Is Flaxseed Oil a Suitable Substitute for Fish Oil?

August 22, 2021

by Cathe Friedrich

Fish oil and flaxseed oil are both a source of omega-3s, a type of polyunsaturated fatty acid. More people are adding omega-3s to their diet, as studies show these healthy fats have anti-inflammatory activity. But if you eat a vegan diet or can’t tolerate fish oil, you might substitute flaxseed oil instead since flaxseed oil is a source of omega-3s too. But you might also wonder if they’re comparable in terms of their health benefits.

Why Omega-3s May Be Beneficial

Research shows that low-grade inflammation is the driving force behind many health problems, including cardiovascular disease. Although studies are mixed, some research suggests that omega-3s may lower the risk of cardiovascular disease. Plus, there’s some evidence that omega-3s are of benefit for people with chronic joint pain due to arthritis.

What about the heart health benefits? Although studies are mixed, research shows fish oil may:

Lower blood pressure
Reduces inflammation
Lower blood triglycerides

These perks are all beneficial for the health of your heart. However, studies looking at the cardiovascular benefits of fish oil are mixed. One study found that supplementing with fish oil didn’t lower the risk of stroke or heart attack in healthy adults, but there seem to be modest benefits for people who don’t eat fish. According to Harvard Health, consuming large quantities of fish oil may modestly boost protection against cardiovascular disease.

How Flaxseed Oil and Fish Oil Differ

With most of the focus being on fish oil, you might wonder how flaxseed oil stacks up. Although fish oil and flaxseed oil both contain omega-3s, the types of omega-3 they contain differ. The type of omega-3 in fish oil is a long-chain omega-3s, a type of fat that lots of research have focused on. These fatty acids are called eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

Not only do long-chain omega-3s in fish oil have anti-inflammatory activity, but they’re integral parts of the membrane that covers cells, including cells in the brain. They help keep the cell membrane more fluid, which is important for optimal function. Cells don’t function as well when their membranes are rigid. So long-chain omega-3s are beneficial for the health of your heart and brain.

Flaxseed Oil Contains Short-Chain Fatty Acids

Unlike fish oil where most of the omega-3s are in the long-chain form, flaxseed oil contains short-chain fatty acids called alpha-linolenic acid (ALA). Your body can convert some ALA from flaxseed oil to the long-chain fatty acids, DHA and EPA, but the process isn’t very efficient. Studies show that less than 5% of the ALA in flaxseed oil is converted to DHA and EPA.

This doesn’t mean that ALA doesn’t have health benefits of its own. It’s an essential fatty acid, one that your body needs and can’t make. Plus, there’s evidence that ALA lowers the risk of cardiovascular disease independent of its conversion to DHA and EPA.

One study found that ALA lowers blood pressure and may also reign in inflammation in the inner walls of arteries, thereby reducing the risk of heart attack and stroke. Still, there isn’t as much research into the health benefits of ALA relative to the long-chain omega-3s in fish oil.

Which Should You Choose?

If you eat a vegan or vegetarian diet, flaxseed oil would be your best option since fish oil comes from fish. Some people also choose flaxseed oil because they’re concerned about the contaminants in fish, including heavy metals. Fish, particularly large fish high on the food chain, can contain toxins, including mercury and polychlorinated biphenyls. (PCBs)

However, most fish oil in supplements is purified via molecular distillation, a process that removes heavy metals and toxins. So, the threat of toxins isn’t high when you take a fish oil supplement. However, do your research and inquire whether the company you purchase from does independent testing to ensure purity.

With the low conversion of ALA to DHA and EPA, you can’t count on getting significant long-chain fatty acids from flaxseed oil. That’s important since DHA and EPA have more research supporting their health benefits. But if you don’t consume animal products, flaxseed oil is an alternative.

What about flaxseed as opposed to oil? The seeds contain lignans, compounds that block the stimulating effects of estrogen on breast tissue. Therefore, they may be beneficial for lowering the risk of breast cancer as they block the effects of stronger estrogens. However, the oil itself does not contain lignans. In addition, the seeds are a good source of fiber, protein, iron, and calcium.

If you add flaxseed to your diet, grind it into a fine powder before consuming it. Unless you do, the seeds will pass through your digestive tract without offering health benefits. You can grind flaxseed in a grinder.

Precautions

Both flaxseed oil and fish oil can interact with some herbs, supplements, and prescriptions, including blood thinners. So, talk to your physician before taking a flaxseed or fish oil supplement. You can also get long-chain omega-3s, including DHA and EPA, by eating fatty fish, like wild-caught salmon and sardines, twice per week. The benefit of this is you’ll also get the vitamins, minerals, and protein from the fish too. If you don’t consume fish, you can also get short-chain omega-3s from sources like walnuts, sesame seeds, hemp seeds, and chia seeds.

References:

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Parikh M, Maddaford TG, Austria JA, Aliani M, Netticadan T, Pierce GN. Dietary Flaxseed as a Strategy for Improving Human Health. Nutrients. 2019;11(5):1171. Published 2019 May 25. doi:10.3390/nu11051171.
“Flaxseed Oil vs. Fish Oil: Which Is Better?.” 13 May. 2020, healthline.com/nutrition/flaxseed-oil-vs-fish-oil.
“Why not flaxseed oil? – Harvard Health.” 29 Jul. 2019, health.harvard.edu/heart-health/why-not-flaxseed-oil.
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