Flax Seeds 101: Nutrition Facts and Health Benefits

Key Takeaways

• Flax seeds are small oil seeds rich in omega-3 fatty acids (especially ALA), fiber, and lignans — plant compounds that act as antioxidants and phytoestrogens.
• They may support heart health by helping lower LDL (bad) cholesterol and blood pressure, and their high fiber content can promote digestive regularity and help manage blood sugar.
• Grinding flax seeds before eating helps your body absorb more nutrients. Start with small amounts to avoid digestive discomfort, and talk with a healthcare professional if you’re pregnant, breastfeeding, or taking blood thinners.

Flax seeds (Linum usitatissimum) — also known as common flax or linseeds — are small oil seeds that originated in the Middle East thousands of years ago.

Lately, they have gained popularity as a health food. This is due to their high content of heart-healthy omega-3 fats, fiber, and other unique plant compounds.

Flax seeds have been linked to health benefits, such as improved digestion and a reduced risk of heart disease, type 2 diabetes, and cancer.

They’re easily incorporated into your diet — grinding them is the best way to make the most of their health benefits.

Flax seeds are usually brown or yellow. They’re sold whole, ground/milled, or roasted — and are often processed into flaxseed oil.

This article tells you everything you need to know about flax seeds.

Flaxseeds have

They consist of 71% fat, 21% carbs, and 14% protein.

One tablespoon (10 grams) of whole flax seeds provides the following nutrients:

• Calories: 55
• Water: 7%
• Protein: 1.9 grams
• Carbs: 3 grams
• Sugar: 0.2 grams
• Fiber: 2.8 grams
• Fat: 4.3 grams

Carbs and fiber

Flax seeds are made up of 21% carbs — a whopping 95% of which is fiber.

This means that they’re low in net digestible carbs — the number of total carbs minus the amount of fiber — making them a low-carb food.

Two tablespoons (20 grams) of flax seeds provide about 6 grams of fiber. For reference, people should usually eat 14 grams of fiber for every 1000 calories they consume.

• 25% soluble fiber (cellulose, lignin, and hemicellulose)
• 75% insoluble fiber (gums, pectin, and beta-glucan)

Soluble fiber helps regulate blood sugar and cholesterol levels. It also promotes digestive health by feeding your beneficial gut bacteria.

When mixed with water, the mucilage gums in flax seeds become very thick. Combined with the insoluble fiber content, this makes flax seeds a natural laxative.

Consuming flax seeds can help promote regularity, prevent constipation, and reduce your risk of diabetes. The soluble fiber in flax seeds can lower LDL cholesterol, which decreases your risk of cardiovascular disease.

Protein

Despite containing essential amino acids, they’re low in the amino acid lysine that’s needed for human protein synthesis.

Therefore, they’re considered an incomplete protein.

Still, flax seeds are high in the amino acids arginine and glutamine — both of which are important for heart and immune system health.

Fat

Flax seeds contain 71% fat, with 1 tablespoon (10.3 grams) providing

This fat content in 100 grams of flax seeds is composed of:

• 3.66 grams saturated fatty acids
• 7.53 grams of monounsaturated fatty acids
• 28.7 grams of polyunsaturated fatty acids

Flax seeds are one of the richest dietary sources of ALA. In fact, they’re only exceeded by chia seeds.

ALA is an essential fatty acid, which means that your body cannot produce it. Thus, you need to obtain it from the food you eat.

Flaxseed oil contains the highest amount of ALA, followed by milled seeds. Eating the seeds whole provides the least amount of ALA, as the oil is locked up inside the fibrous structure of the seed.

Flax seeds have a high content of omega-3 fatty acids, but they don’t contain as much omega-3 as fish oils. Omega-3 can have a wide range of health benefits, including:

• reducing cardiovascular disease risks
• improving eye and brain health
• reducing risks of inflammatory conditions like arthritis and asthma

Fatty fish and fish oil contain the active forms of omega-3s, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), whereas the ALA in flax needs to be converted into these forms after ingestion.

Flax seeds are a good source of several vitamins and minerals:

• Thiamine. This B vitamin is also known as vitamin B1. It’s essential for normal metabolism and nerve function.
• Copper. An essential mineral, copper is important for energy production and iron metabolism, and it also acts as an antioxidant and supports the immune system.
• Magnesium. An important mineral that has many functions in your body, magnesium is occurs in high amounts in grains, seeds, nuts, and green leafy vegetables.
• Phosphorus. This mineral is usually found in protein-rich foods and contributes to bone health and tissue maintenance.

• p-Coumaric acid. This polyphenol is one of the main antioxidants in flax seeds.
• Ferulic acid. This antioxidant may help prevent several chronic diseases.
• Phytosterols. Related to cholesterol, phytosterols are found in the cell membranes of plants. They have been shown to have cholesterol-lowering effects.
• Lignans. Lignans are present in almost all plants, acting as both antioxidants and phytoestrogens. Flax seeds are exceptionally rich in lignans, containing up to 800 times more than other foods.

Brown flax seeds have slightly higher antioxidant activity than yellow varieties.

Lignans

Flax seeds are rich dietary sources of lignans. These nutrients function as phytoestrogens.

Phytoestrogens are plant compounds that are similar to the female sex hormone estrogen. They have weak estrogenic and antioxidant properties.

