Food dyes might make food look more appealing, but their safety has long been controversial. New research from the University of Guelph reveals an unexpected way these compounds may be harming health: by disrupting the microbial communities in the gut.
In two new recently published papers, researchers from the College of Biological Science found that commonly used food dyes can break down in the gut to create potentially toxic byproducts.
Our gut microbiomes contain bacteria, fungi and other microbes that help break down food and stimulate our immune systems. Imbalances between good and bad microbes have been shown to result in several health issues, says Dr. Emma Allen-Vercoe, professor in the Department of Molecular and Cellular Biology (MCB).
“I don’t think that anyone realizes how fragile the gut microbiome is,” says Allen-Vercoe, Canada Research Chair in Human Gut Microbiome Function and Host Interactions.
“Why are so many of us missing certain microbes, and how did we lose them? One potential reason is all the artificial stuff we put into our food, including food colourants, which few people have looked at.”
Allen-Vercoe, along with MCB colleague and biochemist Dr. David Josephy, set out to address this knowledge gap by investigating azo food dyes, the class of synthetic dyes commonly used in food, drugs and cosmetics.
Allen-Vercoe’s team wanted to investigate how bacteria in the human gut metabolize or “reduce” azo dyes, and how the resulting compounds impact the growth of gut bacteria.
Four azo dyes are currently approved for human consumption in Canada: amaranth, sunset yellow, allura red and tartrazine. Many others are banned as a result of unacceptable toxicity.
Food dyes’ interaction with gut microbiome not well tested
The food dyes included in the research were amaranth, allura red, sunset yellow, and tartrazine
While azo dyes have been tested for effects on animal cells, where they tend to be inert, theirinteractions with microbial cells have been mostly ignored and were not considered in the drafting of current food dye use regulations. That’s despite the fact that there is evidence azo dyes can be reduced by gut bacteria to create new metabolites that may be toxic.
“Bacteria in particular have had many eons longer than we have had to evolve. Consequently, they are incredible biochemists and azo dye reduction is not difficult for them” says Allen-Vercoe.
To evaluate the response of gut microbes to the four azo dyes, Allen-Vercoe’s team grew over 124 human gut bacterial species in culture media infused with one of the four approved dyes.
Any bacterial strains that could break down the dyes – as revealed by the disappearance of colour from the growth medium – were further tested to assess how well they functioned amid the breakdown products of azo dye reduction.
The study, published in the journal Anaerobe, revealed that many of the bacterial species typically found in the human gut could extensively reduce the dyes.
Amaranth was reduced the most frequently by gut bacteria, while tartrazine was reduced the least, although still by a substantial number of strains. In many cases, different strains of the same gut bacterial species showed variability in their reductive capabilities.
Food dye regulations outdated, say researchers
Molecular biologist Dr. Emma Allen-Vercoe has been researching the effects of synthetic food dyes on the gut microbiome.
The team also found contrasting growth responses of gut bacteria upon exposure to azo dyes and their breakdown products. Some gut bacteria increased in growth while for others, growth was inhibited. For example, bacterial reduction of sunset yellow and tartrazine led to the formation of sulfanilic acid which was toxic to some bacterial species.
The findings might help explain why some people are more sensitive to azo food dyes than others. Everyone has a unique gut microbiome, and thus some people may harbour more microbes that reduce azo dyes to toxic metabolites, compared to others.
The team also conducted a second collaborative study with colleagues in New Zealand, published in the journal Food and Chemical Toxicology, focusing solely on tartrazine. That study further revealed the reduction products of the dye in the gut and their toxic impacts on host cells.
Allen-Vercoe says the studies emphasize the need for food dye regulations to be updated to include the latest findings. She notes that most of the current regulations are based on research from the 1950s and ‘60s that considered only the effects of the dyes on animal cells, and not the way the compounds are metabolized in the gut.
She adds that the risks from azo dyes concern her. “If I were able to listen to my gut microbes, they would tell me to stop consuming artificially coloured foods.”
