Seafood and Cholesterol
In the early 1970s it was noted that although the Inuit (Eskimos) of Greenland had a high fat, high cholesterol diet they had virtually no heart disease. Investigations by two Danish medical researchers concluded that this was due to the high level of Omega-3 polyunsaturates PUFAs in their native diet.
Later epidemiological studies, as well as evidence derived from supplementation studies and clinical trials, indicate that increasing Omega-3 intake has a number of beneficial effects:
- The level of a fat called triglyceride in the blood can go down by as much as 30% high levels of triglyceride encourage the blood to clot.
- Decreased growth rate of atherosclerotic plaque
- Lower blood pressure and reduced blood viscosity improves circulation, reduces workload on heart and risk of arrhythmia.
Cholesterol is a fatty substance manufactured by the liver for body’s requirements. It is found among the lipids fats and oils in the bloodstream and in all your body cells. Cholesterol is an important part of a healthy body because it is used alongside the essential fatty acids to form cell membranes, some hormones, and is needed for a number of other functions.
Having said this, we all know that a high level of cholesterol in the blood – hypercholesterolaemia – is a major risk factor for coronary heart disease. Very little cholesterol is found in foods and the amount ingested does not significantly contribute to the blood’s cholesterol level. However cholesterol is insoluble in blood so, once manufactured, it has to be carried around in the bloodstream coated by proteins. This combination of cholesterol and protein is called lipoprotein.
There are two main types of lipoprotein:
- LDL low density lipoproteins – known as “bad” cholesterol most common cause too much saturated fat in the diet – is the major cholesterol carrier in the blood transferring it from the liver to the cells. Too much LDL cholesterol circulating leads to the formation of a plaque on the walls of the arteries that slowly lead to clogging. A high level of LDL cholesterol reflects an increase in the risk of heart disease.
- HDL high density lipoproteins – known as “good” cholesterol – tends to carry cholesterol away from the cells and arteries and back to the liver, where it is passed from the body. High HDL level seems to protect against heart attack by helping to remove excess cholesterol from plaques and thus slowing their growth.
Your main objective for good health should be to have both a low LDL level and a high HDL level in the blood. Eating saturated fats increases the LDL level and reduces the HDL level. On the other hand, eating unsaturated fats lowers the LDL level and raises the HDL level.
Even small amounts of Omega-3s can make a big difference to health and eating seafood once or twice a week contributes significantly towards supplying the required amount of unsaturated fats.
Although it was once thought that certain molluscs contained high cholesterol levels, this was partly due to an analytical error that confused phytosterols with cholesterol. Although cholesterol is present levels range from 40-60mg/100g meat for mussels to 150-200mg/100g meat for cuttlefish and squid, this is still less than the cholesterol contained in an egg 250mg.
The British Heart Foundation and The American Heart Association as well as The British Nutrition Foundation recommend eating seafood at least two times a week as it reduces the risk of cardiovascular disease.