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10-02-2011 | Cardiometabolic | Article

Dyslipidemic genetic predisposition does not prevent low-fat diet improving lipid profile

Abstract

Free abstract

MedWire News: Research suggests that a common genetic predisposition to dyslipidemia affects lipid profiles of patients on a habitual diet, but does not affect changes in lipid profiles due to reduced dietary intake of saturated fatty acids.

Celia Walker (Elsie Widdowson Laboratory, Cambridge, UK) and colleagues found that single nucleotide polymorphisms (SNPs) associated with lipid risk markers for cardiovascular disease were significantly associated with an unfavorable plasma lipid profile.

However, they found that none of the SNPs genotyped showed significant associations with reductions in plasma lipid levels in response to low-fat dietary interventions, and they found no evidence to support any direct diet-gene interactions.

The researchers examined associations between 39 lipid-associated SNPs and plasma lipid measures at baseline and after 24 weeks of dietary intervention in nearly 500 participants of the Reading, Imperial, Surrey, Cambridge, and Kings (RISCK) trial. Individuals in the RISCK trial were randomly assigned to receive a Western diet (reference), or a reduced saturated fat diet in which saturated fats were replaced by either carbohydrates or monosaturated fats.

As expected, higher genetic predisposition scores, which defined an individual's genetic susceptibility to an adverse lipid profile, were associated with higher baseline concentrations of total and low-density lipoprotein (LDL) cholesterol, triglycerides, and apolipoprotein (apo)B, and with lower concentrations of high-density lipoprotein (HDL) cholesterol and apoA-I.

However, reductions in total and LDL cholesterol, triglycerides, and apoB, and increases in HDL and apoA-I did not vary with increasing genetic predisposition score.

"Due to the nature of [the] highly controlled dietary interventions, we were limited to a relatively small sample size for investigating dietary-gene interactions," comment Walker et al.

Interestingly, the team notes that in response to 24 weeks of intervention, both the carbohydrate diet and genetic predisposition score for HDL cholesterol were significantly associated with a reduction in apoA-I.

The researchers say that this suggests that individuals genetically predisposed to low HDL cholesterol who also have low apoA-I may experience adverse effects on plasma lipid levels following a reduced saturated-fat diet where total fat is replaced with carbohydrate.

Writing in the journal Atherosclerosis, the team says: "Regardless of common genetic predisposition to dyslipidemia, improvements in lipid profiles can be achieved by changes to dietary fat quality and content."

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2011

By Nikki Withers