Evidence Based
4.1 /5
13

15 Flaxseed Oil Benefits + Side Effects & Caveats

Written by Puya Yazdi, MD | Last updated:
Jonathan Ritter
Medically reviewed by
Jonathan Ritter, PharmD, PhD (Pharmacology) | Written by Puya Yazdi, MD | Last updated:

SelfHacked has the strictest sourcing guidelines in the health industry and we almost exclusively link to medically peer-reviewed studies, usually on PubMed. We believe that the most accurate information is found directly in the scientific source.

We are dedicated to providing the most scientifically valid, unbiased, and comprehensive information on any given topic.

Our team comprises of trained MDs, PhDs, pharmacists, qualified scientists, and certified health and wellness specialists.

All of our content is written by scientists and people with a strong science background.

Our science team is put through the strictest vetting process in the health industry and we often reject applicants who have written articles for many of the largest health websites that are deemed trustworthy. Our science team must pass long technical science tests, difficult logical reasoning and reading comprehension tests. They are continually monitored by our internal peer-review process and if we see anyone making material science errors, we don't let them write for us again.

Our goal is to not have a single piece of inaccurate information on this website. If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please leave a comment or contact us at [email protected]

Note that each number in parentheses [1, 2, 3, etc.] is a clickable link to peer-reviewed scientific studies. A plus sign next to the number “[1+, 2+, etc...]” means that the information is found within the full scientific study rather than the abstract.

Flaxseed oil is one of the best plant sources of omega-3 fatty acids. It may improve heart, skin, gut, and brain health, though much more research is required. How might it work, and how good is the evidence? Find out here.

What Is Flaxseed Oil?

Flaxseed oil is pressed from flaxseed. It contains 50 to 60% omega-3 fatty acids (mainly alpha-linolenic acid) and lignans [1, 2, 3].

For many centuries, people used flaxseed for its laxative properties. It is also used in bakery products, and its fibers are spun to make linen [4].

Constituents

Flaxseed oil contains many active compounds, including [4]:

  • Omega-3 fatty acids (alpha-linolenic acids)
  • Proteins help decrease heart disease risk factors
  • Fibers help prevent constipation
  • Phenolic compounds (lignans) help protect against cancer
  • Minerals (calcium, magnesium, and phosphorus)

Mechanisms

The alpha-linolenic acid (ALA) from flaxseed oil is converted in the body into the unsaturated fatty acids, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) [5].

These unsaturated fatty acids are then converted to lipids (fats). The fat molecules promote eye health as well as brain and nervous system development. They also reduce the risk of high blood pressure, high cholesterol, and cancer, improve memory, and slow aging and risk of coronary disease [5].

Eating flaxseed in both ground and oil forms increase blood ALA. However, consuming flaxseed oil rather than ground flaxseed results in significantly higher ALA levels in the blood [6].

Potential Health Benefits (Possibly Effective)

The potential benefits discussed in this section have at least one human trial to back them up, but either the results haven’t been repeated or the evidence has been contradictory. Much more research is required to determine whether flaxseed oil is effective for any of these purposes, and better alternatives are available.

It’s important to note that the FDA has not approved any flaxseed product for any medical purpose or health claim. Flaxseed is a safe component of many foods, but we still recommend talking to your doctor before using it as a supplement.

1) Heart

In a study of 56 participants, a 3-gram daily supplementation of ALA (from flaxseed oil supplements) increased blood EPA levels. These levels grew 60% after 12 weeks in comparison to the placebo group, which showed no EPA increase [7].

In the human body, ALA from flaxseed oil is partially metabolized into EPA and DHA. The FDA has recently approved health claims that omega-3 fatty acids (EPA and DHA specifically) may reduce the risk of high blood pressure and heart disease [8, 1, 9].

Cholesterol

In a review of 28 studies, the authors suggested that flaxseed oil slightly lowers the amount of total and LDL (bad) cholesterol in the blood. However, the amplitude of the effect was dependent on the sex and health status of participants [10].

