Polyunsaturated fatty acids (PUFAs) are essential fats your body cannot produce independently, making dietary sources crucial for maintaining optimal health. These fats, particularly omega-3 and omega-6 fatty acids, play vital roles in brain function, cardiovascular health, and cellular integrity. Understanding which polyunsaturated fatty acids foods to include in your diet helps ensure adequate intake of these important nutrients. This article explores the best food sources of PUFAs, explains the difference between omega-3 and omega-6 fatty acids, and provides practical guidance aligned with NHS and SACN recommendations for incorporating these essential fats into your daily eating pattern.

What Are Polyunsaturated Fatty Acids and Why Do You Need Them?

Polyunsaturated fatty acids (PUFAs) are a type of fat characterised by multiple double bonds in their chemical structure, which distinguishes them from saturated and monounsaturated fats. The two primary families of PUFAs are omega-3 and omega-6 fatty acids. Some PUFAs are essential, meaning your body cannot produce them independently – specifically linoleic acid (an omega-6) and alpha-linolenic acid (ALA, an omega-3) must be obtained through diet.

Omega-3 fatty acids include alpha-linolenic acid (ALA) found in plant foods, and the longer-chain eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) found primarily in fish. EPA and DHA can be synthesised in limited amounts from ALA in the body. These long-chain omega-3s are important for brain development, cognitive function, and heart health. Omega-6 fatty acids, primarily linoleic acid, contribute to skin barrier function, hormone production, and immune system regulation.

The body uses PUFAs to construct cell membranes, produce signalling molecules called eicosanoids, and maintain the structural integrity of nervous tissue. DHA is particularly concentrated in brain and retinal tissues, highlighting its importance for neurological and visual health. Without sufficient dietary essential fatty acids, individuals may experience dry, scaly skin and poor wound healing, though frank deficiency is uncommon in the UK.

The NHS and Scientific Advisory Committee on Nutrition (SACN) recommend obtaining these fats through a varied diet rich in specific food sources rather than relying on supplements for general health. It's worth noting that while omega-3 supplements are sometimes used at high doses to lower triglycerides, NICE does not recommend routine omega-3 supplementation for cardiovascular disease prevention in the general population. Understanding which foods contain PUFAs and incorporating them regularly into your meals forms the foundation of a heart-healthy, balanced eating pattern aligned with current UK dietary guidelines.

Best Food Sources of Polyunsaturated Fatty Acids

Incorporating PUFA-rich foods into your daily diet is straightforward when you understand which sources provide the highest concentrations of these essential nutrients. Oily fish remains the gold standard for long-chain omega-3 fatty acids, particularly EPA and DHA. The NHS recommends consuming at least two portions of fish per week, including one portion (approximately 140g) of oily fish, with options including:

• Mackerel – exceptionally rich in EPA and DHA (typically 2-3g of omega-3 per 100g)

• Salmon – provides approximately 1.5-2g of omega-3 per 100g serving, varying by species and whether wild or farmed

• Sardines – affordable and sustainable option

• Herring – traditional British source of marine omega-3s

• Trout – freshwater alternative with substantial omega-3 content

For those following plant-based diets, seeds and nuts offer valuable sources of ALA omega-3, though the body converts only small amounts to EPA and DHA. Key plant sources include flaxseeds (linseeds), which contain approximately 2.3g of ALA per tablespoon, chia seeds, walnuts, and hemp seeds. Ground flaxseeds are preferable to whole seeds for optimal absorption.

Vegetable oils represent another important category of PUFA sources, particularly for omega-6 fatty acids. Sunflower oil, corn oil, soybean oil, and rapeseed oil all contain significant amounts of linoleic acid. Rapeseed oil also provides some ALA omega-3.

Other sources include eggs (particularly those enriched with omega-3) and tofu. Avocados, while nutritious, contain predominantly monounsaturated rather than polyunsaturated fats. Some fortified foods, such as certain spreads, yoghurts, and plant-based milk alternatives, now contain added omega-3s, though checking labels for specific content is advisable. When selecting tinned fish, choose varieties preserved in water or olive oil rather than brine to maximise nutritional benefits whilst controlling sodium intake.

