Dietary modifications for managing familial hypercholesterolaemia

Familial hypercholesterolaemia is an inherited disorder characterised by a raised blood cholesterol, and premature ischaemic heart disease. Changing diet is an important management option to reduce low-density lipoprotein cholesterol (the bad cholesterol) levels. Recently, certain lipid-lowering drugs have shown to be safe and effective for the treatment of children with familial hypercholesterolaemia. However, dietary management remains important either on its own or combined with drug therapy. Several strategies are used to modify diet. This review aimed to compare cholesterol-lowering dietary interventions either in combination with each other or alone. These interventions included adding omega-3 fatty acids or plant sterols or plant stanols or soya proteins to diet. Fifteen trials were included in this updated review. The included trials had either a low or unclear risk of bias for most of the domains used for risk assessment. All the trials were short term and the majority were cross-over in design. For most of the comparisons there was no significant difference in the various intervention strategies when compared to cholesterol-lowering diet. However, for total cholesterol levels, serum low density lipoprotein (LDL) concentrations, a significant benefit was obtained with plant sterols. However, before drawing any conclusions, methodological problems with pooling results from cross-over trials should be considered. There is a need for long-term trials with parallel group design to assess the potential benefits and harms of a cholesterol-lowering diet.

Authors' conclusions: 

No conclusions can be made about the effectiveness of a cholesterol-lowering diet, or any of the other dietary interventions suggested for familial hypercholesterolaemia, for the primary outcomes: evidence and incidence of ischaemic heart disease, number of deaths and age at death,due to the lack of data on these. Large, parallel, randomised controlled trials are needed to investigate the effectiveness of a cholesterol-lowering diet and the addition of omega-3 fatty acids, plant sterols or stanols, soya protein, dietary fibers to a cholesterol-lowering diet.

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Background: 

A cholesterol-lowering diet and several other dietary interventions have been suggested as a management approach either independently or as an adjuvant to drug therapy in children and adults with familial hypercholesterolaemia (FH). However, a consensus has yet to be reached on the most appropriate dietary treatment. Plant sterols are commonly used in FH although patients may know them by other names like phytosterols or stanols.

Objectives: 

To examine whether a cholesterol-lowering diet is more effective in reducing ischaemic heart disease and lowering cholesterol than no dietary intervention in children and adults with familial hypercholesterolaemia. Further, to compare the efficacy of supplementing a cholesterol-lowering diet with either omega-3 fatty acids, soya proteins, plant sterols or plant stanols.

Search strategy: 

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Inborn Errors of Metabolism Trials Register, which is compiled from electronic searches of the Cochrane Central Register of Controlled Trials (CENTRAL) (updated with each new issue of The Cochrane Library), quarterly searches of MEDLINE and the prospective handsearching of one journal - Journal of Inherited Metabolic Disease. Most recent search of the Group's Inborn Errors of Metabolism Trials Register: 22 August 2013. We also searched PubMed to 05 February 2012.

Selection criteria: 

Randomised controlled trials, both published and unpublished, where a cholesterol-lowering diet in children and adults with familial hypercholesterolaemia has been compared to other forms of dietary treatment or to no dietary intervention were included.

Data collection and analysis: 

Two authors independently assessed the trial eligibility and risk of bias and one extracted the data, with independent verification of data extraction by a colleague.

Main results: 

In the 2014 update of the review, 15 trials have been included, with a total of 453 participants across seven comparison groups. The included trials had either a low or unclear risk of bias for most of the parameters used for risk assessment. Only short-term outcomes could be assessed due to the short duration of follow up in the included trials. None of the primary outcomes, (incidence of ischaemic heart disease, number of deaths and age at death) were evaluated in any of the included trials. No significant differences were noted for the majority of secondary outcomes for any of the planned comparisons. However, a significant difference was found for the following comparisons and outcomes: for the comparison between plant sterols and cholesterol-lowering diet (in favour of plant sterols), total cholesterol levels, mean difference 0.30 mmol/l (95% confidence interval 0.12 to 0.48); decreased serum LDL cholesterol, mean difference -0.60 mmol/l (95% CI -0.89 to -0.31). Fasting serum HDL cholesterol levels were elevated, mean difference -0.04 mmol/l (95% CI -0.11 to 0.03) and serum triglyceride concentration was reduced, mean difference -0.03 mmol/l (95% CI -0.15 to -0.09), although these changes were not statistically significant. Similarly, guar gum when given as an add on therapy to bezafibrate reduced total cholesterol and LDL levels as compared to bezafibrate alone.

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