12 months of high flaxseed diets also lowered LDL and total cholesterol in 110 heart disease patients. However, the degree to which flaxseed’s oil was responsible is unclear [11].

In hamsters, flaxseed, but not flaxseed oil, prevented cholesterol increases, casting some doubt on whether the oil alone could be useful [12].

The best results for cholesterol in both animals and humans have been achieved with ground flaxseed or flaxseed extract, not flaxseed oil. This suggests that non-fatty flaxseed compounds (for example, its fibers) could be responsible for this potential benefit. Additional human studies will be required to clarify.

2) Skin Health

Dietary ALA deficiency is associated with dry and uncomfortable skin and poor skin quality in humans. Flaxseed oil is rich in ALA and improved skin sensitivity and hydration in a study of 13 women [13, 14].

In another study of 45 women, flaxseed oil ingestion for 12 weeks reduced skin redness and roughness [15].

Eczema is a common skin disorder with dry, uncomfortable, and red skin. Flaxseed oil lowered saturated fatty acid levels in both horses and human skin cells, which may reduce rash areas and help clear irregular skin [16, 17].

Flaxseed oil has a high ALA content, which decreased skin cell inflammation and promoted regenerative functions in a cell study [17].

Flaxseed also lowered skin cell inflammation and increased repair in skin cells [17].

3) Gut Health

Flaxseed oil is believed to help with constipation [18, 19].

In a study of 50 patients, daily supplementation with 4 mL of flaxseed oil helped relieve constipation [20].

Flaxseed oil also relieved Irritable Bowel Syndrome (IBS) symptoms by lowering inflammation in a pilot study of 40 IBS patients [21].

It is currently unclear which components of flaxseed might be responsible for these effects. Further human trials are needed.

4) Brain Health

In a study of 30 healthy adults, ALA supplementation increased BDNF levels. BDNF is a vital growth factor for neurons; the authors of this study concluded that ALA is worth studying in the context of stroke recovery [22].

In a study of 51 bipolar disorder patients, flaxseed oil supplementation helped improve their mood [23].

Daily flaxseed oil consumption helped prevent diabetes-related brain dysfunction in diabetic rats. Flaxseed oil stopped oxidative stress, thus protecting brain cells [24].

In rats, pretreatment with flaxseed oil protected against seizures. It helped reduce convulsion time [25].

Flaxseed oil supplementation significantly reduced lead and nitric oxide levels in rat brains. This helps prevent free radical formation and stops oxidative damage [26].

As with many of the potential benefits of flaxseed oil, many more human trials are required.

Other Potential Benefits with Insufficient Evidence

5) Blood Sugar

Individuals with PCOS tend to have high insulin and glucose levels and may be at higher risk of diabetes. In a study of 60 women with PCOS, flaxseed oil supplementation had beneficial effects on insulin metabolism [27].

In diabetic rats, daily flaxseed oil consumption prevented diabetes-related brain dysfunction. Flaxseed oil stopped oxidative stress and improved neurotransmitter levels, thus protecting brain cells [24].

However, in a study of 90 prediabetic individuals, flaxseed powder had no effect on their glucose levels or insulin resistance. These mixed results indicate the need for further human studies on the various components of flaxseed (powder vs. oil vs. extract, etc.) in people with specific health conditions [28].

6) Inflammation

In a study of 100 patients with carpal tunnel syndrome, the patients reported an improvement in their symptoms after topical flaxseed oil application. They had reduced inflammation and pain after a month of oil application [29].

In rats, flaxseed oil injections under the skin helped reduce inflammation by preventing the widening of blood vessels. It also decreased inflammatory markers (histamine, bradykinin, prostaglandin E2, and leukotriene B4) [30].

7) ADHD

In a pilot study of 30 children with ADHD, supplementation with flaxseed oil and vitamin C improved their ADHD symptoms and increased their EPA and DHA levels. The children had improved restlessness, inattention, self-control, and impulsiveness [31].

