Diet is an important aspect of health behavior that has implications for inflammatory markers, with findings generally suggesting that diets high in fats are associated with increases in markers of inflammation. Below, research is reviewed to indicate that diet should be taken into account during analysis of inflammatory markers, with both consideration of dietary content, as well as changes in body weight.
Studies have compared the association between dietary patterns that are characterized as “prudent” (e.g., higher intake of fruit, vegetables, legumes, fish, poultry, and whole grains) versus those that are characterized as “Western” (e.g., higher intake of red and processed meats, sweets, desserts, French fries, and refined grains). The prudent dietary pattern was associated with lower levels of plasma concentrations of C-reactive protein (CRP) and E-selectin, a marker of endothelial activation. Importantly, these relationships remained robust even after adjustment for age, body mass index (BMI), physical activity, smoking status, and alcohol consumption (2
). In contrast, the Western dietary pattern was associated with higher levels of CRP and the endothelial markers of activation, E-selectin, soluble intercellular adhesion molecule (sICAM-1) and soluble vascular adhesion molecule (sVCAM-1) after adjustment for all confounders.
In another epidemiological study (N= 5089), four dietary patterns were statistically derived from food questionnaires. As with the findings for the Western diet, higher intake of the fats and processed meats pattern was associated with higher levels of CRP, interleukin-6 (IL-6), and homocysteine (3
). In addition, higher intake of the beans, tomatoes, and refined grains pattern was associated with higher levels of sICAM-1. In contrast, higher intake of the whole grains and fruit pattern was associated with lower levels of CRP, IL-6, homocysteine and sICAM-1, and the vegetables and fish pattern was also associated with lower levels of IL-6. These results were found after controlling for demographics and lifestyle factors and were not modified by race/ethnicity.
With regard to specific foods, a cross-sectional study of 730 women from the Nurses' Health Study found that trans fatty acid intake was positively related to plasma concentration of CRP, soluble tumor necrosis factor receptor II (sTNFR-II), sICAM-1, and sVCAM-1 in linear regression models after controlling for age, BMI, physical activity, smoking status, alcohol consumption, intake of monounsaturated, polyunsaturated, and saturated fatty acids, and postmenopausal hormone therapy (4
). In contrast, a high-fiber diet was associated with lower plasma levels of IL-6 and TNF-RII in the Women’s Health initiative Observational Study. However, there was no association with CRP in these postmenopausal women (5
Another aspect of diet that might impact inflammation is body weight and/or changes in body weight. For example, experimental weight loss has demonstrated that changes in daily dietary fat consumption modulates inflammatory markers (6
). Twenty-nine overweight women (average BMI: 32.1 kg/m2
) were randomly assigned to a high fat, low carbohydrate diet, or a low fat, high carbohydrate diet for four weeks. CRP increased 25% in the high fat, low carbohydrate group, even though they lost more weight than the low fat, high carbohydrate group. In contrast, CRP was reduced 43% in the low fat, high carbohydrate group. For both groups, IL-6 increased at the end of four weeks, despite overall weight loss. Together, these data suggest that dietary patterns that include higher intake of fat are associated with higher levels of markers of inflammation.