Conjugated linoleic acid (CLA)
Conjugated linoleic acid, or CLA, refers to a group of chemicals found in the fatty acid linoleic acid.
Dairy products and beef are the major dietary sources.
Conjugated linoleic acid has been studied for use in many conditions, including cancer, hardening and narrowing of the arteries ( atherosclerosis), obesity, weight loss, bodybuilding and limiting allergy reactions.
To date, no scientific evidence has confirmed that it can help with these conditions.
In order for a product to be sold making nutritional health claims, scientific proof has to be assessed by the European Food Safety Agency. No such claims for conjugated linoleic acid have been authorised yet.
How does it work?
Conjugated linoleic acid might help reduce body fat deposits and improve immune function.
However, more research is needed.
There is insufficient evidence that it is useful for bodybuilding or reducing cholesterol levels.
Conjugated linoleic acid caution
Conjugated linoleic acid is thought to be safe in amounts found in food.
In larger amounts it might cause side effects such as stomach upset, diarrhoea, nausea and fatigue.
Not enough evidence is known on whether conjugated linoleic acid is safe during pregnancy and breast-feeding.
The NHS says one reported side-effect of taking conjugated linoleic acid is insulin resistance, affecting people with diabetes. It may also increase the risk of diabetes for people with metabolic syndrome.