Fish Oil vs. Cod Liver Oil: Which One Should You Actually Take? - Ask a Nutritionist

Transcript:

Alyssa: Hi everyone and welcome back to “Ask a Nutritionist”, our weekly mini episode of Dishing Out Nutrition. I am Alyssa Krejci, Registered Dietitian, with Nutritional Weight & Wellness . Today we're quickly going to dive into the difference between omega-3 fish oil supplements and cod liver oil, and how to know which one you may want to take.

What are omega-3 fats & why might you want to supplement with them?

First, what exactly are omega-3 fats and why would you want to supplement with them? So omega-3 fatty acids are a type of polyunsaturated fat. They are considered essential fatty acids because they are necessary for your health and wellbeing, and they cannot be made by the body on its own. You must get them for the diet, either from food and/or supplements.

These fatty acids play important roles in different body processes affecting inflammation, heart, brain, and eye health. Omega-3 fatty acid deficiency is associated with many health concerns, including heart disease, depression, and arthritis.

There are three main types of omega-threes that we focus on. First is alpha linolenic acid or a ALA. It's the most common omega-3 fatty acid in the diet. It is found mostly in plant foods. Think chia seeds, flax seeds, basil seeds, hemp hearts, and walnuts. ALA is an essential precursor of the other main types of omega-3 fats, EPA and DHA. The conversion process of ALA into EPA and DHA, unfortunately is inefficient in humans.

Only a very small percentage of ALA will be converted into EPA, and even less of it will be converted into DHA. When ALA is not converted into EPA or DHA, it's simply used as energy or stored like other vats in the diet. EPA and DHA are the main omega-3 fats found in seafood, including fatty fish and algae.

They can also be found in meat and dairy from grass fed animals and omega-3 pastured or enriched eggs. EPA and DHA are the forms of omega-3 fatty acids best utilized by the human body and are most associated with the health of your brain, heart, eyes, and for supporting overall inflammation.

If you are eating inadequate amounts of omega-3 rich foods, supplementing with them is often recommended. Most omega-3 fish oil supplements use the EPA and DHA forms from fatty fish, usually anchovies, sardines, mackerel, and herring. They do not naturally contain any meaningful amounts of any vitamins like vitamin D. When you take a standard omega-3 fish oil supplement, you're mainly getting EPA and DHA omega-threes.

More on the health benefits of omega-3 fish oil

Let's talk a bit more about the health benefits of fish oil. So omega-3 fish oil supplements, they're one of the most popular supplements to take for everyday health. Research supports omega-3 supplementation for heart health, supporting lowering triglyceride levels, blood pressure, and just supporting overall cardiovascular health.

For brain and eye health, DHA plays a critical role in brain and eye structure. It's crucial during pregnancy and infancy in brain and eye growth and function. You will often see DHA included in quality prenatal supplements. DHA is the main structural fat in the brain, comprising over 90% of the omega-3 fatty acids. Having low levels of DHA in your brain and our eyes may slow down signaling between cells. The result could be poor eyesight or altered brain function.

EPA has also been studied for its support in with depression and anxiety. For overall inflammation, the body uses EPA to make signaling molecules that have various physiological roles and reduce inflammation. Fish supplementation can help replete levels of omega-threes when the diet isn't adequate. Reducing markers of inflammation, it can be beneficial with conditions like rheumatoid arthritis.

Cod liver oil: what is it & what is it good for?

Now, let's discuss cod liver oil a bit more. So cod liver oil is exactly what it sounds like. It's oil extracted, specifically from the liver of codfish. Liver is rich in fat soluble vitamins like vitamin A and vitamin D. The key difference with cod liver oil, because it comes from the liver, it contains not only omega-3 fatty acids, but it also has significant amounts of fat soluble vitamins, specifically vitamin A and vitamin D.

So cod liver oil gives you EPA and DHA plus vitamin A and vitamin D. That makes cod liver oil more of a combo supplement. Cod liver oil shares many of the same omega-3 benefits as fish oil for heart and brain health, as well as its anti-inflammatory effects, but it also provides vitamin D for supporting immune function, bone health and mood regulation.

If someone is low in vitamin D, cod liver oil can help address that, although we must look at dosing carefully. Cod liver oil also includes vitamin A. Vitamin A has many roles in the body, including supporting your healthy vision, brain function, and skin health. With high levels of vitamin A in cod liver oil, we need to keep in mind the upper tolerable levels of vitamin A. Think about dosing.

For adult men and adult women over 19 years of age, the upper tolerable intake for preformed vitamin A is 3000 micrograms per day. For males and females younger than 19 years of age, the upper tolerable intake will be less, and it'll vary depending on the person's age.

