Fatty liver because of fish oil?

Long-term consumption of fish oil or sunflower oil may increase the risk of fatty liver disease later in life.

Research in mice shows that long-term consumption of sunflower oil or fish oil leads to changes in the liver that make the organ more susceptible to non-alcoholic steatohepatitis (NASH).

NASH is a serious form of non-alcoholic fatty liver disease (NAFLD).

Study co-author José Luis Quiles, a professor of physiology at the University of Granada in Spain, and colleagues recently reported their findings in The Journal of Nutritional Biochemistry.

It is estimated that about 20% of Americans with NAFLD also have NASH, and the disease becomes more common with age.

NASH is characterized by fat accumulation in the liver—not caused by alcohol consumption—inflammation and damage to liver cells. The liver damage that occurs in NASH can increase the risk of cirrhosis and liver cancer.

Some of the major risk factors for NASH include being overweight and obese, high blood pressure, high cholesterol, and type 2 diabetes, all of which are greatly influenced by diet.

How does dietary fat affect the liver?

Building on the link between diet and NASH, new research suggests that the type of cooking oil we use may play a role in our risk of developing the disease later in life.

Researchers came to this conclusion after analyzing the effects of different types of dietary fats, including sunflower oil, fish oil and olive oil, on the livers of mice.

Specifically, they looked at the effects of lifelong consumption of each oil on liver structure, as well as effects on gene expression, liver fibrosis, oxidative stress, and telomere length.

Oxidative stress is defined as an imbalance between free radicals — molecules that can damage cells — and the body's ability to "deoxidize" these molecules and prevent their harmful effects.

Telomeres are the "caps" at the ends of each DNA strand that protect chromosomes. The shorter the telomeres, the more cell damage there is.

Research has shown that reduced telomere length plays a key role in cellular aging and age-related disease. However, excessively long telomeres may increase the risk of cancer.

In addition, the team looked at age-related changes in liver function under the influence of different types of dietary fat.

Olive Oil is Best for a Healthy Liver

Not only do researchers find that fat accumulates in the liver with age, but the type of fat that accumulates in the liver is also influenced by the type of fat we eat.

Research shows that fish oil and sunflower oil negatively affect liver health in rats.

Long-term intake of sunflower oil triggers liver fibrosis, and it also changes the structure of this organ, leading to changes in gene expression, and increased oxidation in liver cells.

Mice fed fish oil for long periods of time showed age-related increases in cellular oxidation in the liver, and they also had reduced activity of the electron transport chain in mitochondria — the cell's "powerhouse" — impairing cell function.

Fish oil also resulted in a relative increase in telomere length in the liver. However, olive oil was found to cause the least liver damage.

These findings suggest that extra virgin olive oil may be the best fat for future liver health.

"The changes caused by long-term consumption of sunflower oil and fish oil make people more susceptible to non-alcoholic steatohepatitis, a very serious disease that can act as a catalyst for other liver diseases such as cirrhosis and liver cancer. We believe that this research will be very useful in preventing and treating many different forms of liver disease," said Professor José Luis Quiles.

Extra virgin olive oil is a proven healthful choice across many different aspects of health."

These findings may come as a surprise; fish oil is the most commonly used natural product in the United States due to its frequently documented health benefits.

However, this latest research should definitely give you something to think about when choosing which fats to include in your diet.