The Relationship of Dietary Cholesterol with Serum Low-Density Lipoprotein Cholesterol and Confounding by Reverse Causality : The INTERLIPID Study

• Published in: Journal of Atherosclerosis and Thrombosis 2019, Vol.26 (2), p.170-182
• Main Authors: Yukiko Okami, Hirotsugu Ueshima, Yasuyuki Nakamura, Nagako Okuda, Hideaki Nakagawa, Kiyomi Sakata, Shigeyuki Saitoh, Akira Okayama, Katsushi Yoshita, Sohel R.Choudhury, Queenie Chan, Paul Elliott, Jeremiah Stamler, Katsuyuki Miura, for the INTERMAP and INTERLIPID Research Groups
• Format: Article
• Language: Japanese
• ISSN: 1340-3478

[Aim]: The positive relationship between dietary cholesterol and serum cholesterol has been questioned by a set of recent cohort studies. This study aimed to investigate how employment status and education years relate to the association between dietary cholesterol and serum low-density lipoprotein cholesterol (LDL-C) in a Japanese population. [Methods]: A population-based, random sample, cross-sectional study (INTERLIPID) was performed. Among 1,145 Japanese individuals aged 40-59 years, 106 were excluded because of special diets, use of lipid-lowering drugs, hormone replacement, and missing data, leaving 1,039 individuals (533 men and 506 women). Dietary cholesterol was assessed from four 24-h dietary recalls, and LDL-C was measured enzymatically with an autoanalyzer. A standard questionnaire inquired about employment status and education years. [Results]: In men, a 1 standard deviation (SD) higher dietary cholesterol was associated with 3.16 mg/dL lower serum LDL-C (P=0.009; unadjusted model). After adjustment for covariates, higher serum LDL-C was estimated per 1 SD higher intake of dietary cholesterol in nonemployed men [self-employed, homemakers, farmers, fishermen, and retired employees; β=+9.08, 95% confidence interval (CI)=+0.90-+17.27] and less educated men (β=+4.46, 95% CI=-0.97-+9.90), whereas an inverse association was observed in employed men (β=-3.02, 95% CI=-5.49--0.54) and more educated men (β=-3.66, 95% CI=-6.25--1.07). [Conclusions]: In men who were nonemployed and less educated, a higher intake of dietary cholesterol was associated with elevated concentrations of serum LDL-C, whereas an inverse association was observed in men who were employed and more educated.