Patricia Thompson, Contributor
COOKING OILS are much used in local cuisine but there is controversy as to which one to choose. Cooking oils extracted from plants are called vegetable oils including corn, soy, coconut, canola, and olive among others.
They are all liquid at room temperature, unlike fats that are solid. The difference lies in the type of fatty acids that make up the oil.
UNDERSTANDING FATTY ACIDS
All fats and oils are made up of the same chemical elements built up into 'chains' called fatty acids. They differ, depending on the length of the chain and the type of bonding that occurs between the molecules of the chain. Chains can be of long, medium or short chain length. The bonds can either be single, forming saturated fatty acids (SFA) or double forming unsaturated fatty acids. If there is only one double bond in the chain, it is referred to as mono-unsaturated (MUFA) and if there are two or more double bonds, then it is called poly-unsaturated (PUFA). It is these two characteristics of fatty acids that determine how the fats and oils will be treated in the body.
CHOLESTEROL AND HEART DISEASE
None of the vegetable oils contain cholesterol, the substance associated with increased risk of heart disease, and none of itself will raise the level of blood cholesterol. The body produces its own cholesterol using any excess fats in the diet as a substrate. The fats preferred for this purpose are the long chain saturated fats of meats and other animal foods. Coconut oil, although saturated, contains predominantly medium chain-length fatty acids (MCFA) and these have not been found to raise cholesterol levels.
The other oils have long chain fatty acids but they are either mono-unsaturated like olive and peanut oils and neutral to cholesterol, or poly-unsaturated like corn and soy, which have been shown to lower cholesterol levels. Canola oil is a product modified for food use by replacing the original fatty acid by one high in monounsaturates. Whereas the original rapeseed oil was linked with heart disease the modified canola oil is not.
FREE RADICALS AND DIGESTIBILITY
There are other properties of oils that may influence your decision. The long chain fatty acids like corn and soy are more difficult to digest and absorb than the medium chain coconut oil, which is preferred for children and in situations of emaciation needing oils for added energy. Also, the many double bonds of corn are very reactive and will produce free radicals, the substances that can initiate cancerous reactions if left uncontrolled. This oil therefore requires more antioxidant nutrients such as vitamin E when used. Coconut oil, being already saturated, is not reactive and will not produce free radicals. It however, lacks the essential fatty acid, linoleic acid, which must be obtained from other plant sources to make a balanced diet.
OTHER CONSIDERATIONS
The MCFA of coconut oil have anti-infective and anti-inflammatory properties and therefore the preferred oil for HIV/AIDS and similar situations. Olive oil also has anti-infective effects useful for detoxification in the body.
Whichever oil you choose, remember that all types of fat carry the same calories i.e., 9 per gram, and excess can make the diet too high in energy thereby contributing to obesity and the associated chronic disorders such as diabetes, high blood pressure and heart conditions. Your total fat intake should not exceed thirty per cent of calories and the World Health Organisation recommends that this should be divided as 1/3 saturated, 1/3 mono-unsaturated and 1/3 poly-unsaturated.
Patricia Thompson M.Sc., registered nutritionist, nutrition and diet services; email: yourhealth@gleanerjm.com.
