Cod liver oil and fish oil are among the top 20 best-sellers in retail pharmacies in Jamaica. Of course, iron tablets, multivitamins and appetite stimulants (many Jamaicans want to get fat!) are right up there with them. Yes, Jamaicans, like so many people worldwide, are beefing up their diets with natural food supplements.

There are major differences between the cod liver oil and fish oils:

Source - Cod liver oil comes from the liver of cod-fish, while fish oil is really fish-flesh oil, from the flesh of oily cold-water, deep-sea fish, like salmon, mackerel and halibut. The fish from Jamaican waters and those raised on fish farms do not contain much fish oil, but we can get these oils from the fish-oil capsules.

Content - Cod liver oil is rich in vitamins A and D, great for our bones. It has a little vitamin E as well. Adults take three to six capsules daily. Cod liver oil liquid, although it tastes 'yucky', is more economical than capsules. The liquid supplies much more vitamins A and D per dose (and at a cheaper cost) than the capsules. Children over one year old may take two teaspoonfuls daily.

On the other hand, fish oil does not contain vitamins A and D, but contains plenty of omega-3 essential fatty acids; up to 300mg of combined omega-3 fatty acids per capsule. Under medical supervision, we may take up to 10 such fish oil capsules per day. Although cod liver oil has meagre amounts of omega-3 fatty acids, manufacturers, such as Seven Seas, have incorporated fish oil in their newer products.

What's the Use?

Cod liver oil is a useful supplement:

People with the wear-and-tear type of arthritis (osteo-arthritis) benefit from it.

The vitamin A is an anti-oxidant, enhancing the body's immunity and helps in maintenance and healing of skin and eyes.

Vitamin D helps us absorb and use calcium and phosphorus and helps in thyroid gland functioning and blood clotting. It is useful in children's bone and teeth development.

Fish oil and the omega-3 essential fatty acids it contains have a myriad of uses:

Fatty acids are building blocks for hormones and cell membranes.

It helps in the development of the brain and nervous system, may reduce the risk of Alzheimer's disease, and is useful in depression and bipolar disorder.

It reduces triglycerides, fat which is implicated in cardio-vascular diseases.

It improves blood circulation.

Fish oil supports the immune system and is used therapeutically in immune conditions like lupus and rheumatoid arthritis.

Fish oils and blood-thinning

Fish oil thins the blood. Excessive blood-thinning is dangerous. Before taking fish-oil supplements talk to a doctor or pharmacist, especially if you are already taking blood-thinning drugs like warfarin, aspirin, clopidogrel (Plavix), dipyridamole, or herbal supplements containing high doses of vitamin E, ginger and garlic. By the same token, we should approach fish oil with caution if we have blood-clotting disorders or diabetes.

Dahlia McDaniel is a pharmacist and final year doctoral candidate in public health at the University of London; email: yourhealth@gleanerjm.com.