Nutritional oils: What they are and why they matter

Nutritional oils are among the most widely studied dietary fats in modern nutrition science.

Found naturally in fish, seeds, nuts and algae, these oils provide fatty acids that the body cannot produce on its own, making them an essential part of everyday eating. Omega-3s, in particular, have attracted significant research attention for their role in cell structure and normal physiological function across multiple body systems.

This article explains what nutritional oils are, how omega-3, omega-6 and omega-9 fatty acids differ, where they come from, and how they fit into a daily wellness routine. Whether you’re new to supplements or simply want a clearer picture of what these oils actually do, this is a practical starting point.

What are nutritional oils and why are they important?

Nutritional oils are a broad term for dietary oils valued primarily for their fatty acid content rather than their use in cooking. The category includes fish oil, krill oil, flaxseed oil, algal oil, evening primrose oil and hemp seed oil, among others. What connects them is their concentration of polyunsaturated fatty acids (PUFAs), which play structural and functional roles throughout the body.

Fatty acids are building blocks of cell membranes. Every cell in the body is enclosed by a lipid membrane that controls what moves in and out, and the types of fatty acids present in that membrane influence how flexibly it functions. This is why the balance and type of dietary fat matters, not just the total amount consumed.

The most studied nutritional oils are those rich in omega-3 fatty acids, specifically EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). These long-chain omega-3s are found predominantly in marine sources and are the forms most directly used by the body. Plant-based omega-3s provide ALA (alpha-linolenic acid), which the body can convert to EPA and DHA, though conversion rates are low. A review published in the International Journal for Vitamin and Nutrition Research found that conversion of ALA to EPA is approximately 6%, while conversion to DHA is around 3.8%. This limited conversion is why marine-sourced omega-3s receive particular emphasis in dietary guidelines.

Understanding omega-3, omega-6 and omega-9 fatty acids

The names omega-3, omega-6 and omega-9 refer to the position of the first double bond in each fatty acid’s chemical chain. That structural difference determines how the body uses each type.

Omega-3 fatty acids

The three main omega-3s are ALA, EPA and DHA. ALA is found in plant foods like flaxseeds, chia seeds and walnuts. EPA and DHA come primarily from oily fish (salmon, sardines, mackerel), krill and microalgae. The body uses EPA and DHA for cell membrane structure, and they are particularly concentrated in the brain, retina and heart tissue. Omega-3s are classified as “essential” because the body cannot synthesise them from scratch; they must come from food or supplementation.

Omega-6 fatty acids

Omega-6 fatty acids, particularly linoleic acid (LA), are found in vegetable oils (sunflower, safflower, soybean), nuts and seeds. They are also essential fatty acids, and they contribute to skin barrier function, cell signalling and normal growth. The typical Australian diet tends to be much higher in omega-6 than omega-3, largely because vegetable oils are widely used in processed and packaged foods. The ratio between omega-6 and omega-3 intake has attracted research interest, with some scientists suggesting that a lower ratio may be more favourable for long-term health.

Omega-9 fatty acids

Omega-9s, such as oleic acid, are found abundantly in olive oil, avocados, macadamia nuts and almonds. Unlike omega-3 and omega-6, omega-9 fatty acids are not classified as essential because the body can produce them. They are monounsaturated fats and form a standard part of a Mediterranean-style eating pattern.

Common types of nutritional oils and where they come from

Nutritional oils come from a range of marine, plant and animal sources. Each has a distinct fatty acid profile, and the type you choose depends on your nutritional goals and dietary preferences.

Fish oil is the most common source of EPA and DHA globally. It is derived from oily fish such as sardines, anchovies, mackerel and salmon. Concentration varies between products: a standard 1,000 mg fish oil capsule typically contains around 300 mg of combined EPA and DHA, while concentrated formulas deliver substantially more per capsule.

