Study: Phytochemical-Rich Foods Reduce Inflammation, Risk of Colorectal Cancer

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A Chinese study by J. Wu et al titled “Dietary phytochemical index and biomarker profiles are associated with colorectal cancer odds: integrating dietary intake with blood biomarkers” published on 15 September 2026 indicates that higher phytochemical and fibre intake is better for one’s health. The text is about 15 pages, including references.

One of the motivations is that few studies “have simultaneously evaluated dietary phytochemical intake together with gut barrier markers, inflammatory biomarkers, oxidative stress markers, metabolic indicators, and mediation analyses in relation to colorectal cancer”.

To capture overall dietary exposure to these compounds, the Phytochemical Index (PI), proposed by McCarty, estimates the percentage of total daily energy intake derived from phytochemical-rich foods.

Phytochemical-rich foods include fruits, vegetables, legumes, whole grains, olive oil and tea.

This study period was from January 2023 to December 2024 at two hospitals, one in Taiyuan and one in Nanchong. These two cities are about 1,000km apart.

The study involved 490 cancer cases matched to 490 cancer-free controls. Lifestyle information was collected for the 12-month period preceding the cancer diagnosis for the former or the interview date for the latter. Blood samples were subsequently taken; inflammatory, oxidative stress and antioxidant defense biomarkers, amongst other things, were analyzed.

The average age is about 61 years ± ~10 years, with more male (over 55%) than female. Perhaps not surprisingly, there were more drinkers and smokers in the cancer group as well as sleeping less and with lower quality sleep.

Generally, intestinal permeability and gut barrier dysfunction biomarkers such as zonulin, lipopolysaccharide-binding protein and D-lactate

…demonstrated progressively lower values across increasing PI tertiles in both study groups (all p < 0.05). These patterns suggest that higher phytochemical-rich food consumption was associated with better intestinal barrier integrity and reduced microbial translocation.

As for inflammatory, oxidative stress and tumor biomarkers,

…[s]ignificant inverse trends were observed for high-sensitivity C-reactive protein, interleukin-6, tumor necrosis factor-α, neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and systemic immune-inflammation index (all p < 0.01). Similarly, oxidative stress markers, including malondialdehyde and 8-hydroxy-2′-deoxyguanosine, showed lower concentrations across increasing tertiles, whereas antioxidant defense markers such as total antioxidant capacity, superoxide dismutase, and glutathione peroxidase showed progressively higher values (all p < 0.01).

As usual, correlation is not necessarily causation. Since those in the cancer group already have colorectal cancer, reverse causation is a possibility. That said, it is a large sample and the trends are similar across the tertiles for both groups with the control group having better numbers.

In short, those in the highest PI tertile compared to the lowest tertile have a reduction in odds of colorectal cancer of 52%.