Common Names: flaxseed, flax, linseed

Latin Names: Linum usitatissimum

Background

• Flaxseed has had a variety of health and industrial uses. Hippocrates wrote about flaxseed being a laxative; North American pioneers made flaxseed dressings for cuts and burns. Fiber from the plant is made into linen, and oil from its seeds is used in paints, among other products.
• Today, flaxseed and flaxseed oil are promoted for a variety of disorders that include stomach and intestinal complaints, such as constipation, diarrhea, and irritable bowel syndrome (IBS). Flaxseed and flaxseed oil are also promoted for heart and blood vessel disorders (for example, high levels of blood fats such as cholesterol and triglycerides), as well as diabetes and other conditions.

How Much Do We Know?

• A number of studies in people have investigated the health effects of flaxseed and flaxseed oil, particularly how flaxseed may affect heart and blood vessel diseases, type 2 diabetes, and menopausal symptoms.

What Have We Learned?

• Flaxseed contains fiber, which may relieve constipation. However, there’s little research on the effectiveness of flaxseed for this condition.
• Authors of a 2019 review article suggest that flaxseed may be helpful for some people diagnosed with heart and blood vessel diseases. (It is not known whether flaxseed oil might have a similar effect.)
• Research suggests that flaxseed may help with blood sugar levels in some people with type 2 diabetes. (It is not known whether flaxseed oil might have a similar effect.)
• Studies have had conflicting results on whether flaxseed helps with symptoms of menopause.
• NCCIH is funding preliminary research on the potential role of flaxseed in inflammation and its effects on the gut microbiome.

What Do We Know About Safety?

• Don’t eat raw or unripe flaxseeds, which may contain potentially toxic compounds.
• Flaxseed and flaxseed oil supplements seem to be well tolerated in limited amounts. Few side effects have been reported.
• Flaxseed may be unsafe during pregnancy as it may have mild hormonal effects, but there is no reliable research on flaxseed’s effects on pregnancy outcomes. Some research suggests that flaxseed oil taken in the second or third trimester of pregnancy may increase the chance of premature births. Little is known about whether it’s safe to use flaxseed while breastfeeding.
• Flaxseed, like any fiber supplement, should be taken with plenty of water, as it could worsen constipation or, in rare cases, cause an intestinal blockage. Both flaxseed and flaxseed oil can cause diarrhea.

Keep in Mind

• Take charge of your health—talk with your health care providers about any complementary health approaches you use. Together, you can make shared, well-informed decisions.

Flax is an annual plant, and it is grown both for its fiber and for its seeds. The ancient Egyptians were probably the first to use flax. They used fiber from the plant to make clothes, fishnets and other products, and they used flaxseed or linseed as food and medicine. Historically, flaxseed is primarily used as a laxative, because it is high in fiber and a gummy material called mucilage. These substances expend when they come in contact with water, so they add bulk to stool and help it move more quickly through the body.

Flaxseed is rich in nutrients. One hundred grams of ground flaxseed supply approximately 450 kilocalories, 41 grams of fat, 28 grams of fiber and 20 grams of protein. Flaxseed oil or linseed oil is rich in alpha-linolenic acid, an omega-3 fatty acid. Omega-3 fatty acids are "good" fats that may be good for heart disease, inflammatory bowel disease, arthritis and other health problems. Each tablespoon of ground flaxseed contains about 1.8 grams of omega-3 fatty acids. Studies suggest that consumption of flaxseed may be beneficial in improving cardiovascular health.

People who eat a Mediterranean diet tend to have higher HDL ("good") cholesterol levels. The Mediterranean diet has a healthy balance of dietary fatty acids including omega-3 fatty acids. It includes whole grains, green vegetables and fruits, fish and poultry, olive, canola and flaxseed oils, and walnuts. The Mediterranean diet limits the amount of red meat, butter, and cream. In laboratory studies, flaxseed and flaxseed oil have been showed to lower cholesterols in animal studies.

