We all know that omegas are important to our health, but are you entirely clear on which ones do what? And does eating foods with lots of one kind of omega, make up for not getting much of another?

While some fatty acids play roles in similar or closely linked functions within the body, there's a whole load of complex science behind how they really work. Even if you don't know all this science, having a rough idea of the basics will still help.

If you want some clarification, and if you want to make omegas your amigos, read on...

Omega 3

Important for...Heart health, brain function and preventing diseases

Find it in...Oily fish, flax, linseed, walnuts and certain oils

Flax seeds

Arguably the most well-known of the omegas, there's been a wealth of research into omega 3 and its benefits, particularly for heart health and brain function - in children and adult (some studies have even suggested eating fish during pregnancy may improve childhood neurodevelopment), are well documented.

In fact Babi Chana, biochemist and Pharma Nord nutritionist, believes that increasing omega 3 intake is the single biggest change - in terms of health benefits - we could make in our diets.

"Increasing our omega 3 intake can help safeguard against brain and behavioural problems, including mood, behaviour and learning ability, heart and circulatory disease, stroke, pain and inflammation, diabetes, cancer, autoimmune diseases, asthma, skin disorders and all manner of chronic illnesses," she explains.

"Other fats in the diet are used as storage or fuel, but omega 3s are functional and play an extensive role as messenger substances known as eicosanoids, which control blood clotting, blood pressure, pain, inflammation, as well as structural roles in all cell membranes that profoundly affect the sensitivity of each cell to respond to messages from hormones, enzymes, immune signals and neurotransmitters. It is the only substance that gives us the gift of sight; vision is only possible due to the concentration of omega 3s on the retina."

Omega 3 is known as an 'essential' fatty acid as the body can't produce it, "so it's really important you get enough in the foods you eat", notes British Dietetic Association spokesperson, Emer Delaney. "Foods rich in omega 3 include oily fish, like salmon, mackerel, herring, trout and fresh tuna, flaxseed and walnuts. Linseed, rapeseed, soya and walnut oils are other good sources."

Because oily fish may contain contaminates, which overtime could build up in the body to potentially damaging levels, guidelines advise people to eat between two and four portions per week. "Everyone should have oily fish at least twice a week," notes Delaney, pointing out that signs of a deficiency include fatigue, dry skin, memory loss, low mood and poor circulation.

Omega 6

Important for...Heart health, brain function, cell growth and the nervous system

Find it in...Vegetable and sunflower oils, avocados, olives and nuts

Avocado

If you've paid close attention to the health headlines in recent years, you'd be forgiven for being a little confused about whether omega 6 is actually a 'good' or 'bad' fatty acid. So what's the truth?

"It depends what you read!" says Delaney. "Some people believe omega 3 and omega 6 compete with each other in the body, so the ratio you eat them in is important. Other experts believe that both are healthy oils and we shouldn't limit intake of either. As a dietitian, I advise a balance and aim to eat oily fish twice a week."

Like omega 3, omega 6 is vital and plays an important role in heart health and maintaining levels of 'good' cholesterol, as well as in the function of eicosanoids.

Omega 6 is also an essential fatty acid, meaning we get it solely from the foods we consume. But there is a key difference. "Omega 6 is abundant in all the foods we eat, even processed foods and junk foods like cake and pastries," notes Chana.

This means a number of things - some experts believe consuming too much omega 6, along with too little omega 3, may have negative effects, and could even be potentially detrimental to heart health if the balance is especially skewed. This is particularly a concern for people who have generally unhealthy diets with lots of processed and fatty junk foods.

Another potential pitfall is that some foods may appear labelled as being high in omega 6, giving the impression they're a 'healthy' choice - but this doesn't necessarily mean they're something you should eat a lot of, especially if the product in question is also high in saturated fat and sugar. And lots of omega 6 certainly does not make up for a lack of omega 3, so fish-avoiders should be extra careful.

Omega 7

Important for...Healthy mucous membranes

Find it in...Some dairy products and high quality supplements

Eggs

Unlike 3 and 6, omega 7 is not an essential fatty acid, which means the body can produce it - though some people could still be lacking and benefit from topping up.

"Omega 7 is particularly important as the preferred building block for all our mucous membranes, which are all the wet linings of the eyes, ears, nose, throat, gastrointestinal, vaginal, urinal and anal passages," explains Chana.

"Dryness, irritation or any conditions affecting the health of these linings, such as dry, red sore eyes, post-menopausal dryness or inflammatory bowel conditions could benefit from omega 7 supplements," she adds, pointing out that in some cases, people with these conditions who've found topical treatments ineffective have reported significant positive results from a supplement (always consult your doctor if you have existing health conditions and/or are on medication).

"Once consumed, the body delivers omega 7 to structurally rebuild these delicate linings and improve both the integrity and barrier function of these walls. Lubrication, soreness, redness and irritation are significantly improved and can affect quality of life bringing considerable relief, even after long-term conditions."

Omega 9

Important for...General functioning

Find it in...Olive oil, nuts, avocado

Nuts

"Omega 9 is not an essential part of your diet, because it's made by your body, so people may not be as familiar with it," says Delaney.

While not really as exciting a health-booster as 3 and even 6, omega 9 still plays an important role. "It helps cells and nerves work and it can help lower your risk for developing cardiovascular disease," Delaney adds. Providing you are well and eat a sensible, balanced diet, your omega 9 levels should be fine. Olive oil contains high quantities of it, but again, balanced consumption is advised.