Oily Fish (salmon, mackerel, herring, sardines, anchovies)
As mentioned previously Eskimos, who eat a reasonably high fat diet, have one of the lowest incidences of heart disease known. This question concerned two investigators, Dr Jorn Dyerberg and H.O. Bang, at the Alberg Hospital in Holland. On examining the incidence of heart disease among Eskimos living in Greenland, they found that when the Eskimos moved to Eastern Canada and ate the same diet as the Canadians, their incidence of heart disease went up to that of their fellow Canadians within one generation. This indicated that their protection against heart disease was not necessarily related to genetics, but must be attributable to some unknown unique factor in their diet. The culprit must have had something to do with the fat content of the diet.
The chemical examination of the oils in the Eskimo diet found that there was a reasonably high concentration of an unusual fatty acid called Omega-3 containing eicosapentaenoic acid, (EPA) and docosahexaenoic acid, (DHA). This fatty acid, which is chemically related to linolenic, linoleic, and arachidonic acids, is apparently manufactured by small unicellular algae that live in the ocean, and has been passed up through the food chain where it is concentrated in the fat tissue of the higher fish.
Cardiovascular Protection
Dr William Connor, professor of medicine and head of the University of Oregon’s clinical nutrition section, found that a 10 day diet of salmon, which contains high levels of Omega-3, lowers blood cholesterol by up to 17% per cent in healthy volunteers, and by 20 per cent in patients who have elevated cholesterol. Triglyceride levels in the blood fell by as much as 40 per cent in healthy volunteers and as much as 67 per cent in high triglyceride patients. ‘The greatest effect seems to be in patients with elevation of both blood cholesterol and triglyceride levels,’ says Dr Connor. ‘The higher these levels are when the fish oil program is started, usually the greater the fall.’
In addition, Omega-3 protects against the clumping and unwanted stickiness of a type of blood cell called platelets, which can cause heart attack, stroke, or blockage in other arteries of the body, such as the femoral artery producing a thrombophlebitis. A high concentration of Omega-3 is used by the body to manufacture substances called thromboxane and prostcyclin, which actually prevent platelets from sticking together.
Krill Oil
It has been reported that a daily dose of Krill Oil can be highly beneficial. It is derived from the planktonic crustacean family and it is rich in phospholipids, Omega-3 and antioxidants. One of the best cholesterol lowering foods it has been observed to lower total bad cholesterol levels by 34 per cent and boost good cholesterol levels by 44 per cent.
Olive Oil
It seems that mono-unsaturated fats reduce the capacity of LDL cholesterol to oxidise, which may explain the protective properties of olive oil. However, extra virgin olive oil also contains around 40 antioxidant phytochemicals, so perhaps these phytochemicals are the factors responsible for the health benefits.
To investigate the effect of antioxidants from olive oil on cholesterol, researchers instructed 16 healthy adults to avoid phenol containing foods such as coffee, tea, wine and vegetables for 4 days. On the fifth day adults consumed 50 ml of virgin olive oil – about 3.3 tablespoons – alone or with bread.
The participants avoided all other foods with phenols for the next 24 hours and then ate their regular diet, supplemented by 25 ml of olive oil daily, for a week. Study volunteers were also told to avoid high fat foods such as butter, margarine, cooking oil, nuts, baked foods and eggs.
Blood samples taken before and during the study revealed higher levels of antioxidant compounds, including vitamin E and phenols, after one week. Similarly, levels of oleic acid, the predominant type of fat in olive oil, as well as of mono-unsaturated fatty acids were higher. These changes were associated with a slower LDL oxidation rate.
In addition to the LDL lowering effect of virgin olive oil, the results suggest that an intake of 25 ml/day could increase the resistance of LDL to oxidation because it becomes richer in oleic acid and antioxidants. These benefits could be achieved by including virgin olive oil daily in our diet.
European Journal of Clinical Nutrition April 2002, 56:114-120
Flax Seed
Flaxseed oil is derived from the seeds of the flax plant. Flaxseed oil and flax seed contain substances that promote good health. Flaxseed oil is rich in alpha-linolenic acid (ALA), an essential fatty acid that appears to be beneficial for a variety of conditions. The body converts ALA to EPA and DHA, the forms more readily used in the body.
Studies suggest that flaxseed oil and other omega-3 fatty acids may be helpful in treating a variety of conditions. The evidence is strongest for heart disease and problems that contribute to heart disease. It is important to maintain an appropriate balance of omega-3 and omega-6 (another essential fatty acid) in the diet as these two substances work together to promote health. These essential fats are both examples of polyunsaturated fatty acids, or PUFAs. Omega-3 fatty acids help reduce inflammation and most omega-6 fatty acids tend to promote inflammation. An inappropriate balance of these essential fatty acids contributes to the development of disease while a proper balance helps maintain and even improve health.
A healthy diet should consist of roughly two to four times more omega-6 fatty acids than omega-3 fatty acids. The typical American diet tends to contain 14 to 25 times more omega-6 fatty acids than omega-3 fatty acids and many researchers believe this imbalance is a significant factor in the rising rate of inflammatory disorders in the United States.
In a future article we will look at Soy which scientists agree can help to lower cholesterol levels but there is a more to this protein which will be fully explored next time.
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