The Impact of Fish and Walnut Consumption on Cardiovascular Risk Factors in Overweight and Obese Females: A Randomized Clinical Trial

In this study, 99 overweight or obese women that referred to the Clinic Nutrition to lose weight were randomly divided into three groups according to body mass index (BMI) by random-number table (figure1). We attempted to match all three groups for BMI, probable medications, and age. Subjects were excluded if they had risk factors of cardiovascular diseases or allergic reactions to fish or walnut, or received lowering blood glucose or lipid profile agents. Also, participants with weak economic status could not enter to this study (due to the high cost of fish and walnuts). Before the start of this study, the information in the form of questionnaire about demographic, medical history, and medication use, was completed. Participants were aware about overview of this study, and completed the consent form. The NATIONAL INSTITUTED FOR MEDICAL RESEARCH DEVELOPMENT (NIMAD), approved all procedures involving human subjects. The study has been done in accordance with the ethical standards in declaration of Helsinki.

Then all of the three groups received a low-calorie diet in order to lose weight. The distribution of macronutrients was similar in three groups (carbohydrate 55%, fat 33%, and protein 17%). The amount of different fatty acids (saturated, unsaturated with mono double bond, and polyunsaturated fatty acids) intake in these diets was the same but the sources of omega-3 between these groups were different. In the first group, subjects were instructed to consume 300 gram fatty fish, such as Salmon fish during a week in two separated meals (each meal 150 gr fatty fish) and to avoid consumption of plant sources of omega-3 (soybean oil, canola, flaxseed and walnuts). In the second group, subjects were asked to consume walnuts three times a week and each time two walnuts (totally 18 walnuts/wk) and avoid the consumption of fish. And in the third group, subjects were recommended to consume 150 g fatty fish during a week and nine walnuts. The amount of omega-3 fatty acids considered in this study covered the typical recommended intake (0.3 to 0.5 g/d of EPA+DHA and 0.8 to 1.1 g/d of ALA)(14). Dietary intakes of all patients were controlled by a dietitian and they were followed for 12 weeks. Dietary intakes were assessed by three dietary records (one weekend and two week days).