Krill oil is sourced from small Antarctic crustaceans. It provides EPA and DHA in phospholipid form and contains the antioxidant astaxanthin, which gives it a distinctive red colour.

Algal oil is extracted from microalgae and offers DHA (and in some strains, EPA) without any animal-derived ingredients. It is the primary vegan and vegetarian source of long-chain omega-3s and is also used in some supplements designed for specific health goals like cognitive support.

Flaxseed oil is the richest plant source of ALA. It is cold-pressed from linseeds and provides omega-3 in a form that requires conversion to EPA and DHA in the body.

Evening primrose oil is rich in gamma-linolenic acid (GLA), an omega-6 fatty acid. It is commonly used in women’s health formulations.

Why omega-3 is considered an essential nutrient

The word “essential” in nutrition has a specific meaning: it refers to a nutrient the body requires but cannot manufacture internally. Omega-3 fatty acids meet this definition. Without dietary intake of ALA (and ideally preformed EPA and DHA), the body cannot maintain adequate levels.

EPA and DHA are incorporated into cell membranes throughout the body, where they contribute to membrane fluidity, cell signalling and normal inflammatory responses. DHA is found in high concentrations in brain tissue and the retina, while EPA is involved in the production of signalling molecules called eicosanoids.

Australian intake data paints a clear picture of a gap between recommended and actual consumption. An analysis of the 2011–2012 National Nutrition and Physical Activity Survey found that fewer than one in four Australian adults meet the NHMRC’s Suggested Dietary Target for long-chain omega-3s. Among those not taking supplements, only about 10% reached recommended levels. The Heart Foundation recommends 250–500 mg of combined EPA and DHA daily from two to three serves of fish per week.

Globally, the picture is similar. A 2024 update to the Omega-3 World Map assessed data from over 340,000 individuals across 48 countries and found that omega-3 status was low to very low in most regions. Australia fell into the “low” category, with an Omega-3 Index between 4% and 6%.

Everyday health benefits of omega-3 oils

Omega-3 fatty acids contribute to normal function across several body systems. The evidence base varies by area, so here is what the research supports with the most consistency.

Heart and cardiovascular system

EPA and DHA play a role in maintaining cardiovascular system health. They contribute to normal heart function and may help maintain healthy blood lipid levels. The Heart Foundation’s position on omega-3s recommends all Australians aim for 250–500 mg of marine-sourced omega-3 daily as part of a heart-healthy eating pattern.

Brain and cognitive function

DHA is the most abundant omega-3 in the brain, where it forms a structural component of neuronal cell membranes. Research into omega-3 supplementation and cognitive function has produced varied results depending on the population studied. A 2024 systematic review and dose response meta-analysis published in BMC Medicine found that omega-3 supplementation showed beneficial effects on executive function, with an upward trend within the initial 12 months, particularly at daily intakes above 500 mg.

Joint health

Omega-3 fatty acids have anti-inflammatory properties that may contribute to mild joint comfort. EPA, in particular, is involved in the body’s inflammatory response pathways. Fish oil supplementation is one of the more commonly researched nutritional approaches to supporting joint health, with the strongest evidence relating to mild joint symptoms.

Eye health

DHA is a major structural fatty acid in the retina. Adequate dietary DHA intake contributes to the maintenance of normal vision, which is why many eye health formulations include DHA from either fish or algal sources.

How nutritional oils fit into a daily supplement routine

For people who eat oily fish two to three times per week, dietary intake may be sufficient to meet basic omega-3 needs. The reality is that many Australians don’t consume fish this regularly. This is where nutritional oil supplements can play a role. A daily fish oil or algal oil supplement provides a consistent, measured dose of EPA and DHA that isn’t dependent on weekly meal planning. Consistency matters with omega-3s: these fatty acids are incorporated into cell membranes gradually over weeks, so regular daily intake is more useful than occasional large doses.

Fish oil is best absorbed when taken with a meal that contains some dietary fat. This doesn’t need to be a large amount; the fat in eggs, avocado, nuts or a drizzle of olive oil is sufficient to support absorption of the omega-3 fatty acids.

