Tucked away in Marylebone Lane, London, is arguably the capital’s best fish and chip shop. The Golden Hind has served the area for 70 years, during which time its decor hasn’t changed. It is famed for its friendliness, celebrity customers and the quality of its fish. Doctors recommend eating fish twice a week, with one of the types being oily.

A recent GP study in South Wales has suggested that omega-3 found in oily fish is not as useful in preventing heart disease as was supposed. However, the discrepancy between the results and the mine of evidence that omega-3 fatty acids are linked to a lower incidence of heart diease remains unexplained.

Omega-3 lowers blood pressure and reduces serum triglycerides, one of the fats circulating in the blood. So marked has been the effect of fish oil that it has been approved by National Institute of Clinical Excellence as a way to lower serum triglycerides. This is important as there is an association between high levels of triglycerides and heart attacks.

Omega-3 fats may also reduce the tendency of the blood to clot and reduce the inflammatory reaction in the arterial lining that is part of the faulty cardiovascular system often found in patients with heart disease.

Previous research has shown that a diet with adequate omega-3 reduces the risk of sudden cardiac death by up to 45 per cent. A different survey looked at the effect of fish oils on second and subsequent heart attacks and found that these were reduced by 30 per cent.