Synthetic food colourings such as azo dyes contain no nutritious qualities, she points out, and are added to food simply to make it look more attractive.
“We need the food industry to quickly get on board with this research and, ultimately, to remove azo dyes and other artificial colours from their products.”
This research was funded by the Canada Research Chair program and the New Zealand Royal Society.
Written by Sujani Rathnayake. Sujani is a writer with SCRIBE, a program for graduate students in the College of Biological Science to gain paid experience in translating research results for a non-specialist audience.
HALIFAX – The Nova Scotia government says it could be months before it reveals how many people are on the wait-list for a family doctor.
The head of the province’s health authority told reporters Wednesday that the government won’t release updated data until the 160,000 people who were on the wait-list in June are contacted to verify whether they still need primary care.
Karen Oldfield said Nova Scotia Health is working on validating the primary care wait-list data before posting new numbers, and that work may take a matter of months. The most recent public wait-list figures are from June 1, when 160,234 people, or about 16 per cent of the population, were on it.
“It’s going to take time to make 160,000 calls,” Oldfield said. “We are not talking weeks, we are talking months.”
The interim CEO and president of Nova Scotia Health said people on the list are being asked where they live, whether they still need a family doctor, and to give an update on their health.
A spokesperson with the province’s Health Department says the government and its health authority are “working hard” to turn the wait-list registry into a useful tool, adding that the data will be shared once it is validated.
Nova Scotia’s NDP are calling on Premier Tim Houston to immediately release statistics on how many people are looking for a family doctor. On Tuesday, the NDP introduced a bill that would require the health minister to make the number public every month.
“It is unacceptable for the list to be more than three months out of date,” NDP Leader Claudia Chender said Tuesday.
Chender said releasing this data regularly is vital so Nova Scotians can track the government’s progress on its main 2021 campaign promise: fixing health care.
The number of people in need of a family doctor has more than doubled between the 2021 summer election campaign and June 2024. Since September 2021 about 300 doctors have been added to the provincial health system, the Health Department said.
“We’ll know if Tim Houston is keeping his 2021 election promise to fix health care when Nova Scotians are attached to primary care,” Chender said.
This report by The Canadian Press was first published Sept. 11, 2024.
ST. JOHN’S, N.L. – Newfoundland and Labrador‘s chief medical officer is monitoring the rise of whooping cough infections across the province as cases of the highly contagious disease continue to grow across Canada.
Dr. Janice Fitzgerald says that so far this year, the province has recorded 230 confirmed cases of the vaccine-preventable respiratory tract infection, also known as pertussis.
Late last month, Quebec reported more than 11,000 cases during the same time period, while Ontario counted 470 cases, well above the five-year average of 98. In Quebec, the majority of patients are between the ages of 10 and 14.
Meanwhile, New Brunswick has declared a whooping cough outbreak across the province. A total of 141 cases were reported by last month, exceeding the five-year average of 34.
The disease can lead to severe complications among vulnerable populations including infants, who are at the highest risk of suffering from complications like pneumonia and seizures. Symptoms may start with a runny nose, mild fever and cough, then progress to severe coughing accompanied by a distinctive “whooping” sound during inhalation.
“The public, especially pregnant people and those in close contact with infants, are encouraged to be aware of symptoms related to pertussis and to ensure vaccinations are up to date,” Newfoundland and Labrador’s Health Department said in a statement.
Whooping cough can be treated with antibiotics, but vaccination is the most effective way to control the spread of the disease. As a result, the province has expanded immunization efforts this school year. While booster doses are already offered in Grade 9, the vaccine is now being offered to Grade 8 students as well.
Public health officials say whooping cough is a cyclical disease that increases every two to five or six years.
Meanwhile, New Brunswick’s acting chief medical officer of health expects the current case count to get worse before tapering off.
A rise in whooping cough cases has also been reported in the United States and elsewhere. The Pan American Health Organization issued an alert in July encouraging countries to ramp up their surveillance and vaccination coverage.
This report by The Canadian Press was first published Sept. 10, 2024.
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