHANG: This is a problem, I think. We are also looking into some of the dietary nutrition policies for disease prevention here at Friedman School at Tufts. I am one of the faculty members who work to help evaluate [what] nutrition policies we can develop [as well as their] cost-effectiveness,… what are the expected benefits, and what is the number of cancer cases being reduced.… We are thinking about how to improve nutrition at the population level. Food price is one strategy… so we need to think about whether we can have some subsidy policies, providing fresh vegetables and fruits – those unprocessed or minimally processed foods – at a cheaper price, especially for those with a low level of income.… Thinking about how we can help improve the diet in the population, especially the underserved population, where they do have a higher risk of cancer, cardiovascular disease, and an overall poorer diet.
When asked about what research still needs to be done in this field, Zhang said, “We need more studies like this one… you have to study a lot of people and follow them for a long time.” She expressed a need for more observational studies, specifically ones studying differences in health outcomes for different population subgroups, as well as studies exploring the mechanism behind the link between colorectal cancer and ultraprocessed foods. It is her hope that greater scientific evidence supporting this connection can help inform public policy and nutritional education in the future.
As for what Sampan readers can do to help improve their diets, Zhang recommends cooking with “fresh vegetables and fruits,… fresh meat, poultry, seafood.… Dairy foods can also be a good option if they do not have a lot of added sugar.” As for what to avoid in the grocery store, Zhang emphasizes “packaged foods,… sugary beverages,… industrial bread, and snacks!… A lot of them are ultraprocessed.”
