Parenting

How much it is reasonable to modify children’s diets depends on specific dietary risk factors for vascular disease and to what extent they operate from childhood.
Serum lipids
As a 'hunter-gatherer', man's 'natural diet' was essentially omnivorous including seeds, roots, berries, and fruits supplemented with occasional meat. Animals in the wild are generally lean so dietary fat would be relatively high in unsaturated fatty acids and low in saturated fatty acids. The western diet has moved towards a much greater intake of animal fats, partly because we eat more meat, and partly because meat from animals reared commercially and selected for rapid weight gain contains more structural fat. A diet high in saturated fats correlates both with cholesterol levels and with coronary heart disease levels found in a community.

Cholesterol is essential in the metabolism of steroid hormones, bile salts, and cell membranes, and triglyceride plays a major part in energy storage in the body. Cholesterol is carried in the plasma in various forms depending on the nature of the neutral fats to which it is attached. Fat and cholesterol are transported through the circulation by carriers called lipoproteins:

- atherogenic low density lipoprotein (LDL),70% of circulating cholesterol
- cardio protective high density lipoprotein (HDL)
- high levels of triglycerides (TGs) with low levels of HDL increase risk of heart disease.

Total cholesterol is associated with atherosclerosis because high blood cholesterol levels are usually due to increases in LDL.

Both LDL and HDL fractions can be influenced by dietary intake, although dietary cholesterol has only a small effect on LDL cholesterol in the blood. High levels of unsaturated fats in the diet such as sunflower and certain other vegetable oils tend to raise HDL and lower LDL-cholesterol levels. People from Mediterranean countries with high intakes of olive oil have low LDL and high HDL-cholesterol levels. This is of particular interest because olive oil is rich in monounsaturated fatty acids.

There is an inverse relationship between fish consumption and heart disease which may be related to the intake of the polyunsaturated omega-3-fatty acids. These fatty acids reduce triglyceride but possibly exert their main effect by inhibiting thrombosis. Most other animal fats have the reverse effect. Not all vegetable oils are high in unsaturated fatty acids. The so-called 'tropical oils' such as palm oil and coconut oil are little different from animal fats in this respect. They are very high in saturated fats and their inclusion in many processed foods such as biscuits and cakes or as cooking oils represents a hidden hazard. The label Vegetable oil' is not a guarantee of satisfactory fatty-acid composition. Even oils which should be rich in polyunsaturated fatty acids may be affected by the process of manufacture. In general 'cold-pressed' oils are better than those where some heat extraction method has been used because repeated heating leads to a gradual hydrogenation turning polyunsaturated fatty acids into trans fatty acids. Major contributors of trans fatty acids in the diet are margarine, baked, and fried foods. Both trans fatty acids and saturated fatty acids increase total and LDL cholesterol concentrations in blood. As yet, however, there is no conclusive evidence that trans fatty acid intake is a risk factor for coronary heart disease but it is recommended that trans fatty acid intake should not rise above the current 2% of energy intake.

Diet is not the only factor which influences levels of cholesterol fractions. There appear to be hereditary factors which determine which individuals will increase their LDL-cholesterol levels on unfavorable diets, whereas others can cope with them with impunity. Exercise raises HDL and lowers total cholesterol. Smoking has the opposite effect and falls in HDL-cholesterol have been demonstrated in teenagers within a few months of commencing smoking. Certain types of personality seem to be associated with adverse blood cholesterol patterns. These additional factors have led at least some experts to doubt whether changing the dietary patterns of the whole population is the best way to tackle the problem of atherosclerosis, believing that attention should be concentrated on those most at risk.