Avocados: consumer beliefs and effect on weight loss and markers of cardiovascular health
Motivation - The objective of the South African Avocado Growers Association (SAAGA) is to increase the demand of avocados by advertising, promoting and other means deemed fit by them. In order to promote and advertise a product, consumer research has to be done to determine the consumers' attitudes towards and beliefs concerning the product. These findings then need to be followed up by scientific studies, targeted at specific problems and target groups to yield scientific evidence. Little consumer research has been done on avocados and studies investigating the health effects of avocados are limited, with available literature only focusing on the cholesterol lowering effect of avocados. Objectives - Firstly, the objective is to investigate the beliefs and attitudes of the South African consumer towards avocados and health; to determine whether gender, age group, race or living standard influence the consumers beliefs towards avocados. Secondly, the objective is to dispel the myth that avocados are fattening and should therefore be avoided in energy restricted diets; to examine the effects of avocados, a rich source of monounsaturated fatty acids, as part of an energy restricted diet on weight loss, serum lipids, fibrinogen and vascular function in overweight and obese subjects. Methods - Consumer study: One thousand nine hundred and ninety-seven South African individuals, randomly selected from metropolitan areas in South Africa, participated in this survey. Data were weighed to reflect the adult metropolitan population based on gender, age and race distribution. The total population (10 695 000) was representative of both genders (5 423 000 men and 5 272 000 women) and major race groups (2 615 000 whites, 6 252 000 blacks, 1 255 000 coloureds and 573 000 Indians) from different age groups and living standards. The questionnaires were designed by a multidisciplinary team and consisted of seventeen food related questionnaires, of which one questioned the beliefs regarding avocados. Trained field workers administrated questionnaires by conducting face-to-face interviews with consumers. The market research company, MARKINOR, was contracted to collect the data. Quantitative data was statistically analysed in order to generate the relevant descriptive statistics, cross tabulations and statistical tests. Dietary intervention study: Sixty one free-living volunteers (13 men; 48 women), with a mean (standard deviation) body mass index (BMI) of 32 (3.9) kg/m2, participated in this randomised, controlled parallel study. The subjects were paired according to gender, BMI and age and randomly assigned to one of two groups. The experimental group consumed 200 g of avocado (1 avocado) per day, substituting 30 g of other mixed dietary fats, and the control group excluded avocado from their energy restricted diet for six weeks. Seven-day isoenergetic menu plans were given according to mean energy requirements of both genders to provide 30% fat, 55% carbohydrates and 15% protein of total energy intake. Anthropometric measurements, physical activity, dietary intakes, blood pressure and arterial compliance were measured with standard methods at the beginning and end of the intervention. Fasting blood samples were drawn at the beginning and end of the intervention period. Results - Consumer study: There were no practical significant differences in the consumers responses in terms of gender or age. Practical significant differences were found between different race and LSM (Living Standard Measure) groups for some variables. The overall response of consumers towards the effect of avocados on health, heart health, children's health and the health effects associated with the fat content of avocados were very positive. However, almost half the consumers are still not convinced of or are uncertain as to the cholesterol content of avocados, while 47% of the consumers still believe that avocados are fattening. More than 80% of the consumers agreed that avocados are a good source of vitamins and minerals, and 76% consider avocados to be a good source of fibre. Almost 70% of the consumers agreed that avocados are good for sportsmen and -women. Avocados were seen by 49% of the consumers to be an aphrodisiac. Dietary intervention study: Fifty-five subjects completed the study. Compliance with avocado intake in the experimental group was 94.6%. Anthropometric measurements (weight, body mass index and percentage body fat) decreased significantly in both groups during the study (p<0.001), and the change was similar in both groups. Serum lipid levels (total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and triglycerides), fibrinogen, blood pressure and arterial compliance did not change significantly within or between the two groups. Conclusions - Consumer study: There are still a few myths and misconceptions that exist among some consumers regarding avocados, especially with regard to sexual functioning, cholesterol content, and fattening effect of avocados. The agricultural industry can use these results to plan different marketing campaigns focused on certain target groups to change the misperceptions concerning avocados and convey the positive nutritional value of avocados. Dietary intervention study: The consumption of 200 g avocado per day, within an energy restricted diet, does not compromise weight loss when substituted for 30 g of mixed dietary fat. The serum lipid levels, plasma fibrinogen, arterial compliance, as well as systolic and diastolic blood pressure were not affected by weight loss or avocado intake.
- Health Sciences