Dietary changes represent ‘growing priority’ for GI symptom relief, cancer prevention
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We have long known that our diets affect our health, but many questions remain about diet’s impact on conditions like cancer and its potential value in treating a wide variety of health conditions.
Two studies presented recently at Digestive Disease Week 2022 shed further light on these connections. Although they examine two different conditions — irritable bowel syndrome and colorectal cancer precursors — both tell us more about the impact of diet on health and particularly our gut health.
Ultra-processed foods and cancer risk
Growing evidence indicates that a diet high in ultra-processed foods can be detrimental to health. These foods include salty or sugary snacks; refined carbohydrates, such as white breads and pasta; sugar-sweetened beverages; cheeses; and processed meats. We know that eating too much of them can lead to weight gain, heart disease and diabetes, but a recent study suggests a concerning link between consuming these foods and developing polyps in the colon, which are precursors of CRC.
In their study, Mingyang Song, MBBS, ScD, of the Harvard T.H. Chan School of Public Health, and colleagues found a link between ultra-processed foods and polyps that form in the colon and can become cancerous if not removed. Using data from the Nurses’ Health Study (NHS), NHS II and the Health Professionals Follow-up Study, the researchers analyzed records of more than 144,000 patients who had undergone at least one colon screening, such as a colonoscopy, and were followed for 18 to 20 years until diagnosed with colon polyps.
They also assessed patients’ diets by surveying them every 4 years to understand how regularly they consumed ultra-processed foods. Those who ate the largest amount of these foods had a greater risk of polyps. Processed meats had the strongest association with higher-risk polyps. Song and colleagues concluded that higher consumption of ultra-processed foods can lead to an increased risk for developing polyps — suggesting that this may be a modifiable dietary target for early prevention of CRC.
Exactly how ultra-processed foods might lead to colon polyps is still unclear. One theory suggests that poor diet and increased consumption of these foods could alter the ways that microbes in our gut obtain the nutrients they need or the way that microbes are structured within the gut. This may shift our gut microbiome so that it generates higher levels of harmful metabolites that could promote the development of polyps or even cancer.
Diet as treatment
While our diets can contribute to negative health effects, they can also improve our health, and scientists are exploring ways that diet can actually help treat certain digestive conditions.
Another recent study shows how diet can help alleviate symptoms for patients with IBS. Sanna Nybacka, RD, PhD, of the department of molecular and clinical medicine at the University of Gothenburg in Sweden, and colleagues conducted a randomized, controlled clinical trial to compare the effects of two diets and medical treatment on IBS symptoms. Nearly 300 adults with IBS were split into three groups: One group was assigned to receive IBS medication, the second to eat a low-carbohydrate diet and the third to eat a diet low in sugars that may cause gastrointestinal distress [(fermentable oligo-, di- and monosaccharides and polyols (FODMAP)].
After 4 weeks, IBS symptoms had improved for all three groups, but the two dietary groups experienced greater improvement than those who received medical treatment. More than 70% of those in the dietary groups had a significant reduction in symptoms, and nearly 50% reduced their symptoms by half. The researchers concluded that these results suggest dietary changes may be considered as a first-line treatment for IBS.
Our understanding of diet-based approaches for treating patients with IBS continues to evolve, and it is a growing priority to use dietary changes for IBS symptom relief. But since many medications are available for IBS, dietary approaches may still be somewhat underutilized. However, it is important to note that these options are not mutually exclusive. Personalized, effective treatments for IBS may involve diet-based strategies as well as medications.
Together, these two new studies add to our growing understanding that long-term dietary patterns — and even short-term dietary changes — may have a substantial impact on GI health, function and symptoms. At your next visit, talk with your patient about dietary changes that may be helpful for them and their gut health.
For more information:
Andrea Shin, MD, MS, is an assistant professor of medicine and the Philip J. Snodgrass Scholar in Gastroenterology and Liver Disorders at Indiana University School of Medicine.
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