If you’re taking other supplements alongside fish oil, there’s generally no issue. Fish oil is well tolerated when combined with multivitamins, magnesium, vitamin D, and vitamin C. Fat-soluble supplements (fish oil, vitamin D) can be grouped together at mealtimes for convenience. However, it is best to check with a health care professional if you take any other supplements or medication.

Choosing a quality fish oil for everyday wellness

Not all fish oil products deliver the same amount of omega-3 per capsule. When comparing options, focus on the EPA and DHA content listed on the label rather than the total fish oil weight. A product labelled “1,000 mg fish oil” may contain as little as 300 mg of actual omega-3s, while a concentrated formula can deliver significantly more.

Purity testing is another consideration. Reputable manufacturers test for heavy metals (mercury, lead), PCBs and oxidation levels. Low oxidation matters because rancid fish oil loses efficacy and may cause digestive discomfort, such as a fishy aftertaste or mild nausea.

For those looking for a concentrated option, Blackmores Omega Triple Super Strength Fish Oil provides 540 mg EPA and 360 mg DHA per capsule, delivering triple the omega-3 concentration of a standard Blackmores fish oil 1000 capsule. This means fewer capsules to reach your daily target, which can simplify a supplement routine.

If your nutritional goals are more specific, the Blackmores Omega range includes products formulated for particular areas of health, each with different active ingredient profiles and TGA-listed indications. Your pharmacist or healthcare professional can help you identify which product aligns with your individual needs.

Frequently asked questions

What is nutritional oil?

Nutritional oil is a dietary oil valued for its fatty acid content, particularly polyunsaturated fatty acids like omega-3s. Common examples include fish oil, krill oil, flaxseed oil and algal oil. These oils provide fatty acids the body needs for normal cell function, but cannot produce on its own.

Are nutritional oils the same as fish oil?

Fish oil is one type of nutritional oil, but the category also includes plant and algae-based oils. Fish oil is the most widely used source of the long-chain omega-3s EPA and DHA, while flaxseed oil provides the plant-based omega-3 ALA.

How much omega-3 do you need daily?

The Heart Foundation recommends 250–500 mg of combined EPA and DHA per day for all Australians, achievable through two to three serves of fish per week. The NHMRC’s Suggested Dietary Target for chronic disease risk reduction is higher: 610 mg per day for men and 430 mg per day for women.

Who should consider an omega-3 supplement?

Anyone who doesn’t regularly eat oily fish (two to three times per week) may benefit from a supplement to help meet the recommended omega-3 intake. Vegetarians, vegans and people who dislike the taste of fish can consider algal oil as an alternative source of DHA.

Can I get enough omega-3 from food alone?

If you eat oily fish like salmon, sardines or mackerel two to three times per week, you may meet basic omega-3 recommendations from diet alone. Analysis of Australian dietary survey data suggests most people fall short of this, which is where supplementation can help fill the gap.

Key takeaways

Nutritional oils provide fatty acids that the body cannot produce internally, with omega-3s the most extensively researched. EPA and DHA from marine sources are the forms most readily used by the body, contributing to normal function in the heart, brain, joints and eyes. Australian dietary data consistently show that most people are not meeting recommended omega-3 intake through food alone, and supplementation with fish oil or algal oil offers a practical way to close this gap.

When choosing a nutritional oil supplement, look at the EPA and DHA content per capsule, check for purity testing, and consider whether a concentrated formula might simplify your routine. As with any supplement, consistency over time delivers better results than occasional use.

Always read the label and follow the directions for use.

Disclaimer: This article provides general information only and is not intended to diagnose, treat, cure, or prevent any disease. The information presented is not a substitute for professional medical advice. If you have concerns about your health, please consult your GP or healthcare provider for a personalised assessment and recommendations. Supplements should not replace a balanced diet.