8) Menopause

In a study of 140 menopausal women, flaxseed oil supplementation improved their menopause symptoms. The women reported less hot flashes and an increase in quality of life [32].

9) Carpal Tunnel

In a study of 100 patients with carpal tunnel (many in both hands), topical application of flaxseed oil significantly reduced reported symptoms and improved joint function [29].

10) Diabetic Ulcers

In a study of 60 patients with diabetic foot ulcers, 2 g of flaxseed oil per day (in addition to conventional antibiotics) improved speed and quality of healing compared to conventional treatment alone [33].

11) Sjogren’s Syndrome Symptoms

Sjogren’s syndrome is an immune system disorder with uncomfortable symptoms of dry eyes and a dry mouth.

Taking daily 1 or 2 g flaxseed oil supplements significantly reduced eye inflammation and helped with dry eye symptoms in a study (RCT) of 38 Sjogren’s syndrome patients. Flaxseed greatly increased eye comfort and health [34].

Animal Studies (Lacking Evidence)

No clinical evidence supports the use of flaxseed or flaxseed oil for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies listed below should not be interpreted as supportive of any health benefit.

12) Bone Health

Diets deficient in ALA have been associated with increased bone resorption and osteoporosis in humans. Since flaxseed is one of the best sources of dietary ALA, some researchers have suggested that flaxseed could help maintain bone health [35].

In mice that consumed a diet high in flaxseed oil, the oil appeared to help maintain bone strength. It prevented bone loss caused by drug treatment for IBD [36].

Flaxseed oil consumption also prevented osteoporosis in mice deficient in estrogen [37, 38].

13) Weight Management

Leptin is a protein that is produced by fatty tissue in the body. Low leptin signaling results in overeating. Over time, this can lead to becoming overweight or obese [39].

Flaxseed oil works as a natural laxative and also lowers levels of inflammation, which aids weight loss. Eating flaxseed products induced leptin production in rabbits [40, 41].

The increase in leptin production helped support fat loss and reduced fat buildup in rabbits’ arteries [40].

14) Kidney Health

In a rat model of kidney dysfunction, both flaxseed oil and ground flaxseed supplementation helped prevent the decline in kidney function. However, the ground flaxseed was more effective at protecting against kidney injuries than the oil [42].

Flaxseed oil diets also helped reduce polycystic kidney damage in male and female rats, although it was more effective in female rats. A combination of flax oil and one of its antioxidants (SDG) prevented excess protein in their urine, cystic change, and inflammation in both genders. However, females also had less oxidative damage [43].

Additionally, high blood pressure can damage the kidneys. In rats with high blood pressure, flaxseed oil-supplemented diets helped lower blood pressure and markers of kidney damage (creatinine, blood urea nitrogen, renin, and uric acid) [44].

Cancer Research

Both flaxseed and flaxseed oil contain linoorbitides, a family of compounds that have possible cancer-fighting and antioxidant activities. This compound family increases the shelf-life stability of flaxseed oil in storage. It likely does the same within the human body, providing strong antioxidant properties that lower the rate of tumor cell growth [45].

Flaxseed oil is also a rich source of dietary lignans, which reduce breast cancer risk and lung cancer cell growth [46, 47].

Alpha-linolenic acid slows the growth of cancer cells and kills cancer cells [48, 49].

In mice, flaxseed oil supplementation reduced lung tumor formation and prevented breast cancer cell formation [50, 51, 52].

Though flaxseed oil contains a compound that prevents cancer, the quantity, and frequency necessary to achieve the desired blood concentration may not make it a useful therapy in cancer treatment [53].

Side Effects & Precautions

Higher omega-3 fatty acids levels are associated with a slightly longer bleeding time and slower clotting time. However, there are no cases of bleeding problems documented, even at high levels of omega-3 and when taken with blood-thinning medications [54].

When first taking flaxseed oil, some adults who took more than 6 grams per day experienced stomach and intestinal discomfort [6].

