Can Flaxseed Oil Upset My Stomach?

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Flaxseed oil is naturally derived from the seed of the flax plant. Flaxseed oil is an excellent source of omega-3 fatty acids, especially alpha-linolenic acid, and is comparable to fish oil in terms of health benefits. Due to the anti-inflammatory properties of omega-3 fatty acids, some people take flaxseed oil for stomach irritation and to enhance digestion, although in large quantities it may lead to stomach upset. Eating too much flaxseed, which is rich in fiber, is a more likely cause of gastrointestinal upset. Consult with your doctor if you have a chronically upset stomach.

Flaxseed Oil

According to the University of Maryland Medical Center, flaxseed oil contains between 50 and 60 percent omega-3 fatty acids in the form of alpha-linolenic acid, or ALA. Your body doesn’t convert ALA into useful fats as easily as it does EPA and DHA, which are the omega-3 fatty acids found in fish oil, so flaxseed oil may not have the same health benefits as fish oil, but they are comparable. Benefits of consuming foods rich in omega-3 fatty acids include reduced inflammatory response and reduced risk of blood clots.

Forms of Flaxseed Oil

Flaxseed oil is available as a liquid, which is taken orally, or in capsule form. Good quality flaxseed oil is made using fresh pressed seeds, and then it is processed at low temperatures without light, extreme heat or oxygen because it is easily destroyed within these conditions, according to the “Dictionary of Food Science and Technology.” As such, flaxseed oil is bottled in dark glass containers and is susceptible to quickly turning rancid without refrigeration. Flaxseed oil should be consumed cold and should never be heated or used for cooking.

Flaxseed Oil and Stomach Upset

Taking too much of anything, regardless of health benefits, can cause stomach upset, and flaxseed oil is no exception. As such, ingesting excessive amounts of flaxseed oil may cause an upset stomach, nausea and diarrhea in some individuals. Recommended dosages range from 1 tsp. daily to 1 tbsp. three times daily, but stomach upset can be triggered by just the thought of some foods, so start with small doses of flaxseed oil to begin with. Further, avoid taking flaxseed oil if you are allergic to flaxseed or linseeds, as allergic reactions can include gastrointestinal upset. Finally, make sure your flaxseed is not rancid, since ingesting rancid oil can cause stomach upset and vomiting.

Problems with Ground Flaxseed

Ground flaxseed, but not flaxseed oil, contains a fibrous compound called lignan. According to, consuming large amounts of ground flaxseed has a laxative effect and may cause diarrhea, an increased number of bowel movements and abdominal discomfort. Further, eating large amounts of flaxseed without adequate hydration may cause severe constipation because of the absorptive affect of lignan. Consuming flaxseed oil does not have these same problems.