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Flax

What does the research say about Flax?

3 health outcomes synthesised

Research on flaxseed oil has examined its effects on 3 health outcomes, primarily blood pressure and waist circumference. The strongest evidence, though still limited, points to potential reductions in systolic blood pressure, with 2 of 3 studies showing small beneficial effects. Doses around 25 mL/day have been used in studies on adults with metabolic syndrome, but the evidence base is too small to draw firm conclusions.

Strongest evidence: No outcomes reached high or moderate evidence strength; all three are rated low. The outcome with the most consistent beneficial signal is Reduced Systolic Blood Pressure — 2 of 3 studies reported small beneficial effects, while one meta-analysis found no significant effect.

Mixed or weaker evidence: For Reduced Diastolic Blood Pressure, only 1 of 3 studies showed a small benefit; 2 were neutral. Reduced Waist Circumference also had 1 beneficial study and 2 neutral. All syntheses emphasize that the evidence is too small to draw firm conclusions.

Effective dose patterns: The only dose that produced a beneficial effect in any study was 25 mL/day of flaxseed oil, used in a single 49-day RCT in adults with metabolic syndrome for both blood pressure and waist circumference. No convergence across studies exists.

Population insights: The beneficial studies focused on adults with metabolic syndrome; other populations (e.g., hemodialysis patients) showed neutral results. The evidence does not support benefits in normotensive individuals.

Notable caveats: All outcomes rely on only 3 studies each; many individual studies did not reach statistical significance. Meta-analyses found non-significant effects, raising the possibility of publication bias. Effects vary from small to large, and the form of flax (oil vs. whole seed) was not consistently reported.

Frequently asked

  • What is Flax good for according to research?
    Research on flaxseed oil has investigated its effects on three health outcomes: reducing systolic blood pressure, diastolic blood pressure, and waist circumference. However, all evidence is rated low strength, with most studies showing small or neutral effects. The most consistent signal is for systolic blood pressure, where 2 out of 3 studies reported a small benefit.
  • What dose of Flax is typically used in studies?
    The only dose that showed a beneficial effect in any study was 25 mL/day of flaxseed oil, used in a single 49-day RCT in adults with metabolic syndrome. Other studies did not converge on a specific dose, and the effective dose range remains unclear due to the small evidence base.
  • Who benefits most from Flax?
    Limited evidence suggests that adults with metabolic syndrome may experience small reductions in blood pressure and waist circumference with 25 mL/day of flaxseed oil. Other populations, such as hemodialysis patients, showed neutral results. No studies examined benefits in healthy individuals.
  • Are there caveats or limitations in the research on Flax?
    Yes, major caveats include a small evidence base (only 3 studies per outcome), many non-significant findings, and potential publication bias. The studies often did not reach statistical significance, and meta-analyses reported neutral overall effects. Additionally, the form of flax (oil vs. whole seed) was inconsistently reported.
  • Does Flax help with blood pressure?
    For systolic blood pressure, 2 of 3 studies reported a small beneficial effect, while one meta-analysis found no significant effect. For diastolic blood pressure, only 1 of 3 studies showed a small benefit. Overall, the evidence is low strength and preliminary, so firm conclusions cannot be drawn.
  • Does Flax help with waist circumference?
    Only 1 of 3 studies reported a small beneficial effect on waist circumference, using 25 mL/day of flaxseed oil in adults with metabolic syndrome. The other 2 studies found neutral results, and a meta-analysis showed no significant effect. The evidence is too limited to support a benefit.

Most-studied combinations with Flax

most supplement research is combination research
Also studied with:Olive Oil (2)

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