How a Western diet prevents the flu

Many of us rely on the flu vaccine to stay in shape during the cold winter months.

But research suggests that the Western fat diet could hinder the effectiveness of the vaccine.

The scientists examined the effects of tert-butylhydroquinone (tBHQ), a food additive commonly found in cooking oils, frozen meat, chips and crackers, in mice.

They discovered that exposure to tBHQ reduced the number of cells that fight the virus in the body of rodents when they are fighting the flu.

And when the animals were exposed to the same virus later, their body was less able to recognize – and trigger an immune response against – the life-threatening pathogen.

The research was conducted by Michigan State University and directed by Robert Freeborn, a fourth-year PhD student in the Department of Pharmacology and Toxicology.

"If you get a vaccine, but a part of the immune system does not learn to recognize and fight off virus-infected cells, then the vaccine will be less effective," Freeborn said.

"We determined that the introduction of tBHQ through the diet affected certain cells that play an important role in the proper immune response to the flu."

The flu was responsible for nearly 650,000 respiratory-related deaths globally during the 2017/18 influenza season, the authors wrote in their presentation at the 2019 meeting on experimental biology.

In the United States alone, 79,000 people died of flu that season.

The researchers noted that flu mortality rates did not improve despite the increase in the number of people vaccinated against the virus.

They wondered if environmental factors could worsen the spread of the infection or reduce the effectiveness of the bite.

TBHQ is added to food to prolong its shelf life and it has been shown to reduce the activation of CD4 immune cells in laboratory models.

To test whether the same effect occurs in animals, the researchers added tBHQ to the mice in amounts comparable to those of the western diet.

This is worthless; the additive does not always appear in the list of ingredients of a product.

Two weeks after the start of the diet, the rodents were exposed to one of four influenza strains.

Ten days later, the researchers collected fluid from the animals' lungs and lymph nodes to measure their levels of CD4 and CD8 T cells, which make up the immune system.

"CD4 T cells are like movie directors telling everyone what to do," said Freeborn.

"The CD8 T cells are the actors who do what the director wants."

The results revealed that exposure to tBHQ impaired the ability of CD8 T cells to enter the lungs compared to mice fed a control diet.

TBHQ also slowed down the activation of T cells, which reduced their ability to fight infections earlier.

"Overall, we found a reduction in the number of CD8 T cells in the lungs and a reduction in the number of CD4 and CD8 T cells able to identify the influenza virus in mice exposed to tBHQ," he said. Mr. Freeborn.

"These mice also had generalized inflammation and mucous production in their lungs.

"Our studies have shown that tBHQ-treated mice have a weakened immune response to influenza infection.

& # 39; In our mouse model, tBHQ suppressed the function of two types of T cells, helper T cells and killer T cells.

"In the end, this led to more severe symptoms during a subsequent influenza infection."

In a second part of the study, researchers investigated whether tBHQ affected the ability of rodents to respond to an influenza strain they had known before.

The results revealed that the control diet mice began to show signs of recovery three days later.

But people exposed to tBHQ took twice as long, only starting to fight the infection on the sixth day.

"This suggests that tBHQ has altered the memory response to infection by related strains of the influenza virus, which could be correlated with reduced efficacy of vaccination," the authors wrote.

The tBHQ also brought the mice to lose more weight while fighting the infection.

"It's important that the body is able to recognize a virus and remember how to fight it effectively," said Mr. Freeborn.

"It's all about vaccines, to boost that memory and to produce immunity.

& # 39; tBHQ seems to hinder this process. & # 39;

Although we do not know exactly why this is happening, Dr. Freeborn believes that tBHQ "up-regulates certain proteins that are known to suppress the immune system."

His team plans to study the impact of the additive on human blood samples.

In the meantime, the best way to avoid these effects is to eliminate or minimize the tBHQ of your diet.

"It can be difficult to know if you are consuming tBHQ because it is not always indicated on ingredient labels," said Freeborn.

"Since tBHQ is widely used to stabilize fats, a low-fat diet and reduced processed snack foods will help reduce tBHQ consumption."

Freeborn also pointed out that the best way to protect against infection is to get the flu shot every year.