Saturday, March 8, 2008

Must Know: Facts about fat in Your Diet

Although the effect of the total amount of fat in the diet on blood cholesterol levels has been well documented, the most important effectrelates to the type of fat.

Saturated fats have a profound hypercholesterolemic effect (in other words, they increase blood cholesterol levels significantly) and simultaneously increase concentrations of LDL or 'bad' cholesterol. Sources: Saturated fatty acids are found in both animal and plant products, but animal products (such as butter, cheese, full-cream milk, cream, ice-cream, beef, pork and lamb) are the major source of saturated fat in the average South African diet. Similarly, hard or brick margarine (the product packaged in a wrapper) is high in saturated fat; soft of 'tub' margarine is the healthier alternative, since it is low in this type of fat and higher in polyunsaturated fats. Using a polyunsaturated fat will also help to improve your P:S ratio (see below). Coconut oil, cocoa butter, palm oil and palm kernel oil are common 'saturated' vegetable fats which are generally found in many commercially baked goods such as biscuits, also in non-dairy creamers, cake mixes and chocolates. Read labels carefully if youwant to avoid these products.

Diet Start

Mono-unsaturated fats were previously thought to be 'neutral' intheir action on blood cholesterol levels, but recent studies suggest that these fatty acids may play a useful role in the dietary prevention of CHD, since they appear to have most of the benefits of polyunsaturated fatty acids.

Sources: Olive oil, avocado pears and nuts are rich sources of monounsaturated fat.

Polyunsaturated fats lower blood cholesterol levels as well as the concentraton of LDL cholesterol.

Sources: Sunflower oil, tub margarine.

There are two classes of polyunsaturated fatty acids, namely omega-3 and omega-6, which have a variety of functions in the body. Omega-3 fatty acids are found in some vegetable oils and, in particular, in fatty fish. Eicosapentanoic acid (EPA) - a fatty acid which falls into thissub-class - is derived from fish and is highly concentrated in fish oils. Research suggests that this fatty acid may play a beneficial role in a diversity of biological processes including arthritis, eczema and even cancer. However, the role of omega-3 fatty acids - and specifically EPA - in the treatment of hypertension and raised serum cholesterollevels remains controversial.

It seems from studies done so far that fish and fish oil supplements may lower triglyceride levels, reduce clot formation, decrease blood viscosity (or thickness) and lower blood pressure levels. However, the optimal doses of these fatty acids have not been established and until answers to these questions are known, the widespreadsupplementation of omega-3 fatty acids is not recommended. It is a better idea to substitute fish, especially fatty fish (such as salmon, galjoen, snoek, pilchards and tuna) as a source of protein in two or three meals a week, thus consuming a whole spectrum of nutrients and not just a single fatty acid fraction.

The P:S ratio

The ratio of polyunsaturated to saturated fatty acids in a diet is known as the P:S ratio. The typical South African diet has a P:S ratio of 0.5:1.0 (in other words, twice as much saturated as polyunsaturated fat). However, the eating plan recommended for the prevention of CHD suggests a ratio of at least 1:1 (or an equal quantity of both), which for most of us means restricting our saturated fat intake and replacing it, where practical, with polyunsaturated fat such as fish or sunflower oil. Most of the comparisons between the effects of saturated and polyunsaturated fat have indicated that gram for gram, the blood cholesterol-raising effect of saturated fat is up to two times greater than the cholesterol-lowering effect of polyunsaturated fat.

Many studies have shown that so-called 'intervention trials' aimed at lowering raised blood cholesterol levels, reduce the CHD risk and slow the progress of arterial damage. These studies provide strong support for recommendations for a considerable overall decrease in dietary fat by the general public, from the present 35-38°/o to 30% of total kilojoule intake, and a decrease in saturated fat to 10% of total kilojoule intake.

... andjoyohoxing