Chickpeas and human health : the effect of chickpea consumption on some physiological and metabolic parameters

Pulses (legumes) are a common dietary constituent of ethnic communities exhibiting lower rates of cardiovascular disease (CVD). The following studies examined the effect of including chickpeas in an 'Australian' diet on CVD risk factors. Participants were free-living volunteers aged 30 to 70 years. Study 1 investigated the effect of chickpeas on serum lipids, lipoproteins, glycaemic control, bowel function and satiation (degree of fullness leading to meal cessation) compared to a higher-fibre wheat-supplemented diet (Chapter 2). Participants completed two controlled dietary interventions (chickpea-supplemented and higher-fibre wheat-supplemented), isocaloric with their usual dietary intake, in random order. The design of the intervention diets was for matched macronutrient content and dietary fibre however increased consumption of polyunsaturated fatty acids (PUFA) during the chickpea-supplemented diet was noted. Small but significant reductions in mean serum total cholesterol and low density lipoproteincholesterol (LDL-C) were reported following the chickpea diet compared to the wheat. Statistical analysis suggested a relationship between increased consumption of PUFA and reduction in cholesterol during the chickpea intervention but could not discern the source of PUFA. Chickpea supplementation did not adversely affect bowel function and participants found them very satiating. There was no effect on glycaemic control. A small, sub-study compared the effects of an isocaloric, lower-fibre wheat diet to the higher-fibre wheat, to evaluate the effect of quantity of fibre as well as source on bowel health and satiety. During the lower-fibre wheat intervention, some participants reported lower satiation, and poorer bowel health. Some of the results from this study were included in a larger, collaborative study investigating the effect of chickpeas on serum lipids and lipoproteins in two centres, Launceston and Melbourne. The Melbourne group followed a similar controlled, random crossover comparison of a chickpeasupplemented diet to a higher-fibre wheat-supplemented diet, also endeavouring to match macronutrient content and dietary fibre. The Melbourne group also reported small but significant reductions in mean serum LDL- and total cholesterol but reported discrepancies in consumption of PUFA as well as dietary fibre between the intervention diets. Statistical analysis of the combined results suggested a relationship between increased consumption of PUFA and dietary fibre and a reduction in cholesterol during the chickpea intervention. Appendix 1 is a description of this collaborative study, formatted as a scientific paper, accepted for publication. Study 2 investigated whether results from the controlled study would translate to ad libitum situations (Chapter 3). The study followed an ordered crossover design where participants followed their habitual ad libitum dietary intake for four weeks (familiarisation phase), incorporated a minimum of four 300g (net weight) cans of chickpeas per week for 12 weeks and then resumed their habitual diet for another four weeks (usual phase). Small but significant reductions in body weight, body mass index (BMI), serum TC, fasting insulin and HOMA-IR occurred following the chickpea phase, compared to the post-chickpea usual phase. Results suggested that participants positively altered their eating pattern during the pre-chickpea familiarisation phase, sustained these changes during the 12-week chickpea phase but regressed during the usual phase. Participants consumed significantly more dietary fibre and PUFA during the chickpea phase and less total fat and saturated fatty acids (SFA) compared to the usual phase. Perceived bowel health remained constant throughout the study, while satiation increased significantly during the chickpea phase along with a small but significant reduction in mean body weight. Incorporating chickpeas into an 'Australian' style diet resulted in increased consumption of PUFA and dietary fibre that produced small but significant reductions in serum TC, BMI and glycaemic control, high satiation and little effect on bowel function. Individuals wishing to reduce CVD risk may choose to include chickpeas in their diet.