Calories in Flax Seeds

Updated July 2026 · Source: USDA FoodData Central

534
kcal
per 100g
18.3
g
Protein
42.2
g
Fat
28.9
g
Carbs
27.3
g
Fiber
55
kcal per tablespoon ground (10g)
534
kcal per 100g
149
kcal per oz (28g)
Flax Seeds nutrition facts per 100g
🌿27.3g fiber per 100g — second highest
🐟Rich ALA omega-3 — 16.7g per 100g
🔬Richest lignans — 75-800× more than other plants
Magnesium — 93% Daily Value
❤️Reduces blood pressure by 10 mmHg — RCT proven
⚠️Must be GROUND for nutrient absorption

🥜 Calculate Calories for Any Flax Seeds Weight

Weight28g

Nutrition Facts

Per 100g flax seeds

* % Daily Value based on a 2,000 kcal diet.


Quick summary: Flax seeds contain 534 calories per 100g — 55 kcal per tablespoon ground. The richest dietary source of lignans (800µg/100g — 75-800× more than any other plant). Rich in ALA omega-3 (16.7g/100g) and fiber (27.3g/100g). Must be ground for full nutrient absorption. A 2013 RCT found 30g daily reduced systolic blood pressure by 10 mmHg.

Vitamins & Minerals — per 100g

NutrientAmount% Daily ValueBar
Thiamine (B1)1.64mg137%
Magnesium392mg93%
Manganese2.48mg108%
Phosphorus642mg51%
Zinc4.34mg39%
Iron5.73mg32%
Vitamin B60.47mg28%
Potassium813mg17%
Folate87µg22%
Selenium25.4µg46%

Calories in Flax Seeds by Weight

WeightCaloriesFatProteinNet Carbs
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Macronutrient Breakdown — per 100g

Fat42.2g · 71% of calories
Protein18.3g · 14% of calories
Carbs28.9g · 7% of calories
Fiber27.3g (in carbs)

Net carbs: 1.6g/100g (most carbs are fiber: 27.3g/100g). MUST be ground to absorb nutrients — whole flax passes undigested. Richest lignan food (800µg/100g). Second richest plant ALA omega-3. Store ground flax in fridge.

Micronutrient Highlights

🔬
Lignans
800µg
Phytoestrogens
Richest food source — 75-800× more than other plants
🌿
Fiber
27.3g
97% DV
Second highest fiber food after chia
🐟
ALA Omega-3
16.7g
Fatty acid
Second richest plant source
Magnesium
392mg
93% DV
One of the richest plant sources
🔴
Iron
5.73mg
32% DV
Non-haem iron
Thiamine (B1)
1.64mg
137% DV
Carbohydrate metabolism

Flax Seed Benefits

Lignans — Richest Food Source

~800µg lignans per 100g — 75-800× more than any other plant food. Gut bacteria convert to enterolactone and enterodiol — phytoestrogens modulating oestrogen activity. Multiple large studies show high lignan intake associated with reduced breast cancer risk (particularly oestrogen-receptor-positive), reduced prostate cancer risk, and alleviation of menopausal symptoms.

Blood Pressure — Clinical Evidence

The 2013 FLAX-PAD trial found 30g ground flax daily for 6 months reduced systolic BP by 10 mmHg and diastolic by 7 mmHg in patients with peripheral artery disease — effects comparable to antihypertensive medication. One of the largest dietary blood pressure reductions ever documented in a controlled trial.

ALA Omega-3

16.7g ALA per 100g — second only to chia seeds. One tablespoon (10g) provides 2.35g ALA — meeting the entire adequate daily intake. Regular flax consumption reduces triglycerides, lowers inflammatory markers, and may improve insulin sensitivity.

Must Be Ground — Critical Requirement

Whole flax seeds pass largely undigested. The valuable ALA, lignans, and fiber are only available from ground or milled flax. A coffee grinder converts whole seeds in seconds. Store ground flax refrigerated or frozen as PUFA content makes it prone to oxidation at room temperature.

Is Flax Seeds Suitable for Your Diet?

Weight loss
Yes — high fiber, satiating
Keto
Yes — 1.6g net carbs/100g
Paleo
Yes
Gluten-free
Yes
Diabetic
Yes — reduces blood pressure
Vegan
Yes — egg substitute, omega-3
Vegetarian
Yes
Hormonal health
Richest lignan source

Frequently Asked Questions

How many calories in flax seeds?
Flax seeds have 534 calories per 100g. One tablespoon ground (10g): 55 kcal. One oz (28g): 149 kcal.
Do flax seeds need to be ground?
Yes — whole flax passes through largely intact with limited nutrient absorption. Grinding releases ALA omega-3, lignans, and fiber. Store ground flax in the refrigerator to prevent rancidity.
Are flax seeds good for hormones?
Yes — the richest source of lignans, converted by gut bacteria to phytoestrogens. Research shows flax reduces breast cancer risk, alleviates menopausal hot flashes, and improves hormonal balance.
Do flax seeds lower blood pressure?
Yes — the 2013 FLAX-PAD trial found 30g ground flax daily reduced systolic BP by 10 mmHg and diastolic by 7 mmHg — one of the largest dietary blood pressure reductions ever recorded.
Are flax seeds keto?
Yes — only 1.6g net carbs per 100g. One tablespoon has just 0.16g net carbs. Extremely keto-friendly.
Chia vs flax seeds?
Chia: more fiber (34.4g vs 27.3g), more calcium, absorbs more water. Flax: more lignans, more ALA per gram, more thiamine. Must grind flax; chia can be eaten whole. Both are excellent.

Nutrition values from USDA FoodData Central. Not medical advice.