Overweight and Cholesterol intake in your diet

The effect of dietary cholesterol on cholesterol levels in the blood is less crucial and more variable among individuals than the effects of saturated fat - nevertheless, it plays an important contributory role and this is why the recommended limit for cholesterol consumption has been set at 300 mg per day. Of course, the average person has no means of measuring the amount of cholesterol in various foods, but what you can do is identify those which are rich sources and ensure that you eat them in moderation only (see below).

Foods high in cholesterol

Beef, butter, chicken, turkey, duck, cream, all full-cream dairy products, fish, lamb , mutton, pork, tongue

Foods very high in cholesterol

Brains, caviar, egg yolks, giblets, kidneys, liver, prawns, shrimps

These foods are also high in saturated fat and should be eaten only occasionally. (Saturated fats raise blood cholesterol levels far more than does dietary cholesterol in animal foods.)

Overweight and heart disease

The role of obesity or overweight as an independent risk factor for CHD has not been clearly established, but what is known is that it is associated with risk factors such as raised LDL (`bad') cholesterol and total blood cholesterol, lower HDL (`good') cholesterol, hypertension(high blood pressure) and diabetes mellitus. Hypertension is much more common in overweight people; moreover, when weight is reduced and then maintained at a lower level, blood pressure tends to drop as well - if the weight goes up again, so does the blood pressure. There is a particularly strong link between obesity and hypertension in children and for this reason, it is important that children and adolescents do not gain excess weight - in fact, maintaining an ideal body weight should be a goal for the population in general.

Obesity also seems to be a significant, independent predictor of coronary heart disease, especially in women. Although women generally have lower blood cholesterol levels than men, these tend to rise after the menopause. Smoking also seems to be on the increase in women and this can be an important contributory factor. It has been shown that if you are overweight, a cigarette smoker and you take oral contraceptives, your risk of having a heart attack increases significantly.

In summary, the maintenance of ideal body weight by means of a combined diet and exercise programme makes good sense because of the relationship between obesity and an increased risk of heart disease. Also, for a large number of people who suffer from hypertension, weight control can be an effective way of treating the problem and may prevent the necessity for drug treatment.

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.

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.

Hints from Dietary recommendations to see how important is diet?

How important is diet?

There is a lot of international and local evidence to suggest that diethas a significant effect on many of the risk factors associated with coronary heart disease. As already discussed above, the most important of these - as regards both the cause and the treatment of CHD - is hypercholesterolaemia or a high blood cholesterol level.

The second important risk factor which is obviously linked to diet is overweight - or its exaggerated form, obesity - which in turninfluences both blood cholesterol and blood pressure levels. Tocomplicate matters, overweight sometimes develops when another risk factor such as cigarette smoking is stopped. Finally, the third riskfactor - hypertension or high blood pressure - is greatly affected by dietary sodium (salt) and possibly potassium consumption.

In view of all the above and because of increased concern about the high incidence of coronary heart disease in this country, SouthAfricans are being urged to change their eating habits significantly or face the fact that they could become part of the statistics.

Dietary recommendations

• Total fat intake should not exceed 30% of total daily kilojoule intake.
• Intake of saturated fatty acids should be no more than 10% of daily energy intake.
• Intake of poly-unsaturated fatty acids should not exceed 10%. * Intake of trans fatty acids should be limited.
• Cholesterol intake should not exceed 300 mg per day.
• In cases of under-nutrition, relevant and affordable protein sources
  should not be limited for the sake of limiting cholesterol intake.
• Salt intake should be limited to 3 g of sodium per day (which amounts to 7,5 g or 1¹/₂ teaspoonful of salt per day or 1 teaspoon plus that which is present in foods.
• Fibre intake should be kept at 20-30g per day in the form of fresh,unrefined foods.
• The maximum daily intake of alcohol should be 2-3 tots (10-20 g).
• Ideal weight must be maintained through adequate physical exercise and controlled food intake.

How fibre affects the body continue...

