Scientists have discovered how eating oily fish can reduce the risk of heart attacks and strokes by balancing the concentration of fats and cholesterol in the blood.

The results come from samples taken from 26,034 women in the largest and most detailed study carried out.

Omega-3, the fatty acids present in fish, can regulate the body’s lipoproteins, the particles that transport lipids, or fat, through the blood, which reduces the risk of a person suffering cardiovascular events.

The benefits of consuming omega-3, in fish or in supplement form has been well-documented and has been crucial in fighting the prevalence of heart disease, which is the cause of one in three deaths from cardiovascular events.

High consumption of omega-3 has long been associated with lower levels of triglycerides, a type of fat in the blood created by the body converting any calories you do not need.

However it has also been related to increase in “bad cholesterol” – the low-density cholesterol carried around the body by lipoproteins.

LDL cholesterol, as it is known, increases the risk of heart disease because it can accelerate the formation of atherosclerosis – the process by which arteries harden and lose their elasticity.

But new research from Harvard Medical School and the Universitat Rovira Virgili in Tarragona, Spain, found increased consumption of 'bad cholesterol' from fish is primarily associated with the largest LDL particles, which are less likely to cause atherosclerosis.

This decrease in the number of triglycerides transported by any type of lipoprotein helps protect the individual from heart disease.

The three types of omega-3 fatty acids studied - linoleic acid, docosahexaenoic acid and eicosapentaenoic acid - are present in fish and are essential to human physiology.

The research found these fatty acids all differ in their association with the risk of cardiovascular disease.

Scientists revealed consuming omega-3 does not spark any increase in the smallest LDL lipoproteins that transport cholesterol.

Instead, the increase was among the largest LDL lipoproteins, which are not associated with the risk of heart disease.

On the other hand, eating fish caused a decrease in all of the triglyceride-transporting particles and an increase in the average size of the HDL and LDL particles, a phenomenon associated with increased protection from cardiovascular illness.

The researchers used mathematical modelling of the consumption of fish and omega-3, and the profile of lipoproteins.

Lead author Dr Nuria Amigo, chief executive of Biosfer Teslab, a spin-off of the Universitat Rovira Virgili, said: “Among the LDL particles that transport cholesterol it is the smallest that are associated with a future cardiovascular event.

“Having confirmed the risk factor associated with lipids, cholesterol concentration, triglycerides and the different subtypes of particles is modulated by the consumption of omega 3 fatty acids, we now need to find out if the consumption of fish is associated with lower mortality from both cardiovascular diseases and other causes.

“Although the risk is lower in terms of lipids, we need to look at other pro-inflammatory factors and questions such as exposure to heavy metals."