One of the best ways to prevent heart disease is to eat a low-fat diet, avoiding foods rich in saturated fats and trans-fats and eating those that are rich in unsaturated fats, for example, omega-3 fatty acids from flaxseed. Evidence suggests that people who eat an alpha-linolenic acid-rich diet are less likely to have a fatal heart attack. A diet rich in fruits, vegetables, whole grains, nuts or legumes, and omega-3 fatty acid rich foods may reduce the risk of heart attack and stroke, both as first-time events and after the first heart attack or stroke. Furthermore, several human studies show that diets rich in omega-3 fatty acids (including alpha-linolenic acid) may lower blood pressure in people with hypertension.

In addition to the important omega-3 fatty acids, flaxseed also contains a group of bioactive components called lignans. Emerging evidence suggests that lignans may help protect body from cancer. In a human clinical study, ate a muffin containing 25 grams of flaxseed for 40 days showed the potential to reduce tumor growth in postmenopausal women who were newly diagnosed with breast cancer. Laboratory studies reported that flaxseed or its bioactive components lignans reduced breast tumor growth and spread in laboratory rodents. Evidence also suggests that flaxseed may benefits men at risk for prostate cancer. In one study, ate a low-fat diet with 30 grams of flaxseed daily lowered prostate specific antigen levels (a marker of prostate health) in men with a precancerous prostate condition called prostatic intraepithelial neoplasia. However, more clinical studies are needed to understand how flaxseed and lignans may affect cancer in humans.

The optimum of intake to obtain health benefits is not known. However, one to two tablespoons of ground flaxseed a day is currently suggested. Flaxseed, when eaten whole, is more likely to pass through the body undigested, which means the body does not get all of the nutrients and bioactive components. The best is to buy the whole flaxseed, as the outside shell in whole seed appears to keep the fatty acids inside well protected, and grind it ourselves at the time we need. A small electric coffee grander seems to work the best. The best place to store ground flaxseed is the freezer, which will keep the ground seed from oxidizing and losing its nutritional potency. Flaxseed comes in two basic varieties: golden and brown. Golden seed is eyes friendly, but there is very little difference nutritionally between the two.

Eating flaxseed is easy. Top a salad with some ground flaxseed, sprinkle it on top of yogurt, smoothies or cereal, or stir a teaspoon into our soup. It also can be a substitute for a tablespoon or two of the flour when we are making breads, cookies, or muffins. Flaxseed oil works best in cold foods like salad dressings and should not be used for frying because it burns easily.

The whole-grain flaxseed muffins are ideal for a snack or a well-rounded breakfast. Below is a recipe of banana flaxseed muffins that we may try and enjoy at our home.

Canola oil spray
1/2 cup plus 3 Tbsp. of whole-wheat flour
1 cup all-purpose flour
1/2 cup plus 1 Tbsp. ground flaxseed
3/4 cup "old-fashioned" oatmeal
1/2 cup brown sugar, packed
2 tsp. baking soda
1 tsp. baking powder
1/4 tsp. salt
2 tsp. ground cinnamon
1 tsp. ground ginger
1-1/2 cups shredded carrots
1/2 cup raisins
1 medium banana, mashed
3 eggs
1 cup skim milk
1 Tbsp. lemon juice
2 Tbsp. unsweetened applesauce
2 Tbsp. canola oil
1 tsp. vanilla

Preheat oven to 350F. Coat muffin tins lightly with canola oil spray and set aside. In large bowl, mix flours, flaxseed, oatmeal, brown sugar, baking soda, baking powder, salt, cinnamon and ginger. Stir in carrots, raisins and banana. In separate bowl, combine eggs, milk, lemon juice, applesauce, canola oil and vanilla. Add liquids to dry ingredients and stir until moist. Pour batter in tins, filling each cup 1/2-3/4 full. Bake for 25 minutes, or until golden brown. Makes 18 muffins.