Appendicitis

Appendicitis is inflammation of the appendix, the small blind-ended tube at the beginning of the large bowel. Although the underlying causes of appendicitis are not clearly understood, there is evidence that regular intake of fibre may prevent the development of the disease.

Hiatus hernia, varicose veins and piles

Many doctors believe that abdominal straining due to constipation encourages the development of conditions such as hiatus hernia (where the top of the stomach is pushed upwards, out of the abdomen and into the thoracic cavity), varicose veins and haemorrhoids (piles). It is often necessary to have surgical treatment for these conditions. Treating constipation with high fibre diets and, as a result, avoiding straining, may prevent these problems and may even reduce the need for more drastic treatment in some cases.

Coronary heart disease (CHD)

Coronary heart disease is the most common cause of death in affluent Western countries (see page 151). A large number of factors influence the development of the disease, of which raised blood cholesterol levels, high blood pressure and hypercoagulability (the tendency of the blood to clot too easily) are probably the most important.

Researchers believe that high-fibre, low fat diets protect against CHD by lowering blood cholesterol and probably also by decreasing blood pressure and the clotting ability of blood. It is especially the water soluble or gel-forming dietary fibres - found in oats, legumes and some fruit and vegetables - which help to lower cholesterol levels. While it should be borne in mind that diet is but one of the many factors which influence the development of CHD, it is also one of the controllable ones.

Diabetes mellitus

There are two forms of diabetes mellitus, a disease characterised by the excretion of glucose (sugar) in the urine (see What is diabetes? on page 175). Both forms are today treated with a high carbohydrate, high fibre, low fat diet. Fibre in the diet normalizes the body's response to dietary carbohydrate (glucose tolerance). A regular high intake of dietary fibre also improves insulin function by increasing the sensitivity of muscle and fat cells to the hormone.

Gallstones

The body manufactures these crystalline substances when the amount of cholesterol in the bile is so high that the bile salts cannot keep it in solution. The stones may block bile ducts between the liver and gall bladder or between the gall bladder and small intestine, resulting in severe pain and even jaundice. As in the case of other diseases of affluence, a number of factors may contribute to the development of gallstones. It has however been shown that high fibre intakes stimulate the production of those bile salts which keep cholesterol in solution, thus decreasing the risk of gallstone formation. Populations who follow high fibre diets have a significantly lower risk of the disease than those on the average refined Western diet.

To what degree is fibre involved?

Although research has proved that dietary fibre has a positive effect on body functions in general, the degree to which it is involved in the risk and development of the above diseases is still unclear. Studies are hampered by the fact that a variety of causes play some role and also because high-fibre diets differ in more than one respect from low-fibre ones. For example, they usually have a lower fat content - especially saturated fatty acids from food of animal origin - and are higher in vitamins and minerals. These factors could add to the beneficial effects seen in people who eat a high-fibre diet.

What is diabetes?

Diabetes is a disorder in which the pancreas cannot produce enough insulin, a hormone which prevents blood sugar levels from rising too high, or in which the insulin that has been produced does not function properly. It does this by helping body cells to take up glucose - either to metabolise to energy or to store as glycogen or fat.

If an individual manufactures too little insulin, there are two possible forms of treatment: The young, more severely affected diabetic can only survive if given daily injections of insulin for the rest of his or her life. However, if diabetes develops at a later age, treatment with pills is usually effective. These pills are not insulin; they are essentially compounds which give the pancreas the necessary stimulus to produce more insulin to cope with the carbohydrate (sugars and starches) which the individual eats. Because sugar causes a dramatic rise in blood sugar levels, diabetics should obviously avoid it in their diets; indeed, they should avoid all unnecessary food in general if they are overweight, as not only is the insulin requirement related to food intake, but excess weight has an aggravating effect on the condition. Obese diabetics who develop the disease in later life can often be treated by diet alone.

A low fat, high fibre intake - which 'dilutes' the contents of the digestive tract - slows down the passage of glucose into the blood stream and hence the elevation of the blood sugar is less dramatic.