Int J Food Sci Nutr. , 2022., Mar 20:1-12. doi: 10.1080/09637486.2022.2052820.

Brown and golden flaxseed reduce intestinal permeability and endotoxemia, and improve the lipid profile in perimenopausal overweight women.

Sant'Ana CT Amorim AD Gava AP et al.


The effect of brown and golden flaxseeds on lipid profile, oxidative stress, intestinal permeability, endotoxemia, and fasting glycaemia of perimenopausal overweight women was investigated in this clinical trial. Thirty participants were divided into control (CG), brown flaxseed (BF), and golden flaxseed (GF) groups. BF and GF received 40 g of brown and golden flaxseed for 12 weeks. Venous blood samples were collected at the beginning and at the end. Intestinal permeability analysis was performed by urinary excretion of lactulose and mannitol. There was significant reduction in intestinal permeability in flaxseed groups, with delta of lactulose/mannitol ratio smaller (p ≤ 0.05). LPS levels were reduced in the flaxseed groups, whereas low-density lipoproteins (LDL) was decreased in the GF group (p ≤ 0.05). Flaxseed consumption did not change oxidative stress markers and glycaemia. Flaxseed consumption, especially golden flaxseed, reduced intestinal permeability and improved the lipid profile, showing positive effects on metabolic changes caused by menopausal transition. Brown and golden flaxseeds show a high content of insoluble fibre and alpha-linolenic acid, and  brown flaxseed presented higher antioxidant activity. Golden flaxseed improved the lipid profile. Brown and golden flaxseeds reduced intestinal permeability and endotoxemia. Brown and golden flaxseed can be a promising alternative for the prevention of metabolic changes caused by menopausal transition, and for the improvement of the intestinal health.

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Key Points

The hypothesis of this study was that the consumption of brown flaxseed would develop results better or similar to golden flaxseed in relation to improving clinical manifestations related to menopausal transition, including  lipid and glucose metabolisms, oxidative stress, intestinal permeability, and endotoxemia in perimenopausal women. Brown and golden flaxseeds have similar phenolic content, but the antioxidant activity of the brown flaxseed was found to be greater than the golden, indicating that the antioxidant activity is not related only to the phenolic content, and that other compounds present in the brown flaxseed favour the greater antioxidant activity. Significant reduction in the delta for LDL-c in GF group, was found which demonstrates that golden flaxseed contributes to lowering this risk factor of atheromatous plaque formation, and consequently may prevent cardiovascular problems. The reduction in LDL-c observed may be attributed to fibres and phenolic compounds present in flaxseeds. SDG in flax contributes to the regulation of cholesterol metabolism by acting on the expression of the enzyme that regulates the synthesis of bile salts. Therefore, a higher excretion of hepatic cholesterol in the bile may occur upon increased intake of flaxseed. Soluble fibres act by reducing intestinal absorption of cholesterol by adsorbing water and forming gels, hence contributing to the delay of gastrointestinal emptying and, as a result, to the decrease of glucose and cholesterol absorptions in the small intestine.

In the present study, no significant changes were observed in blood glucose levels between the control group and the groups that consumed brown and golden flaxseeds. In the menopausal transition, hormonal changes can trigger metabolic alterations, such as weight gain, that can consequently result in insulin sensitivity alterations and lead to the development of diabetes. Brown and golden flaxseed reduced permeability to mannitol and lactulose, and LPL levels in flaxseed groups after 12 weeks of intervention. Thus, the daily administration of 40 g of brown and golden flaxseed was shown to be capable of improving the intestinal barrier function and integrity by reducing the translocation of endotoxins responsible for the increase of inflammation. These results demonstrated a beneficial effect of both flaxseeds on intestinal health.  Both flaxseed supplementations were efficient to reduce intestinal permeability and endotoxemia, resulting in improved intestinal health. Golden flaxseed reduced the LDL-c fraction, indicating a cardio-protective effect.