Adipose Tissue Lipophilic Index and Risk of Ischemic Stroke-A Danish Case-Cohort Study

Diet may influence the risk of ischemic stroke by several mechanisms. A potential and hitherto unknown mechanism may relate to an effect on the lipophilic index, which is a new and convenient indicator of membrane fluidity. This study investigated the association between the adipose tissue lipophilic index and ischemic stroke and its subtypes. A case-cohort study was conducted based on the Danish cohort study Diet, Cancer, and Health, which includes 57,053 subjects aged 50–64 years at enrolment. A subcohort (n = 3500) was randomly drawn from the whole cohort. All ischemic stroke cases were validated and categorized into subtypes. The lipophilic index was calculated based on fatty acid profiles in adipose tissue. Subjects were divided into quintiles and a weighted Cox proportional hazards regression model was used to calculate hazard ratios. After appropriate exclusions, a subcohort of 3194 subjects and 1752 cases of ischemic stroke were included. When comparing the fifth quintile of the lipophilic index with the first quintile, the hazard ratio for ischemic stroke was 0.92 (95% confidence interval 0.75, 1.13) and the trend across quintiles was not statistically significant (p = 0.1727). In conclusion, no association was found between the lipophilic index and ischemic stroke or its subtypes.

Erythrocyte membrane fatty acid fluidity and risk of type 2 diabetes in the EPIC-Potsdam study

AIMS/HYPOTHESIS

The fluidity of cell membranes has been hypothesised as an important link in the association of fatty acids (FAs) with diabetes risk. The lipophilic index, which can be derived from the FA profile of blood or tissues, has recently been proposed as a novel measure of cell membrane FA fluidity. In this study we aimed to evaluate the lipophilic index in relation to the incidence of type 2 diabetes.

METHODS

We applied a nested case-cohort design (n = 1,740, including 362 cases) within the EPIC-Potsdam study, which involves 27,548 middle-aged men and women. Erythrocyte membrane FA proportions were measured at baseline and physician-confirmed incident diabetes was assessed during a mean follow-up of 7.0 years. The lipophilic index was calculated as the sum of the products of the FA proportions with the respective FA melting points.

RESULTS

After multivariable adjustments, including body size measures, there was a positive association between the lipophilic index and diabetes risk (HR comparing top with bottom quartile 1.59 (95% CI 1.08, 2.34), p for trend across quartiles = 0.005). Adjustment for FAs, which are considered established diabetes risk markers, did not substantially attenuate this association.

CONCLUSIONS/INTERPRETATION

A high lipophilic index, reflecting lower membrane fluidity, may be associated with a higher risk of type 2 diabetes. Our data corroborate the hypothesis that membrane fluidity may be an important mediator that links intake and metabolism of FAs to diabetes risk.

A novel fatty acid lipophilic index and risk of CHD in US men: the health professionals follow-up study

Few epidemiological studies have examined the association between an overall fatty acid (FA) profile and CHD risk. The aim of the present study was to examine a novel index that summarises individual FA levels based on FA affinity and fluidity in relation to CHD risk in men. In a prospective nested case–control study, FA in plasma and erythrocytes were measured in 459 CHD cases and 879 matched controls. Lipophilic index (LI) was computed by summing the products between FA levels and melting point of each FA to reflect the overall FA lipophilicity. Among controls, higher plasma LI was significantly correlated with adverse profiles of blood lipids, inflammatory markers and adiponectin. After multivariate adjustment for age, smoking, BMI and other CHD risk factors, plasma LI was significantly associated with an increased risk of CHD: the relative risk was 1·61 (95% CI 1·03, 2·53; P for trend¼0·04) comparing extreme quintiles. This association was attenuated to 1·21 (95% CI 0·48, 3·09; P for trend¼0·77) after adjusting for plasma levels of total trans-FA, long-chain n-3 FA and polyunsaturated:saturated fat ratio. Erythrocyte LI was not significantly associated with CHD risk. The present data indicate that a novel LI is associated with an adverse profile of cardiovascular risk markers and increased risk of CHD in men; its usefulness as a complement of individual FA in assessing disease risk needs to be elucidated in future studies.