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Flaxseed

Linum usitatissimum

Also known as Linseed, Common flax

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The seed of the flax plant, sold whole, ground or pressed for oil, and the densest common dietary source of plant lignans. The USDA reference entry is for the whole seed.

Heart HealthGut & Digestive HealthWomen's Health

Potential health benefits

Best supported: Moderate

Ordered by how well the human research supports them — strongest first. A rating describes the state of the evidence, not how impressive the food is. How we rate evidence.

Blood lipid profile

Heart Health
Moderate evidence

Some trials report small reductions in LDL and total cholesterol with whole ground flaxseed, though results vary with the form used and effects are weaker for flaxseed oil than for the ground seed.

Moderate evidence. Several human studies point the same way, with real caveats.

1 source

Deep research mode adds each paper’s own conclusion and stated limitations.

Bowel regularity

Gut & Digestive Health
Moderate evidence

Several trials report increased stool frequency and softer stools with ground flaxseed, consistent with the general effect of viscous soluble fibre plus the insoluble fraction of the seed coat.

Moderate evidence. Several human studies point the same way, with real caveats.

1 source

Deep research mode adds each paper’s own conclusion and stated limitations.

Healthy blood pressure

Heart Health
Moderate evidence

Several trials and meta-analyses report modest reductions in systolic and diastolic blood pressure with daily ground flaxseed, with larger effects in trials lasting more than about three months.

Moderate evidence. Several human studies point the same way, with real caveats.

2 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Menopausal symptoms

Women's Health
Insufficient evidence

Flaxseed lignans are widely promoted for hot flushes, and the randomised trials do not support it. Where placebo-controlled trials exist, flaxseed has generally performed no better than placebo, despite large improvements in both arms.

Insufficient evidence. Not enough human research to say anything useful yet.

2 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Ask about Flaxseed

Ask about Flaxseed

Answers are written only from the entries on this page — the same nutrients, compounds, claims and citations you can read above. Nothing is added from outside the database, and every answer lists what it was built from.

AI explanations are not switched on for this site, so there is nothing to ask here. Everything above is read straight from the database and does not need them.

Key nutrients

Nutrient content per 100 grams
NutrientAmount% DV
Macronutrients
Calories534 kcal27%
Protein18.3 g37%
Total fat42.2 g54%
Carbohydrate28.9 g11%
Fibre27.3 g98%
Total sugars1.55 g—
Water6.96 g—
Fats
Saturated fat3.66 g18%
Monounsaturated fat7.53 g—
Polyunsaturated fat28.7 g—
Cholesterol0 mg0%
EPA (omega-3)0 g—
DHA (omega-3)0 g—
DPA (omega-3)0 g—
Linoleic acid (omega-6)5.9 g—
Vitamins
Vitamin A0 µg0%
Vitamin C0.6 mg1%
Vitamin D0 µg0%
Vitamin E0.31 mg2%
Vitamin K4.3 µg4%
Thiamin (B1)1.64 mg137%
Riboflavin (B2)0.161 mg12%
Niacin (B3)3.08 mg19%
Pantothenic acid (B5)0.985 mg20%
Vitamin B60.473 mg28%
Folate87 µg22%
Vitamin B120 µg0%
Choline78.7 mg14%
Minerals
Calcium255 mg20%
Iron5.73 mg32%
Magnesium392 mg93%
Phosphorus642 mg51%
Potassium813 mg17%
Sodium30 mg1%
Zinc4.34 mg39%
Copper1.22 mg136%
Manganese2.48 mg108%
Selenium25.4 µg46%
Other measured compounds
Beta-carotene0 µg—
Alpha-carotene0 µg—
Lycopene0 µg—
Lutein + zeaxanthin651 µg—
Caffeine0 mg—
Ash3.72 g—

Nutrient values are per 100 g of the USDA reference entry named on this page and vary with variety, growing conditions, storage and preparation.

Source record: Seeds, flaxseed (USDA FoodData Central, FDC ID 169414).

% DV uses the FDA Daily Values for adults and children aged 4 and over. A dash means no Daily Value has been established for that nutrient.

Bioactive compounds

Compounds present in meaningful amounts. Presence is banded rather than quantified, because whole-food levels vary enormously with variety, growing conditions, storage and preparation.

How preparation changes things

Only effects with real support are listed. If a preparation method is missing, it is because nothing dependable is documented — not because it makes no difference.

  • groundIncreases lignan and ALA availability

    Grinding ruptures the seed coat and is required for the lignans and the ALA to become available; whole seeds pass through the digestive tract largely intact. This is the single most consequential preparation step for this food.

  • cookedReduces cyanogenic glycosides

    Baking and other heating reduce cyanogenic glycoside content, while the lignans are comparatively heat-stable.

Things to know

Allergies, interactions and intake concerns. Every food gets this section — a reference where everything is uniformly good is not a reference.

  • Too much

    Cyanogenic glycosides

    Flaxseed contains cyanogenic glycosides that release small amounts of hydrogen cyanide. Ordinary culinary amounts are well within the range regulators consider safe, and baking and cooking reduce them further, but very large daily intakes of raw seed have raised concern and are not advisable.

  • Worth knowing

    Whole seeds pass through undigested

    The seed coat is tough enough that whole flaxseeds largely pass through the gut intact, so neither the lignans nor the fat are meaningfully available. Grinding is not a refinement here, it is the requirement.

  • Interaction

    Medication timing and bowel obstruction

    The viscous fibre can slow the absorption of medicines taken at the same time, so a gap is usually advised. Large amounts taken without adequate fluid have been linked to bowel obstruction, and flaxseed is generally avoided in people with a known bowel stricture.

  • Worth knowing

    Rapid rancidity once ground

    Ground flaxseed oxidises quickly because of its high polyunsaturated fat content. Grinding in small batches and refrigerating the result is the usual advice.