Over the past 20 years, there has been an increase in colorectal cancer (CRC) incidence in individuals younger than 50 years old in 9 countries including the United States, although CRC incidence has decreased or remained the same in older adults [Siegel et al., 2017 as cited in reference i]. In older adults, increased risk of CRC has been linked to poor diet quality [Randi et al., 2010, Fung et al., 2003, Magalhaes et al., 2012, and Wu et al., 2004 as cited in reference i]. This may be due to hyperinsulinemia, chronic inflammation, and gut dysbiosis [Chan et al., 2010, Song et al., 2015, Feng et al., 2015, Louis et al., 2014, and O’Keefe, 2016 as cited in reference i]. In the below study, the authors explore the relationship between diet quality and early onset CRC [i].
Journal of National Cancer Institute
This prospective cohort study included over 29,000 women under age 50 from the Nurses’ Healthy Study II from 1991 to 2011. Participants completed self-administered questionnaires every 2 years related to demographics, lifestyle factors, and medical diagnoses. They completed food frequency questionnaires (FFQs) every 4 years. Based on FFQs, scores were given for 2 empirical dietary patterns (Western and prudent) and 3 indices related to dietary recommendations including Dietary Approaches to Stop Hypertension (DASH), Alternative Mediterranean Diet (AMED) and Alternative Healthy Eating Index (AHEI-2010). For these indices, a higher score reflects a higher diet quality. The authors captured data on adenomas and malignancy potential from colonoscopy results, as a marker for early onset CRC [i].
The authors found:
1. Those in the highest quintile of Western dietary pattern had an increased risk of early-onset adenoma compared to those in the lowest quintile
2. Those with a higher prudent pattern score had a decreased risk of early-onset adenoma
3. There were suggestions of higher DASH, AMED, and AHEI-2010 scores being associated with a decreased risk of early-onset adenoma
4. These associations were all significant for adenomas with higher malignancy potential, but not with low-risk adenoma
5. There was a stronger association between Western dietary pattern and risk of advanced adenomas specifically in the distal colon and rectum, but not in the proximal colon [i]
For the Patient and Caregiver
- A western dietary pattern is characterized by high intake of red and processed meats, high-fat dairy, refined grains, and desserts.
- A prudent dietary pattern is characterized by high intake of vegetables, fruits, whole grains, legumes, and fish [Supplementary Table 1 as referenced in i].
- DASH includes vegetables, fruits, whole grains, fat-free or low-fat dairy, fish and poultry, beans, nuts, and vegetable oils. It limits fatty meats, full-fat dairy, coconut and palm oils, sweets, and sugar-sweetened beverages.
- The mediterranean diet emphasizes plant foods such as whole grains, vegetables, legumes, fruit, nuts and seeds, herbs and spices, and olive oil, as well as fish, while limiting red meat and sweets.
- The HEI is based on the Dietary Guidelines for Americans which highlight vegetables, fruit, beans, whole grains, dairy, protein, and unsaturated fats, and recommend refined grains, added sugars, sodium, and saturated fats in moderation.
For the Healthcare Team
Findings related to anatomical site may be partially related to eating patterns. For example, the DASH diet is rich in calcium from low-fat dairy products, and previous findings show higher calcium intake to have an inverse association with CRC risk particularly in the distal colon [Zhang et al., 2016 as cited in reference i]. Encourage your patients to follow an eating pattern rich in whole, unprocessed foods, which DASH, AMED, AHEI-2010 and prudent all have in common.
[i] Zheng X, Hur J, Nguyen LH, Liu J, Song M, Wu K…Cao Y (2021). Comprehensive assessment of diet quality and risk of precursors of early-onset colorectal cancer. Journal of National Cancer Institute, 113(5). https://doi.org/10.1093/jnci/djaa164