A single teaspoon, for example, or five milliliters of cod liver oil we carry at our offices provides 540 micrograms. The upper tolerable intake levels for infants and children up to age three is only 600 micrograms. Historically, cod liver oil was used to prevent rickets before vitamin D fortification and supplementation became common.

How to choose between omega-3 & cod liver oil

Now let's talk about how to choose between traditional omega-3 fish oil supplements and when you might want to choose cod liver oil. Here's how I guide patients in practice. First, choose fish oil if you're targeting high triglycerides, you're working on lowering inflammation, you want mood support, or you're pregnant or trying to conceive and need controlled DHA dosing.

Maybe you already supplement with vitamin D or you take a multivitamin with vitamin A or you eat liver on a regular basis. Fish oil will allow you to increase omega-3 intake without risking any excessive intake of fat-soluble Vitamin A. Fish oil can be a bit more customizable.

Cod liver oil can be chosen when you don't take a multivitamin with vitamin A and you want a more moderate dose of omega-3. Cod liver oil can also be an option for children since you can take it in smaller doses. Plus it gives a slight boost in vitamin D.

Dose needs to be considered to make sure you're avoiding excessive intake of vitamin A. Although cod liver oil does naturally contain some vitamin D, we generally still recommend adults take a separate vitamin D supplement to get adequate doses of vitamin D to prevent deficiency. Especially if the person is living in a northern climate.

Keep in mind vitamin A, since it's fat soluble, it can be overdone as it can accumulate in the body. Because of this vitamin A content, cod liver oil is not going to be appropriate when you're pregnant, as excess vitamin A can be harmful to a developing fetus;

When you're taking a multivitamin that already contains vitamin A, or when you eat liver on a regular basis. If you fit into one of those categories, fish oil is the safer and more recommended option for supplements.

Dosage recommendations

What about dosage? Always read the label on the back of the bottle. Don't rely on looking at the front and just see a thousand milligrams of fish oil. Turn it around and look at the back. Look for how much EPA plus DHA a supplement contains.

If the supplement doesn't specify the doses of EPA and DHA, you don't really know what you're getting. This is one simple way to differentiate between high quality omega-threes and lower quality, less expensive ones. For daily omega-3 maintenance, we often recommend a dosing of about 2000 to 3000 milligrams total omega-threes with at least 600 milligrams coming from EPA and 400 milligrams coming from DHA or a total of one gram from EPA plus DHA.

If you're wanting extra support for heart health, brain health, or inflammation, we will often do a slightly higher dose, maybe having you benefit from about 900 milligrams from EPA and 600 milligrams from DHA.

No matter which one you choose, a quality supplement is critical. Look for third party testing, sustainable sourcing, and no rancid smell, as a rancid odor can mean it's been oxidized, and rancid fish oil is inflammatory. It's the opposite of what we want. If it has a strong, unpleasant, fishy smell, it's a sign that it’s probably gone bad. A slight fish smell is actually normal with omega-3 supplements.

Can you get enough omega-3 by eating fish alone?

You may be wondering, can I just eat fish instead of needing a supplement? Yes, of course. And ideally, that's how we get adequate omega-threes is through fish, through food, in our diet. We recommend enjoying at least three servings of fatty fish per week.

What counts as fatty fish? Think of the acronym SMASH. SMASH is an acronym for the five types of small cold water fish that are high in omega-3 fatty acids. The SMASH fish include salmon, mackerel, anchovies, sardines, and herring.

The trouble is most of us don't get enough omega-3 rich foods through diet alone, and that's where supplementing is very helpful if you're not eating fatty fish several times per week and or you need therapeutic doses for specific health conditions. Food first, supplement second as needed. Omega-3 fish oils are a case where it's generally still recommended to supplement due to frequently low dietary intake.

Recap

So quick recap. If you want higher omega-3 dosing and you need flexibility, choose fish oil omega-3 supplements over cod liver oil. If you want a foundational amount of omega-threes for health maintenance plus a boost of fat soluble vitamins, vitamin A and vitamin D, choose cod liver oil.

If you're pregnant or you may become pregnant, choose fish oil with DHA and avoid the cod liver oil due to its high vitamin A content. If you have low levels of vitamin D, you will generally still need to supplement a separate vitamin D option, not just from cod liver oil having the vitamin D.

Wrapping up both supplements, omega-3 fish oil and cod liver oil can be beneficial. It's not about one being better than the other. It's about thinking what is your health situation? What are your goals and individual needs, and taking your individual diet into consideration.

If you're unsure, it's helpful to work with a registered dietitian like myself or one of my coworkers who can look at your full picture and assess your intake of omega-threes from food to provide beneficial guidance.

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That's it for today's episode. If you found this discussion helpful, share it with someone who could also benefit, and if you have questions you'd like us to answer on a future episode, email us at email@weightandwellness.com or join our Dishing Up Nutrition Facebook group. Thanks for tuning in and have a wonderful day.

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