Long-term adherence to healthy dietary guidelines and chronic inflammation in the prospective Whitehall II study

Abstract

Background: Inflammation plays an important role in the cause of cardiovascular diseases and may contribute to the association linking an unhealthy diet to chronic age-related diseases. However, to date the long-term associations between diet and inflammation have been poorly described. Our aim was to assess the extent to which adherence to a healthy diet and dietary improvements over a 6-year exposure period prevented subsequent chronic inflammation over a 5-year follow-up in a large British population of men and women.

Methods: Data were drawn from 4600 adults (mean ± standard deviation, age 49.6 ± 6.1 years, 28% were women) from the prospective Whitehall cohort II study. Adherence to a healthy diet was measured using Alternative Healthy Eating Index (AHEI) scores in 1991-1993 (50.7 ± 11.9 points) and 1997-1999 (51.6 ± 12.4 points). Chronic inflammation, defined as average levels of serum interleukin-6 from 2 measures 5 years apart, was assessed in 1997-1999 and 2002-2004.

Results: After adjustment for sociodemographic factors, health behaviors, and health status, participants who maintained a high AHEI score (ie, a healthy diet, n = 1736, 37.7%) and those who improved this score over time (n = 681, 14.8%) showed significantly lower mean levels of interleukin-6 (1.84 pg/mL, 95% confidence interval [CI], 1.71-1.98 and 1.84 pg/mL, 95% CI, 1.70-1.99, respectively) than those who had a low AHEI score (n = 1594, 34.6%) over the 6-year exposure period (2.01 pg/mL, 95% CI, 1.87-2.17).

Conclusions: These data suggest that maintaining and improving adherence to healthy dietary recommendations may reduce the risk of long-term inflammation.

Keywords: Alternative Healthy Eating Index; Diet quality indices; Inflammatory marker; Interleukin-6; Middle-aged population; Nutritional Epidemiology; Prospective cohort.

Appendix Figure 1

Difference in average interleukin-6 levels (1997/1999 and 2002/2004) as a function of high versus low overall AHEI score and AHEI component scores at baseline (1991/1993) in 4600 participants from the Whitehall II cohort. AHEI = Alternative Healthy Eating Index; IL = interleukin; PUFA = polyunsaturated fatty acid; SatF = saturated fat.

Figure 1

Flow chart mapping the selection of the 4600 Whitehall II participants included in the present analyses.

Figure 2

Average levels of IL-6 over 2 measures 5 years apart according to 6-year changes in the AHEI score among 4600 participants from the Whitehall II cohort. Adjusted geometric mean levels of IL-6 were estimated from linear regression models for 4 categories: participants who maintained a low AHEI score over the exposure period, participants who maintained high AHEI score, participants who increased their score, and participants who decreased their score. Models were fully adjusted for sex, age, ethnic group, socioeconomic status, use of anti-inflammatory drugs, living alone, smoking, physical activity, total energy intake, coronary heart diseases, hypertension, diabetes, body mass index, and high-density lipoprotein cholesterol. % difference (exp[regression coefficient] – 1)*100; a negative percentage difference expressed the percentage reduction in IL-6 levels in the relevant exposure group compared with the reference group.