Additionally, some people may be allergic to flaxseed [55].

Flaxseed contains small quantities of cyanogenic glycosides. In typical dietary amounts, however, flaxseed will not produce enough thiocyanate (a precursor to cyanide) to be dangerous [4].

Gene Interactions

In a study of 60 diabetic patients with heart disease, 12 weeks of flaxseed oil supplementation increased the expression of genes related to insulin, inflammation, and fat. It increased PPAR-α levels, which helps with insulin and fat metabolism and maintains fat and glucose balance [56].

Meanwhile, it reduced inflammation and heart disease risk by decreasing the gene production levels of [56]:

In diabetic rats, a diet high in flaxseed oil significantly increased PPAR-α levels. This helps maintain carbohydrate and fat balances. On the other hand, it reduced SREBP-1, which reduces the rats’ fat levels [57].

In diabetic rats, flaxseed oil also decreased the production of the following inflammatory genes [58]:

Limitations and Caveats

Although many animal studies have been performed, there are limited human studies of flaxseed oil. Thus, it is recommended that you consult with a doctor before taking flaxseed oil supplements for their health benefits.

Do not take flaxseed oil if it is rancid or expired, as it can potentially become toxic.

Supplementing with Flaxseed Oil

Dosage

There is no safe and effective dosage of flaxseed oil for any health claim or medical condition, because no sufficiently powered clinical trial has been conducted to find one. That being said, flaxseed and its oil are considered safe for consumption as food, and clinical trials have produced positive results with few side effects.

The recommended daily amount of alpha-linolenic acid from the diet/supplementation is 1.1 – 2.2 grams per day [59, 60].

However, a medical professional may recommend higher amounts in some cases. If you have a specific health concern or disorder, talk to your doctor before taking flaxseed oil [59, 60].

Sources

  • Ground seeds/powder [1]
  • Oil [1]
  • Supplement capsules [1]
  • Topical Gel [61]

Flaxseed Oil vs. Fish Oil

Both flaxseed oil and fish oil are rich sources of omega-3 fatty acids. Fish oil has EPA and DHA directly to the blood and body. Flaxseed oil has ALA, which is then changed into EPA and DHA within the body [62, 63].

However, for vegetarian or vegan people, flaxseed oil could be a way to meet omega-3 daily needs and receive the positive effects of omega-3 fatty acids and lignans.

Buy Flaxseed Oil and Softgels

This section contains sponsored links, which means that we may receive a small percentage of profit from your purchase, while the price remains the same to you. The proceeds from your purchase support our research and work. Thank you for your support.

About the Author

Puya Yazdi

Puya Yazdi

MD
Dr. Puya Yazdi is a physician-scientist with 14+ years of experience in clinical medicine, life sciences, biotechnology, and nutraceuticals.
As a physician-scientist with expertise in genomics, biotechnology, and nutraceuticals, he has made it his mission to bring precision medicine to the bedside and help transform healthcare in the 21st century.He received his undergraduate education at the University of California at Irvine, a Medical Doctorate from the University of Southern California, and was a Resident Physician at Stanford University. He then proceeded to serve as a Clinical Fellow of The California Institute of Regenerative Medicine at The University of California at Irvine, where he conducted research of stem cells, epigenetics, and genomics. He was also a Medical Director for Cyvex Nutrition before serving as president of Systomic Health, a biotechnology consulting agency, where he served as an expert on genomics and other high-throughput technologies. His previous clients include Allergan, Caladrius Biosciences, and Omega Protein. He has a history of peer-reviewed publications, intellectual property discoveries (patents, etc.), clinical trial design, and a thorough knowledge of the regulatory landscape in biotechnology.He is leading our entire scientific and medical team in order to ensure accuracy and scientific validity of our content and products.

Click here to subscribe

RATE THIS ARTICLE

1 Star2 Stars3 Stars4 Stars5 Stars
(78 votes, average: 4.06 out of 5)
Loading...

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.