Omega-3 fatty acids are a group of polyunsaturated fats that your body cannot produce on its own. You have to get them from food or supplements, full stop. Despite decades of research confirming their value, surveys consistently show that Australians fall well short of the amounts associated with measurable health benefits. Understanding what omega-3s actually do makes it far easier to take them seriously.
The three main types of omega-3
Not all omega-3s are the same. There are three you need to know about: ALA (alpha-linolenic acid), EPA (eicosapentaenoic acid), and DHA (docosahexaenoic acid).
ALA is found in plant foods like flaxseed, chia seeds, and walnuts. It's the most common form in the Australian diet, but it's also the least potent. The body converts only a small fraction of ALA into EPA and DHA, the two forms that carry most of the documented health benefits. That conversion rate sits below 10 per cent in most adults, and often much lower.
EPA and DHA come primarily from marine sources. Fatty fish like salmon, mackerel, sardines, and anchovies are the richest dietary sources. These two forms are directly usable by the body without conversion, which is why they're the focus of most clinical research.
What omega-3 actually does in the body
The evidence base for omega-3 is substantial. EPA and DHA are built into the membranes of virtually every cell in the body, where they influence how cells communicate and respond to signals. In the brain, DHA is a structural component of neurons. Low DHA levels have been linked to cognitive decline and depression in studies published by bodies including the National Health and Medical Research Council.
EPA plays a larger role in reducing inflammation. Chronic inflammation sits behind conditions including heart disease, type 2 diabetes, and rheumatoid arthritis. This connection is why omega-3 research so often overlaps with cardiovascular health. The evidence on heart outcomes is mixed depending on baseline diet, but the anti-inflammatory mechanism is well established.
DHA is also critical during pregnancy. The developing brain accumulates DHA rapidly in the third trimester, which is why pregnant women are typically advised to increase their intake. Australian dietary guidelines recommend pregnant and breastfeeding women aim for at least 200mg of DHA per day. Many don't get close.
It's worth noting that omega-3 doesn't operate in isolation. If you're also curious about how other nutrients interact with cellular health, what magnesium does and why Australians tend to be deficient covers similar ground from a minerals perspective.
How much do you actually need?
The Heart Foundation of Australia recommends at least 500mg of combined EPA and DHA per day for general heart health. For people with existing heart disease, that figure rises to around 1,000mg. Two to three serves of fatty fish per week gets most people there without supplements.
A standard 100g serve of Atlantic salmon delivers roughly 2,000mg of combined EPA and DHA. Canned sardines in oil come in around 1,500mg per 100g. Tinned tuna, despite its reputation as a health food, contains far less, typically under 300mg per 100g because it's a leaner species.
For people who don't eat fish, algae-based omega-3 supplements provide EPA and DHA directly from the same source fish get theirs. These are the only plant-derived supplements that bypass the ALA conversion problem entirely.
Signs you might not be getting enough
Omega-3 deficiency doesn't announce itself dramatically. Dry skin, brittle nails, fatigue, and difficulty concentrating are common low-grade signs, but they're non-specific enough to point to all sorts of causes. The clearest signal is simply a diet low in fatty fish and with no supplementation.
Chronic inflammation is harder to detect without testing, but it's one reason researchers keep returning to omega-3 in studies on long-term disease risk. If you already read up on what inflammation does to the body, the omega-3 connection should make immediate sense: these fats are among the most direct dietary tools for modulating the inflammatory response.
Supplements: worth it or not?
Fish oil supplements dominate the omega-3 market. Blackmores, one of Australia's largest supplement brands, sells fish oil as its top product. Not all capsules are equal. Cheaper products often contain oxidised oil, which is not just less effective but potentially counterproductive. Look for products that list EPA and DHA content separately, not just total fish oil weight, and check for a third-party purity certification.
The form matters too. Triglyceride-form omega-3 absorbs better than the ethyl ester form found in many budget products. Taking capsules with a meal containing fat improves absorption further.
For most Australians, food-first is a better default than reaching for a pill. Two serves of oily fish a week, plus regular inclusion of walnuts, chia seeds, and flaxseed as ALA sources, covers a meaningful portion of the requirement. Supplements make sense when dietary intake is consistently low, during pregnancy, or when a health professional has identified a specific deficiency.
The omega-6 ratio problem
One factor that often gets overlooked is the balance between omega-6 and omega-3 fats. Both are polyunsaturated, but they compete for the same enzymes in the body. The modern Australian diet is heavy in omega-6, largely through vegetable oils in processed foods, and light in omega-3. This imbalance tips the body toward a more inflammatory state.
Ancestral diets are estimated to have carried an omega-6 to omega-3 ratio of roughly 4:1. Most Australians today consume ratios closer to 15:1 or higher. Increasing omega-3 intake while moderating processed food consumption shifts that ratio back toward a healthier range. You don't need to count every gram. Eating more fish and less takeaway gets you most of the way there.