The Dangers of High Lignan Flax Oil

Flaxseeds are nutrient-rich seeds that contain various vitamins, minerals, antioxidants and lignans. Like most other nutrients, lignans aren't retained in flaxseed oil and have to be added back as a powder. While lignan benefits are numerous, they haven't been well studied.

Flaxseed, also known as linseed or Linum usitassimum, is a nutty, nutrient-rich seed. This seed is sold whole, as a meal or powder, and as an oil. Most of the nutrients in flaxseed are found in whole or ground seeds. Certain micronutrients, like lignans, can be added back into the oil.

Flaxseed is known for being a food that's extremely rich in lignans, with 75 to 800 times more than other plant-based foods. Lignans are a type of phytoestrogen that may help reduce the risk of diseases like cancers, heart disease and osteoporosis.

Oil-based flaxseed products are best suited for people who want to supplement their diets with healthy fatty acids. As shown in an April 2015 article in the ​Journal of Food Science and Technology​, 71.8 percent of the fats in flaxseeds are healthy, polyunsaturated fats like omega fatty acids. Just 18.5 percent of the remaining fats are monounsaturated, while 10 percent are saturated.

Flaxseed oil benefits your health primarily because of two specific polyunsaturated fats: alpha-linolenic and linoleic acid. According to Harvard Health Publishing, both of these are essential fats that you can only obtain from your diet. Flaxseed is particularly unique, because it's hard to find plant-based foods that are rich in alpha-linolenic acid (ALA).

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There are several types of lignans in flaxseed, but the main type is known as secoisolariciresinol diglycoside (SGD). The bacteria in your gut microbiome metabolize lignans like SGD and releases them into your bloodstream. Once they're in your bloodstream, lignans move throughout your body, where they are thought to provide you with a variety of benefits.

According to the ​Journal of Food Science and Technology​ article, lignans are able to act as antioxidants, scavenging harmful free radicals and preventing cancer. Lignans are also thought to help reduce the risk of a variety of other conditions, including high cholesterol, high blood pressure, atherosclerosis, diabetes and liver disease.

These claims are supported by various recent studies, like an April 2013 study in the journal ​Cancer Causes and Control​, which showed how the lignans in flaxseed significantly reduced the risk of breast cancer. A May 2014 study in the ​Diabetes Care Journal​ also discussed how lignans can help reduce the risk of diabetes.

However, clinical studies that focus on the lignans' benefits are generally limited. Both a June 2017 review in the ​American Journal of Epidemiology​ and an April 2017 meta-analysis in the ​Molecular Nutrition and Food Research Journal​ agreed that studies on lignans were promising, but found limited evidence on the subject.

It is not yet completely understood how much or which specific lignans are needed to support good health. This ultimately means that while there are no real dangers to consuming high-lignan flax oil, this product may not provide you with any major benefits either.

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Flaxseed oil's most well-established benefits come from its healthy fats. This seed has a lot of ALA compared to linoleic acid. Although linoleic acid is an essential fat, it's an omega-6 rather than an omega-3 fatty acid. Omega-6 fats can be found in a variety of commonly consumed plant-based products, like mustard, soybeans, corn and olive oil. Most people who eat according to Western dietary standards tend to consume too many omega-6 and not enough omega-3 fats.

If you consume too many omega-6 fatty acids, you may increase your risk of various health issues, including inflammatory bowel disease, rheumatoid arthritis and obesity. However, don't misunderstand: Omega-6 fats aren't harmful like saturated fats or trans fats. Omega-6-related issues are often simply resolved by consuming more omega-3 fats.

This is where flaxseed oil's benefits come in: Since flaxseed has a higher than average amount of ALA, it can improve your health by adding more omega-3 fatty acids to your diet. According to a September 2015 review article in the ​BioMed Research International Journal​, ALA also has the ability to protect your heart and brain and reduce inflammation and depression.

Some of the ALA you consume is converted into other omega-3 fatty acids, like docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which have even more health benefits.

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There's not much difference between lignan flax oil and regular flax oil aside from the added lignans. The lignans are found in the carbohydrate portion of the flaxseed and aren't retained when these seeds are used to make oil. Fortunately, lignan bioavailability increases when flaxseeds are ground up, making it easy enough to add them back into oils and other products.

However, the beneficial fatty acid content doesn't really change when you add lignans into oil-based products. The finely ground flaxseed particles that have been mixed back into the oil aren't even substantial enough to affect your flax oil's macronutrient content.

For example, 1 tablespoon (15 milliliters) of Barlean's Organic Clear Flax Oil has 120 calories and 14 grams of fat. Out of this fat content, 1 gram is saturated, 9 grams are polyunsaturated and 2.5 grams are monounsaturated. Barlean's even notes the amount of omega fatty acids in each serving. Each tablespoon has:

• 7,640 milligrams of ALA (omega-3)
• 1,900 milligrams of linoleic acid (omega-6)
• 2,200 milligrams of oleic acid (omega-9)

In comparison, each tablespoon (15 milliliters) of Barlean's Organic Lignan Flax Oil has 120 calories and 13 grams of fat. Out of this fat content, 1 gram is saturated, 9 grams are polyunsaturated and 2.5 grams are monounsaturated. With:

• 7,230 milligrams of ALA (omega-3)
• 1,800 milligrams of linoleic acid (omega-6)
• 2,100 milligrams of oleic acid (omega-9)

As you can see, there are fewer healthy fatty acids in lignan flax oil, but this difference is fairly minimal. The Institute of Medicine considers between 1.1 and 1.6 grams of ALA per day to be adequate for adults, so a tablespoon of both regular flax oil or lignan flax oil can provide you with far more than your recommended daily intake of omega-3 fatty acids.

Although both regular flax oil and lignan flax oil are good sources of essential fats, these products are not for everyone. The Mayo Clinic states that flaxseed oil may:

• Decrease blood clotting and increase the risk of bleeding
• Lower blood pressure
• Lower blood sugar levels
• Reduce estrogen levels, decreasing the effectiveness of oral contraceptive drugs and hormone replacement therapy
• Decrease the absorption of drugs that are consumed orally

If you're taking supplements or medications, particularly contraceptives or anti-coagulant, blood pressure or diabetes drugs, you may want to consume flaxseed oil in moderation.

You should also be aware that flaxseed oil is not appropriate for everyone. According to the Academy of Nutrition and Dietetics, ALA may make certain tumors, like prostate cancer tumors, more aggressive. People who have or have had prostate cancer may not want to supplement their diets with ALA-rich fats like flax oil.

However, lignans have been shown to reduce tumor aggressiveness, especially in hormone-related cancers. Given that lignan flax oil reduces the risk of tumor growth and counteracts further spread, this means that it is much more beneficial than regular flax oil.

However, lignan flax oil still has the potential to interact with medications. If you've had or are currently being treated for a hormone-related health problem, you should talk to your doctor before incorporating any type of flaxseed oil into your diet.