By Kelley Fitzpatrick, Content Editor
Obesity is a global epidemic associated with diabetes, hypertension, cardiovascular disease and some cancers. The global obese population has grown to 641 million and has exceeded those considered underweight, according to recent data published in The Lancet (1). The report which included 700 researchers worldwide analyzed data on weight and height from nearly 20 million adults from 186 countries. The analysis showed that over the past 40 years, the average age-corrected male BMI rose from 21.7 to 24.2 and in women rose from 22.1 to 24.4. The investigators predicted that if these global trends continue, 18% of men and 21% of women globally will be obese by 2025.
Strategies are obviously necessary to curb the epidemic of obesity and its consequences. Dietary modification to reduce caloric intake has been the focus of weight loss and weight control programs. A variety of food components contribute to satiety and thus weight management. Fibre, particularly soluble fibre, may help to promote weight loss or prevent weight gain by absorbing large quantities of water to induce a feeling of fullness and delay gastric emptying (2).
High fibre diets are associated with increased satiety, reduced hunger and energy intake, and weight loss. Results of a systematic review reported that high fibre diets (providing an additional 14 g/day of fibre) among overweight and obese individuals reduced energy intakes to 82% of control and resulted in an average weight loss of 2.4 kg. Such diets may even have a more pronounced effect among overweight and obese individuals by reducing energy intakes to 82 per cent of control and resulting in an average weight loss of 2.4 kilograms (3).
Flaxseed is a rich source of dietary fibre, providing 16% of the recommended daily intake in a 2 tablespoon serving. Beverages or tablets containing 2.5 g of flaxseed soluble fibre significantly reduced energy intake compared to control (702 vs. 768 kcal) (4). Subjective measures of satiety and fullness increased, while hunger and prospective food intake decreased.
In another study, a flaxseed dietary fibre extract lowered post-prandial insulin following meals in comparison to either no or whole flaxseed (5). Satiety and fullness were higher after the flaxseed fibre treatment compared to control.
Accumulating evidence supports the role that milled flaxseed and flaxseed oil may play in weight loss and maintenance. An approximate 4% gain in body weight and BMI from baseline was reported in a control group not fed flaxseed compared to individuals with type 2 diabetes that consumed 32 g/day milled flaxseed or 13 g/day flaxseed oil for 12 weeks. The waist circumference of those fed milled flaxseed decreased by 5 cm during the treatment period (6).
Most recently, the efficacy of flaxseed supplementation plus lifestyle modifications for the management of metabolic syndrome (MetS) was assessed (7). MetS includes central obesity, dyslipidemia, elevated blood pressure, and hyperglycemia, which can lead to an increased for cardiovascular disease and diabetes. A randomized controlled 12 week clinical trial was conducted on 44 patients who received either lifestyle advice and 30 g brown milled flaxseed daily or only lifestyle advice as the control group. The percentage of individuals with MetS decreased from baseline by 50% and 82% in the control and intervention group, respectively. The reversion rate of central obesity was higher in the flaxseed group (36%) than control group (13%). A greater reduction in insulin resistance was observed in flaxseed group in comparison with control group. Body weight, waist circumference, and body mass index decreased significantly in both groups with a significantly greater reduction in flaxseed group in comparison with controls. These results indicate that flaxseed supplementation with lifestyle modification is more effective than lifestyle modification alone in management of MetS.
Research to-date examining the effectiveness of flaxseed and it components in weight loss and maintenance shows promise. Further studies with larger sample sizes and of longer duration are needed to examine these associations. The studies cited in this blog can be found in the “Weight” category of this website.
References
- Majid Ezzati et al. for the NCD Risk Factor Collaboration. 2016. Trends in adult body-mass index in 200 countries from 1975 to 2014: a pooled analysis of 1698 population-based measurement studies with 19·2 million participants. The Lancet. Vol 387 April 2. doi.org/10.1016/S0140-6736(16)30054-X.
- Kristensen and Jensen 2011. Dietary fibres in the regulation of appetite and food intake. Importance of viscosity. Appetite. Feb;56(1):65-70.
- Howarth et al. 2001. Dietary fiber and weight regulation. Nutr Rev. 59(5):129-39.
- Ibrügger et al. 2012. Flaxseed dietary fiber supplements for suppression of appetite and food intake. Appetite. 58(2):490-5.
- Kristensen M et al. 2013. Flaxseed dietary fibers suppress postprandial lipemia and appetite sensation in young men. Nutr Metab Cardiovasc Dis. 23(2):136-43.
- Taylor et al. 2010. Dietary milled flaxseed and flaxseed oil improve N-3 fatty acid status and do not affect glycemic control in individuals with well-controlled type 2 diabetes. J Am Coll Nutr. 29(1):72-80.
- Yari Z, et al. 2016. Flaxseed Supplementation in Metabolic Syndrome Management: A Pilot Randomized, Open-labeled, Controlled Study. Phytother Res. May 6. doi: 10.1002/ptr.5635.