The Tailored Diet Study: A pilot study on the effect of individual tailored dietary advice on blood lipids in Familial Hypercholesterolaemia patients in Otago and Southland

Abstract

Background: Cardiovascular disease (CVD) causes 19% of all deaths in New Zealand; the contribution of familial hypercholesterolaemia (FH) to this figure is unknown. FH is a genetic disorder, which disrupts the metabolism of low density lipoprotein cholesterol (LDL) and increases CVD risk dramatically. An excess mortality of more than 340 has been reported, if left untreated. Reduction in blood cholesterol, especially LDL, is crucial for this population. There are few studies of dietary intervention in people with FH but dietary advice generally focuses on heart healthy eating patterns. The aim of this study was to assess whether tailored dietary goals, focusing on heart healthy eating patterns, can improve blood lipids in people with FH, over six to eight weeks.

Methods: The Tailored Diet Study (TDS) is a pilot intervention study of dietary change in people with FH. It was a combined study involving two Master of Dietetic students, using the same intervention protocols and resources. Participants for this candidate were recruited from two medical centres in Gore, Southland and Tapanui, West Otago. Data was collected via two interviews with each individual, one pre-intervention and one post-intervention interview, In addition, two to three follow up telephone calls were made to each participant between these interviews. Dietary assessment techniques were a 24 hour recall and semi-quantitative food frequency questionnaire (FFQ) and dietary data was later entered into the nutrient analysis programme Kaiculator for analysis. Participants were given two resources; the specifically designed TDS resource booklet – “Healthy Eating for a Healthy Heart” and the New Zealand Heart Foundation resource booklet – “A Guide to Heart Healthy Eating”. Dietary assessment tools and the TDS resource booklet were pretested in a focus group prior to use in the study. Results: Thirteen participants were recruited in Gore and West Otago. A total of 25 participants were recruited from Otago and Southland. Ages in Gore and West Otago ranged from 45-49 years to 65+ years and ten were female. Dietary changes varied between individuals depending on dietary goals. There were no significant changes in mean lipid profiles after the intervention, however LDL was trending toward significance. When changes in lipids were separated by on or off statin treatment, only those not taking statins had a mean reduction in lipids (0.6mmol/L). Significant reductions in intake were observed for total fat, saturated fat, cholesterol and carbohydrate, as well as significant increases in monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), and fibre intake. When intake was analysed by food group, significant decreases in biscuits, eggs, grains/pasta, beef/veal and processed meats were found. Significant increases were observed for fruit, vegetables, fish/seafood, nuts/seeds and margarine intake. Following the intervention, participants reported enjoyment with the intervention and satisfaction at the dietary changes they had made. Conclusion: Dietary change remains an important factor for people with FH. A heart healthy eating pattern can reduce LDL by clinically significant levels. Further investigations into the use of this intervention in a larger sample size, with a more intensive intervention and longer follow up is warranted. This intervention could be as a model for programmes in clinics for FH and other lipid disorders. Keywords: Familial hypercholesterolaemia; cardiovascular disease; blood lipids; dietary intervention; statins