Higher serum concentrations of myristoleic acid, gadoleic acid, erucic acid, and nervonic acid, along with a lower concentration of palmitoleic acid, are associated with an increased risk of colorectal cancer.

The association between serum concentrations of total monounsaturated fatty acids (MUFAs) and colorectal cancer (CRC) risk remains controversial, with limited evidence regarding individual MUFAs. This study aimed to comprehensively explore the associations of serum MUFA concentrations with CRC risk in a Chinese population. We hypothesize that serum myristoleic acid (C14:1), oleic acid (C18:1), gadoleic acid (C20:1), erucic acid (C22:1), nervonic acid (C24:1) and total MUFAs are positively associated, while palmitoleic acid (C16:1) is inversely associated with CRC risk. Serum MUFA concentrations were measured by gas chromatography in 680 cases and 680 frequency-matched controls aged 30 to 75 years. Multivariable logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). We observed no significant linear associations for serum total MUFAs (adjusted OR [aOR] for quartile 4 vs. quartile 1, 1.37; 95% CI, 0.83-2.28), or serum C18:1 (aOR, 0.81; 95% CI, 0.50-1.32) with CRC risk; instead, both exhibited inverted-U trends peaking at 16.66% and 13.23%, respectively. However, serum concentrations of C14:1 (aOR, 2.23; 95% CI, 1.56-3.18), C20:1 (aOR, 1.98; 95% CI, 1.40-2.80), C22:1 (aOR, 1.83; 95% CI, 1.28-2.62), and C24:1 (aOR, 6.33; 95% CI, 4.25-9.42) were positively associated with CRC risk, whereas serum C16:1 (aOR, 0.48; 95% CI, 0.33-0.71) was inversely associated with CRC risk. These findings suggest that different serum MUFA subtypes exhibit differing associations with CRC risk. Higher serum concentrations of C14:1, C20:1, C22:1, C24:1 and lower concentration of C16:1 are associated with an increased CRC risk in Chinese population. It may be beneficial for CRC prevention to appropriately increase the dietary intake of C16:1-rich foods such as Macadamia nut or palm oil.