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Flax Seed Extract

Also known as: Linum usitatissimum L., Flaxseed, Linseed

Overview

Flaxseed, derived from the plant *Linum usitatissimum L.*, is a rich source of dietary fiber, alpha-linolenic acid (ALA), and lignans, which are phytoestrogens. It is commonly used as a dietary supplement to potentially support cardiovascular health, digestive health, and hormonal balance. Flaxseed is characterized by its high fiber content, omega-3 fatty acids, and lignans. Research on flaxseed is moderately mature, with several systematic reviews and meta-analyses available, although some areas lack comprehensive data. The available evidence is generally of good quality, with most studies employing RCT designs and adequate sample sizes, although some variability in outcomes and limitations in certain populations exist. Flaxseed is available in various forms, including whole seeds, ground flaxseed, flaxseed oil, and lignan extracts.

Benefits

Flaxseed has shown potential benefits in several areas. While a meta-analysis found no significant effect on sex hormones in the general population, subgroup analyses suggested potential benefits such as increased SHBG in subjects with PCOS and increased TT in men and subjects with prostate cancer. Another meta-analysis indicated that flaxseed may reduce CRP in obese populations, suggesting anti-inflammatory effects. Furthermore, flaxseed extracts have demonstrated antioxidant, anti-inflammatory, antimicrobial, and wound healing benefits in experimental studies. Other meta-analyses have shown that flaxseed can have beneficial effects on blood lipid profiles, such as reducing total cholesterol and LDL cholesterol. The duration of intervention impacts outcomes, with benefits more pronounced in studies lasting ≥12 weeks.

How it works

Flaxseed's effects are primarily attributed to its high content of ALA, lignans, and dietary fiber. Lignans may act as phytoestrogens, influencing hormonal balance by binding to estrogen receptors and affecting hormone metabolism. ALA, an omega-3 fatty acid, contributes to anti-inflammatory and cardiovascular health benefits by being metabolized into longer-chain omega-3 fatty acids, which can reduce inflammation. The high fiber content supports digestive health. The bioavailability of flaxseed components varies depending on the form (whole seed, oil, or lignan extract) and the presence of cofactors like water, which is necessary for the gel-like formation of soluble fiber.

Side effects

Flaxseed is generally considered safe when consumed in moderate amounts. Common side effects include gastrointestinal symptoms such as bloating, gas, and abdominal discomfort due to its high fiber content. Uncommon side effects include allergic reactions, though these are rare. Potential drug interactions exist, particularly with anticoagulant medications and estrogen-based therapies, due to its omega-3 content and lignan content. Caution is advised in individuals with severe gastrointestinal issues or those taking certain medications. Pregnant or breastfeeding women should consult healthcare providers due to the potential estrogenic effects of lignans. High doses may exacerbate gastrointestinal side effects.

Dosage

The minimum effective dose of flaxseed is not well-established, but typically 1-2 tablespoons (10-20 grams) of ground flaxseed per day is recommended. Optimal dosage ranges vary by study, but generally, 30-50 grams per day is used for fiber and omega-3 benefits. No upper limit has been definitively established, but high doses may exacerbate gastrointestinal side effects. It is best taken with water to aid in the formation of a gel-like substance that helps with fiber absorption. Ground flaxseed is more bioavailable than whole seeds. Flaxseed oil provides ALA but lacks fiber and lignans. A balanced diet and adequate hydration are recommended to support absorption.

FAQs

Is flaxseed safe to consume?

Flaxseed is generally safe, but individuals with certain health conditions or taking specific medications should consult healthcare providers before use.

How should I take flaxseed?

It is best taken with water, and ground flaxseed is preferred over whole seeds for better bioavailability.

What benefits can I expect from taking flaxseed?

Variable depending on the specific health outcome, but generally, benefits are seen in cardiovascular health, digestive health, and potentially in hormonal balance for specific populations.

Does flaxseed have significant estrogenic effects?

Flaxseed is often misconceived as having significant estrogenic effects, but recent evidence suggests these effects are minimal in adults.

Research Sources

https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2023.1222584/full – This systematic review and meta-analysis of 10 RCTs examined the effects of flaxseed supplementation on sex hormones. The study found no significant effect on sex hormones in the general population, but subgroup analyses showed potential benefits in specific conditions like increased SHBG in PCOS and increased TT in men with prostate cancer. Benefits were more pronounced in studies with an intervention duration of ≥12 weeks.
https://www.mdpi.com/2072-6643/8/3/136 – This meta-analysis investigated the effects of flaxseed and its derivatives on circulating C-reactive protein (CRP). The study did not find sufficient evidence that flaxseed reduces CRP in the general population. However, there was a suggestion that it may reduce CRP in obese populations, indicating potential anti-inflammatory effects in this group.
https://jppres.com/jppres/pdf/vol10/jppres21.1125_10.1.1.pdf – This systematic review explored the wound healing properties of flaxseed extracts and formulations. The review indicated that flaxseed has antioxidant, anti-inflammatory, antimicrobial, and wound healing benefits. The evidence is primarily from experimental studies rather than human clinical trials, highlighting the need for further research.
https://www.archivesofmedicalscience.com/A-systematic-review-and-meta-analysis-of-clinical-trials-investigating-the-effects,74141,0,2.html – This systematic review and meta-analysis investigated the effects of flaxseed on blood lipid profiles. The study showed that flaxseed can have beneficial effects on blood lipid profiles, such as reducing total cholesterol and LDL cholesterol. These findings support the use of flaxseed for cardiovascular health.
https://www.cochranelibrary.com/en/central/doi/10.1002/central/CN-00109267/related-content – This Cochrane Library entry refers to a systematic review and meta-analysis of clinical trials investigating the effects of flaxseed. The review provides evidence-based information on the potential benefits and limitations of flaxseed supplementation. It emphasizes the need for further research to fully understand its effects.