Fish Oil Reduces Chemotherapy Effectiveness

The research shows that all the six fish oil supplements tested contained a specific fatty acid that has been found to reduce the effectiveness of chemotherapy in mice.

According to Dr. Emile Voest from the Netherlands Cancer Institute in Amsterdam , people receiving chemotherapy should refrain from taking fish oil supplements and discuss any supplement with their doctors.

“I’m always discussing it with my patients,” he said. “Please have an open relationship with me and tell me what you’re taking.”

He and his colleagues said that omega-3 fatty acids are consumed by about a fifth of Americans with cancer – usually through fish oil.

Fish oil is often sold in capsules for about $10 or $11 for 100 pills.

The researchers had previously found that even a small amount of two fatty acids reduced the effectiveness of chemotherapy in mice with cancer.

‘These fatty acids may ultimately enable cancer cells to repair themselves faster after chemotherapy,’ Voest said.

Fatty acid levels elevated

When his team looked for the two fatty acids in six fish oil supplements, one was not detected but the fatty acid called 16:4(n-3) was ubiquitous.

The researchers also surveyed 400 people receiving treatment for cancer in November 2011.

Of 118 people who returned the surveys, 35 percent reported using nutritional supplements and 11 percent reported using omega-3 fatty acid supplements.

In another part of the study, the researchers had 30 volunteers without cancer take 10 or 50 milliliters (mL) of the three fish oil supplements.

Levels of 16:4(n-3) peaked in their blood about four hours after taking the 10 mL supplements; levels returned to normal after about eight hours.

Levels of the fatty acid remained elevated longer among those taking 50 mL.

Furthermore, when 20 volunteers ate mackerel or herring, levels of 16:4(n-3) in their blood went up.

However Eating salmon or tuna had little or no effect.

The researchers conclude that until more is known, people on chemotherapy should avoid fish oil – and herring and mackerel – the day before and after their treatments.

by Musalia Wycliffe.