Flaxseed: what it contains and why it matters
Flaxseed is the seeds of the flax plant (alsi). This page lists its nutritional content from published sources and explains which lab parameters it relates to.
Last reviewed: 2026-09-04
Nutritional content of flaxseed
Per 100 g edible portion, from published composition data.
| Nutrient | Per 100 g | Source |
|---|---|---|
| Energy | 534 kcal | USDA |
| Protein | 18.29 g | USDA |
| Total lipid (fat) | 42.16 g | USDA |
| Carbohydrate, by difference | 28.88 g | USDA |
| Fiber, total dietary | 27.3 g | USDA |
| Magnesium | 392 mg | USDA |
| Potassium | 813 mg | USDA |
| Calcium | 255 mg | USDA |
| Iron | 5.73 mg | USDA |
| Phosphorus | 642 mg | USDA |
Which lab parameters does flaxseed relate to?
Magnesium
Magnesium supports muscle and nerve function and helps build bone [WHO].
Understand your Magnesium result →See all magnesium-rich foods →
Potassium
Potassium helps nerves and muscles work and helps balance the body's fluids [WHO].
Protein
Dietary protein provides the amino acids the body uses to build and repair tissue [WHO].
Vegetarian and dietary notes
Flaxseed is an unrefined plant seed suitable for vegetarian and vegan diets.
Frequently asked questions
What type of fatty acids are present in flaxseed?
Flaxseed is composed predominantly of polyunsaturated fatty acids, providing approximately 28.7 g of polyunsaturated fat per 100g [USDA], the majority of which is the omega-3 fatty acid alpha-linolenic acid (ALA).
How much dietary fiber is found in flaxseed?
Flaxseed contains 27.3 g of total dietary fiber per 100g [USDA], which includes both soluble mucilage gums and insoluble cellulose and lignin fractions.
What is the mineral profile of flaxseed?
Flaxseed provides several essential minerals, including 392 mg of magnesium, 813 mg of potassium, 642 mg of phosphorus, and 255 mg of calcium per 100g [USDA]. Magnesium serves as a cofactor in over 300 enzymatic reactions in the human body, while potassium functions as a primary intracellular electrolyte.
What is the protein content of flaxseed?
Flaxseed contains 18.29 g of protein per 100g [USDA], providing amino acids such as glutamic acid, arginine, and aspartic acid.
Does whole flaxseed differ from ground flaxseed in nutrient availability?
The outer seed coat of whole flaxseed consists of insoluble fiber that resists breakdown by digestive enzymes during gastrointestinal transit, whereas milling or grinding disrupts the hull and exposes the internal lipid and protein components for digestion.
Sources
- USDA — USDA FoodData Central, Agricultural Research Service. https://fdc.nal.usda.gov/
- WHO — World Health Organization — nutrition fact sheets. https://www.who.int/