Omega-3 vs Omega-6: Understanding the Balance in Your Diet

Both omega-3 and omega-6 fatty acids are important for health, though they have different roles in the body. Modern Western diets typically contain higher proportions of omega-6 compared to omega-3 fatty acids, largely due to the widespread use of vegetable oils in cooking and food processing.

Omega-3 and omega-6 fatty acids are metabolised by the same enzymes and produce different types of eicosanoids (signalling molecules). While it was previously thought that omega-6 derivatives were simply pro-inflammatory and omega-3 derivatives anti-inflammatory, research now shows their relationship is more complex. Both families have important physiological functions, and their effects depend on many factors including overall diet, health status, and genetic factors. The Scientific Advisory Committee on Nutrition (SACN) recognises both types as important nutrients but does not recommend a specific omega-6 to omega-3 ratio.

In practical terms, most UK adults consume adequate amounts of omega-6 fatty acids through vegetable oils, nuts, seeds and grain products. The focus of UK dietary advice is on increasing omega-3 intake rather than restricting omega-6 consumption. Strategies to improve omega-3 intake include:

• Consuming oily fish once or twice weekly

• Choosing rapeseed oil for cooking, which contains both omega-6 and some omega-3

• Incorporating ground flaxseeds or chia seeds into breakfast cereals or smoothies

• Selecting omega-3 enriched eggs when available

• Including walnuts as a snack or meal ingredient

It's important to note that there is no official UK recommendation for a specific omega-3 to omega-6 ratio. The focus should be on ensuring adequate omega-3 intake—particularly EPA and DHA—whilst maintaining overall dietary quality. If you have concerns about your fatty acid balance, particularly in the context of inflammatory conditions, cardiovascular disease, or pregnancy, discuss your dietary pattern with your GP or a registered dietitian who can provide personalised guidance.

How Much Polyunsaturated Fat Should You Eat Daily?

UK dietary guidelines provide specific recommendations for polyunsaturated fatty acid intake to support optimal health whilst maintaining overall fat balance. The Scientific Advisory Committee on Nutrition (SACN) advises that PUFAs should comprise approximately 6.5% of total daily energy intake for adults. For someone consuming 2,000 calories daily, this equates to roughly 14-15g of polyunsaturated fats.

For omega-3 fatty acids, SACN recommends a population average intake of approximately 450mg of combined EPA and DHA daily. This can generally be achieved by eating two portions of fish per week, including one portion (140g) of oily fish, though the exact omega-3 content varies by fish species. The NHS recommends most people eat no more than 4 portions of oily fish per week. Pregnant or breastfeeding women, and women planning pregnancy, should limit oily fish to 2 portions weekly due to potential pollutant exposure, and should avoid shark, marlin and swordfish entirely. Tuna consumption should also be limited during pregnancy.

For plant-based omega-3 (ALA), consuming approximately 1-2g daily from sources like flaxseeds, chia seeds, or walnuts is considered beneficial. The conversion of ALA to EPA and DHA is limited (typically less than 5-10%), so those avoiding fish may wish to consider algae-based omega-3 supplements after consulting their GP.

Regarding omega-6 fatty acids, whilst essential, most UK adults consume sufficient amounts through their regular diet without specific supplementation. The key is ensuring you don't exceed the overall recommendation that total fat intake should not exceed 35% of daily energy, with saturated fats limited to 10% or less.

A practical weekly plan might include:

• One to two portions of oily fish

• One tablespoon of ground flaxseeds several times weekly

• A small handful of walnuts as a snack option

• Cooking with rapeseed oil rather than butter or other saturated fats

If you're considering omega-3 supplements, particularly high-dose formulations, consult your GP first, especially if you take anticoagulant medications, as omega-3s can affect blood clotting. Individuals with fish allergies, specific cardiovascular conditions, or those on lipid-lowering medications should seek personalised dietary advice from healthcare professionals. If you experience any side effects from omega-3 supplements, report them through the MHRA Yellow Card scheme.

Frequently Asked Questions