Evaluation of the Influence of Whole and Defatted Flaxseed on Satiety, Glucose, and Leptin Levels of Women in the Late Postoperative Stage of Bariatric Surgery.

Satiety decline is one of the factors that are involved in weight regain in the postoperative period of bariatric surgery. Nutrients such as long chain n3 polyunsaturated fatty acid and fibers could assist in food intake control by increasing satiety. Flaxseed is a source of these nutrients, and its consumption could help with possible glycemic control and increased satiety. The aim of this study was to evaluate the influence of whole flaxseed and defatted flaxseed on satiety, postprandial blood glucose, and leptin in post-bariatric women. A single-blind crossover and randomized study was performed with 18 women in the late postoperative of Roux-en-Y gastric bypass (RYGBP). All women received three test meals containing whole flaxseed, defatted flaxseed, and placebo with 1 week of washout. Satiety was evaluated by a Visual Analog Scale during the fasting period; immediately after ingestion; and 60, 120, and 180 min after meals.There was no difference between test meals for the variables of hunger, satisfaction, fullness, and desire to eat. The basal and postprandial glucose and leptin levels did not differ between the test meals. The intake of defatted flaxseed and placebo muffins resulted in reduced postprandial blood glucose. Postprandial leptin was higher than the baseline (p  0.02); however, only defatted flaxseed showed increased postprandial leptin levels (p 0.044). Whole flaxseed and defatted flaxseed did not promote satiety in women in the late postoperative of RYGBP. However, the test meals with a lower fat content increased the serum leptin levels. (Authors abstract)
Bariatric surgery has become a growing option for the treatment of many individuals with severe obesity. It has been suggested that mechanisms that are related to weight loss after bariatric surgery, beyond caloric restriction, involve the participation of hormones that assist in food intake control, such as leptin, which is synthesized in the adipose tissue and plays an important role in the regulation of energy balance.  A decrease in satiety is one of the factors that cause the regain of lost body weight because patients begin to ingest more food over a long-term period. As a source of fiber and lipids, flaxseed can be used to assist in a possible increase in satiety with a consequent reduction in energy intake and glycemic control.  This study evaluated the influence of a flaxseed meal on satiety, glucose, and leptin levels of women in the late postoperative period of bariatric surgery. To date, this research is the first clinical study to evaluate the influence of flaxseed on the satiety of women in the late postoperative period of RYGBP and to suggest an alternative diet that could help in food intake control, avoiding lost weight regain after surgery.  In this study, 77 percent of the patients regained the excess lost weight, but showed appropriate lipemia and glycemia.  The regulation of these metabolic parameters can be observed after performing the RYGBP. To equal the amount of flaxseed (10 g) used in the test muffins (M1 and M2), some changes in the test meal composition were made, considering the difference in the composition of the whole and defatted flaxseed, which resulted in differences in macronutrients between them. The energy value did not differ between the muffins. In this study, consumption of M3 showed a greater fiber intake (10.1 g) compared to M1 and M2 but did not significantly influence any of the appetite sensations. The baseline and postprandial glucose and leptin levels did not differ between test meals, and only M2 intake showed a decrease in glucose and an increase in leptin in the postprandial time periods. 
The postprandial glucose decrease after M2 and M3 intake could be a result of the postprandial increase in plasma insulin after a meal with a higher content of carbohydrates and a meal with a higher content of fiber, respectively. With respect to the plasma glucose reduction after M2 intake, it is known that postprandial glucose depends on the relation between the secretion of glucagon and insulin and the amount and type of carbohydrates ingested. The glycemic peak depends on the amount of carbohydrates, the type and the meal composition and also on the time of the day that the meal is eaten; after breakfast, this peak is greater than at other points of the day. It is possible that M3 showed a reduction in the postprandial blood glucose because of its soluble fiber content.  Research that assesses the influence of macronutrients and fibers, as well as research that investigates the effect of certain foods on food intake and, consequently, on weight loss and weight maintenance, still have contradictory results because of the heterogeneity of the studies, such as the difference in experimental design; the characteristics of the studied populations such as gender, ethnicity, nutritional status, and level of physical activity; the type and amount of nutrient or food assessed; the type of control group; and the intervention time. (Editors comments)