Overview
A source of energy, the carrier for vitamins A, D, E and K, and the raw material for cell membranes and hormones. Which fats, and in what proportion, matters more than how much.
Why your body needs it
Energy storage, cell membrane structure, hormone production, and the transport of vitamins A, D, E and K. Two fatty acids — linoleic and alpha-linolenic — are essential and must be eaten.
Food sources
- Oily fish — the useful long-chain omega-3s
- Olive oil
- Nuts and seeds
- Avocado
- Flax and chia (short-chain omega-3)
- Eggs
Conversion of plant omega-3 to the long-chain forms in fish is poor — under 10% — so fish or algae oil is not interchangeable with flax.
Recommended intake
20–35% of energy · omega-3: 1.6 g (men), 1.1 g (women) for most adults. The upper limit, past which harm becomes likely, is None as such; trans fats should be as low as possible.
Reference intakes are population figures. Pregnancy, illness, age and medication all move an individual’s needs, which is one of several reasons this page is information rather than advice.
Low fats / deficiency
Most at risk: Very low-fat diets, fat malabsorption conditions.
Possible causes
Essential fatty acid deficiency is rare, seen with very low-fat diets, fat malabsorption and long-term parenteral nutrition without lipids. Low omega-3 intake is common without amounting to deficiency.
Signs & symptoms
Rare. Dry scaly skin, poor wound healing, and in infants, impaired growth and vision.
Every sign here has other, often likelier, explanations. A list of symptoms is a reason to look into something, never a diagnosis.
Testing / diagnosis
Not routinely tested. A blood lipid panel measures cardiovascular risk factors, not whether your fat intake is adequate — a distinction often missed.
Food strategies
Oily fish twice a week for long-chain omega-3s; olive oil, nuts, seeds and avocado for unsaturated fats. Walnuts, flax and chia give the plant form, which converts to the long-chain form only inefficiently.
Supplements
Fish oil raises omega-3 intake; algal oil does the same for vegans. High doses increase bleeding risk. Cod liver oil also carries vitamin A, which matters if you take other supplements containing it.
Safety
Fat is energy-dense, so excess contributes to weight gain. Industrial trans fats raise cardiovascular risk and are now largely banned in Canada.
Interactions: High-dose fish oil increases bleeding risk alongside anticoagulants.
When to seek professional advice
Speak to your doctor about cholesterol results rather than acting on them alone, and before taking fish oil if you are on an anticoagulant or approaching surgery.
This page is general reference information, not medical or dietetic advice, and it cannot account for your health history or medications. Decisions about testing, supplements or significant dietary change belong in a conversation with your doctor, pharmacist or a registered dietitian.