Lignans are fermented by bacteria in your digestive system and may reduce the growth of several cancers — especially hormone-sensitive types, such as breast, uterus, and prostate cancer.

Flax seeds may be useful as a part of a weight loss diet.

They contain soluble fiber, which becomes highly sticky when mixed with water.

This fiber has been shown to be effective at suppressing hunger and cravings, potentially promoting weight loss.

However, more

Flax seeds have been associated with major benefits for heart health, mainly attributed to their content of omega-3 fatty acids, lignans, and fiber.

Blood cholesterol

Blood cholesterol levels are a well-known risk factor for heart disease. This is especially true for high levels of oxidized LDL (bad) cholesterol.

One study noted that daily consumption of milled flax may lower cholesterol by 11% in the short-term.

These studies also indicate a 15% reduction in the number of LDL (bad) cholesterol particles.

This is supported by animal studies showing that flax seeds may improve cholesterol levels and the composition of blood fats.

These seeds may be very useful when consumed along with cholesterol-lowering medication.

This cholesterol-lowering effect is thought to be caused by the high fiber, protein, and lignan content in flax seeds.

Omega-3 fatty acids

Omega-3 fatty acids are essential. They may have

Flax seeds are very high in the omega-3 fatty acid alpha-linolenic acid (ALA).

Plant-based ALA fatty acids seem to benefit heart health similarly to fish oils, which are rich in EPA and DHA.

Blood pressure

Eating flax seeds is an effective way to lower blood pressure.

A randomized, double-blind trial in patients with peripheral arterial disease found that consuming 30 grams of milled flaxseed daily for six months significantly reduced both systolic and diastolic blood pressure.

On average, systolic blood pressure dropped by about 10 mm Hg, with effects appearing within one month and lasting up to a year.

Overall, more participants in the flaxseed group experienced blood pressure reductions compared to the placebo group, suggesting a meaningful cardiovascular benefit.

Flax seeds have been shown to benefit many aspects of human health.

Digestive health

Diarrhea and constipation cause major distress and may even threaten your health.

Lots of research has found that flax seeds prevent both diarrhea and constipation.

The insoluble fiber content in flax seeds adds bulk to your digestive waste, acting as a laxative and relieving constipation.

Soluble fiber is also thought to bind to water in your digestive tract. This causes it to swell and increase the bulk of your stool, preventing diarrhea.

Diabetes

A

However, it showed no consistent effects on fasting glucose, body weight, blood pressure, insulin resistance, or most lipid measures overall.

Some subgroup analyses suggested benefits for cholesterol and fasting glucose in specific higher-risk groups, but results were mixed and need further confirmation.

Though the link between flax seeds and type 2 diabetes is still unclear, they may be considered a safe and healthy addition to your diet if you have type 2 diabetes.

Cancer

Flax seeds may suppress the formation of several types of cancer, such as those of the colon, breast, skin, and lungs.

One study concludes that flaxseed contains bioactive compounds (such as lignans and omega-3s) that have potential anticancer effects, including reducing tumor growth and influencing cancer-related pathways.

However, most evidence is preclinical or limited, so while flaxseed may help prevent cancer, stronger human studies are still needed to confirm its effectiveness.

Dry flax seeds are usually well tolerated, and allergy is rare.

Still, it’s recommended to drink plenty of water when eating these seeds.

Cyanogenic glycosides

Flax seeds naturally contain plant compounds called cyanogenic glycosides. These substances can bind with sulfur compounds in your body to form thiocyanates.

One study notes that flaxseed contains compounds like cyanogenic glycosides that can release hydrogen cyanide, posing a theoretical toxicity risk, but typical dietary amounts produce levels far below those needed to cause harm.

Overall, it concludes that no clinically significant toxicity has been observed in humans, and harmful effects would require unrealistically high intake levels.

Phytic acid

Similar to other seeds, flax seeds contain phytic acid.

Phytic acid is often referred to as an antinutrient, as it may reduce the absorption of minerals like iron and zinc.

Still, phytic acid doesn’t cause any lasting reduction in mineral absorption and does not affect any subsequent meals.

Therefore, this should not be a major concern — except for people who are deficient in minerals like iron and/or follow an imbalanced diet.

Digestive problems

For people who are not used to eating a lot of fiber, incorporating flax seeds too quickly can cause mild digestive problems. These

It’s best to start with small doses and work your way up to 1–2 tablespoons (10–20 grams) daily.

Adding flax seeds to your diet may also increase bowel movement frequency, as flax seeds are a natural laxative.

Risks during pregnancy

Though human studies are limited, some health professionals

This is due to the phytoestrogens in the seeds, which may act similarly to the female sex hormone estrogen.

Animal studies show that flax seeds and flaxseed lignans may cause lower birth weight and affect the development of the offspring’s reproductive system — especially if consumed during early pregnancy.

It’s unlikely that smaller doses of flax seeds will have an adverse effect.

Blood-thinning effects

Large doses of omega-3 fatty acids may have blood-thinning effects.

If you have a bleeding disorder or are taking blood thinners or other medications, consult with your healthcare professional before incorporating large amounts of flax seeds into your diet.

Flax seeds have become popular due to their high content of omega-3 fatty acids, fiber, and other plant compounds, which are responsible for many of the seeds’ benefits.

They may have positive effects on improving digestive health and reducing the risk of heart disease and cancer.