Fish oils: The omega code

Unless you have been living on a desert island for a couple of years, you can't have missed the barrage of information in the media about the health benefits of fish oils. They have been touted as a panacea for everything from arthritis and heart disease to Alzheimer's and attention deficit hyperactivity disorder.

Scientists have known for some time that a diet rich in omega-3 fats can reduce the risk of cardiovascular disease and reduce levels of triglycerides – the sort of fat found in the blood that has been linked to heart disease. Now, this week, doctors at Ninewells hospital in Dundee have announced the results of a study showing that people suffering from rheumatoid arthritis who regularly took cod-liver oil were able to reduce their medication.

Recently, a large Italian study published in The Lancet showed that fish oils given to more than 4,000 patients after a heart attack helped to prevent a secondary event, prompting the Italian health service to give fish-oil capsules to anyone who has had a heart attack. Last year, NICE (the National Institute for Health and Clinical Excellence) announced that a daily 1mg fish-oil capsule should be prescribed to anyone who has had a heart attack.

So what's so special about fish oils? The magic ingredient is omega-3, the name given to a family of polyunsaturated fatty acids, which the body needs but cannot make itself. It was first recognised as beneficial to health in the 1970s by Danish physicians, who were puzzled by the low incidence of heart disease in the Greenland Inuit, in spite of their very high-fat diet. These studies showed that the Inuit diet of whale meat, seal blubber and salmon appeared to confer a low incidence of cardiovascular disease and other inflammatory diseases such as asthma, rheumatoid arthritis, diabetes and psoriasis.

Omega-3 fatty acids are converted in the body into natural anti-inflammatory substances known as prostaglandins and leukotrienes. Diets high in omega-3 have been shown to improve inflammatory diseases such as rheumatoid arthritis and to lower cholesterol and blood pressure. The advice from the Government is that we should eat at least two portions of fish a week, one of which should be the oily type – sardines, herring, mackerel, trout. Salmon, pilchards, kippers, fresh tuna, anchovies, swordfish, bloater carp and sprats are also rich sources.

However, the Western diet does not contain huge amounts of oily fish, so most of us do not have enough omega-3 fatty acids in our blood. Also, say lipids experts, our diet contains way too much of the other essential fatty acid family, the omega-6s, which compete with omega-3 and generally encourage inflammation. Ideally, we would have a ratio of two omega-6 to one omega-3 – that is, twice as much omega-6 as omega-3.

"Current statistics show that, in this country, the ratio is more like 25:1, and in the US it may be as high as 50:1. This overload contributes to long-term diseases such as heart disease, cancer, asthma, arthritis and depression," says Professor Keith Coupland, the director of the Lipid Nutrition Unit at Hull University.

However, at the moment there is no generic test for levels of omega-3 in the blood, and there is no recommended daily amount of omega-3 – so how can we tell if we are lacking in this essential fatty acid? At a recent symposium on fatty acids and lipids, a lipids expert from Harvard University called for a blood test that could measure omega-3 levels accurately so that doctors could predict who was at risk of heart attack. Coupland believes that if a test such as this was available in GPs' surgeries, people could be encouraged to take more responsibility for their health.

One Glasgow GP is ahead of the game. Dr Tom Gilhooly, who also runs the Essential Health Clinic, offers tests to find out the nutritional status of patients' blood. He then offers advice on dietary change and supplementation. "Working with patients to increase their omega-3 levels can help to treat conditions as varied as MS, depression, drug addiction and Crohn's disease," he says.

Gilhooly has teamed up with Dr Gordon Bell, a biochemist based at the University of Stirling, to offer patients a new blood test that can accurately measure levels of omega-3 in the blood. "At the moment, the usual way to measure omega-3 in the blood is via the blood plasma, which can throw up inaccuracies as it is affected by what a patient has recently eaten. The most accurate way is by testing the red blood cell membrane, which is exactly what our new test can do. The collaboration with the University of Stirling means we can use a sophisticated technique analysing red blood cell fatty acids. This removes the need for patients to fast prior to testing," Gilhooly says.

The test results take five days and, at £99, it is expensive. "We could do the test more quickly, but we would lose some fatty acids and that would compromise its accuracy. We are trying to find ways to speed things up and make the test more affordable," Bell says. The clinic, launched last year, has sent more than 100 samples for testing. "By testing the blood to discover the exact imbalance in our patients, we can tell exactly how much omega-3 they should be taking for optimum health," Gilhooly says. "Ratios I see in my practice can range from 15:1 to as high as 40:1."

Anxious to try out the test, I trotted along to my GP, who was very helpful and agreed to send the blood to Bell's clinic. When the results came, I was thrilled; my profile was very good. My ratio was 7:1 – that means I have seven times as much omega-6 in my blood as omega-3. I felt positively smug; the UK average is 15:1.

But Gilhooly was quick to disillusion me; it seems that even my ratio is not up to scratch, and we should aim for the Japanese average of 3:1. He advised me to eat a portion of oily fish or take a supplement every day to redress the balance.

Diet is the optimum way to get your omega-3s, by eating oily fish. You should cut down on crisps, chips, ice creams, margarine, junk foods and takeaways, which tend to be made with oils high in omega-6. If you take a fish-oil supplement, the normal dose is 500mg to 1,500mg per day, depending on your diet.

"Once the shortfall is known, correcting the ratio is not difficult," Gilhooly says. "We have done a three-month pilot study on a group of businessmen, taking their ratios before and after supplementation with omega-3. At the end, all but one of them was very close to the optimum ratio – quite a dramatic improvement in a very short time," he says.

Gilhooly wants to make the test more widely available, because he thinks it is vitally important. "The collaboration with the university also means we can do more research projects, one of which is to look at the effects of omega-3 on cytokines, the signalling molecules that are important in inflammation. We are hoping to start that later this year," he says.

www.essentialhealthclinic.com

Interesting? Click here to explore further