Magnitude and Timing of the Postprandial Inflammatory Response to a High-Fat Meal in Healthy Adults: A Systematic Review

Abstract

Research findings over the past several decades have shown that inflammation is a prominent feature of many chronic diseases, with poor diet being one likely inflammatory stimulus. Specifically, a single high-fat meal (HFM) has been suggested to increase inflammation, although there is currently no consensus with regard to the specific changes in many of the proinflammatory markers that are frequently assessed after an HFM. The aim of this systematic review was to objectively describe the postprandial timing and magnitude of changes in 5 common inflammatory markers: interleukin (IL) 6, C-reactive protein (CRP), tumor necrosis factor (TNF) α, IL-1β, and IL-8. Ten relevant databases were searched, yielding 494 results, of which 47 articles met the pre-established inclusion criteria: 1) healthy men and women aged 18-60 y, 2) consuming a single HFM (≥30% fat, ≥500 kcal), and 3) assessing relevant inflammatory markers postmeal for ≥2 h. The only marker found to consistently change in the postprandial period was IL-6: on average, from a baseline of ∼1.4 pg/mL, it peaked at ∼2.9 pg/mL ∼6 h post-HFM (an average relative change of ∼100%). CRP, TNF-α, IL-1β, and IL-8 did not change significantly in 79% (23 of 29), 68% (19 of 28), 67% (2 of 3), and 75% (3 of 4) of included studies, respectively. We conclude that there is strong evidence that CRP and TNF-α are not responsive at the usual time scale observed in postprandial studies in healthy humans younger than age 60 y. However, future research should further investigate the role of IL-6 in the postprandial period, because it routinely increases even in healthy participants. We assert that the findings of this systematic review on markers of inflammation in the postprandial period will considerably aid in informing future research and advancing clinical knowledge.

Keywords: C-reactive protein; cytokine; interleukin; postmeal; tumor necrosis factor.

FIGURE 1

Flowchart of article search and selection process. Ten relevant databases were searched, yielding 494 total citations. The final number of citations included in the present study was 47. See Methods section for more details.

FIGURE 2

Post-HFM responses for the 5 assessed cytokines in healthy participants. The panels represent the change from fasting or baseline concentrations to the peak or maximally observed concentrations for IL-6 (A), CRP (B), TNF-α (C), IL-1β (D), and IL-8 (E). Open circles represent individual studies, and bars represent mean values. For markers other than IL-6, filled circles represent studies that found a significant change from pre- to postmeal, and open circles represent studies that found no significant postprandial change (difficult to differentiate with IL-6). For IL-6, CRP, and TNF-α, the data presented are after the removal of formal outliers. *Significant increase in IL-6 from fasting to peak value, P < 0.05. CRP, C-reactive protein; HFM, high-fat meal.

FIGURE 3

Correlations of several study variables with percentage change in IL-6 from pre- to post-HFM in healthy participants. The percentage change in IL-6 from baseline to peak or maximal observed response concentration was assessed for potential correlations with the percentage of energy from fat in the test meal (A), the energy content of the test meal (B), the mean BMI of the study participants (C), and the mean age of the study participants (D). The only variable that was found to have a significant correlation with percentage change in IL-6 was the percentage of fat in the test meal, which exhibited a moderate negative correlation.