APR 23, 2021 12:14 PM PDT

A Causal Connection Between C-Section Births & Food Allergies

WRITTEN BY: Carmen Leitch

The microorganisms that live in the human gut have a powerful influence on our health, and that microbial community is with us since birth, maybe even before that. A person's microbiome is also known to be affected by how they are delivered. Researchers are learning more about how changes in the gut microbiome in early life can have a lasting impact. Now, researchers have shown that delivery by cesarean section (C-section), low levels of gut microbes, and peanut sensitivity are causally linked. This effect also seems to be more prevalent among kids of Asian descent. The findings have been reported in Gastroenterology.

Bacteroides hypermegas after being cultured in a thioglycollate medium for a 48 hour time period. / Credit: CDC/ Dr. V. R. Dowell, Jr.

"It's important to know what predicts or increases [the] risk of food sensitivities because they predict which infants will go on to develop asthma and other types of allergies," noted senior study author Anita Kozyrskyj, a pediatrics professor at the University of Alberta's Faculty of Medicine & Dentistry.

In this work, the researchers used stool samples to assess the gut microbes of 1,422 infants enrolled in the CHILD Cohort Study; the samples were taken when the kids were around three or four months old and then again at twelve months. The children also got skin pricks at one and three years old to determine their allergen sensitivity to stuff like milk, eggs, and peanuts.

The study revealed four typical profiles of development in the infants' microbiomes. In one profile that was most common among babies born by C-section, there were persistently low levels of a type of bacteria called Bacteriodes, a bacterial species that's thought to be crucial to the development of the immune system. In children with low Bacteroides levels, the risk of developing a peanut sensitivity by the age of three was increased three-fold. In children of Asian descent, the risk went up eight-fold. There were also lower levels of proteins called sphingolipids that are involved in cell signaling, including in the immune system. These proteins tend to come from gut bacteria.

Statistical tools can sometimes help researchers differentiate between things that are linked, and things that have a cause-and-effect connection.

"In this case, we observed that there was an association between Asian ethnicity and peanut sensitivity, and then the mediation analysis provided additional evidence for the causal association with cesarean section," explained Kozyrskyj. She also noted that children that have a sphingolipid deficiency in immune cells might be more likely to develop food allergies.

"As the gut microbiota are developing so is the gut's immune system, training the gut to react to pathogens and to be tolerant of the food that we require," she explained.

Food allergy rates are increasing in western countries, which Kozyrskyj suggested is probably due to environmental factors. "In China food allergies are uncommon, but those who immigrate to Canada face a higher risk and more severe form of allergic disease," she said. "It's likely related to a change in diet and environment."

Now the research has to be replicated, she noted.

Tests assessing the efficacy of vaginal swabs or probiotic treatments after C-section birth have not been successful. For now, it may be important to avoid C-sections unless they are medically necessary. "With this evidence at hand, the parent and the obstetrician might choose a different birth mode," she said.

Sources: Science Daily via University of Alberta Faculty of Medicine & Dentistry, Gastroenterology

About the Author
  • Experienced research scientist and technical expert with authorships on over 30 peer-reviewed publications, traveler to over 70 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
OCT 13, 2021
Chemistry & Physics
The Nobel Prize in Chemistry
OCT 13, 2021
The Nobel Prize in Chemistry
It's Nobel Prize season, and the third to be awarded was in the field of Chemistry. The winners were two men working on ...
OCT 27, 2021
Microbiology
Revealing the Helpful or Acne-Causing Microbes on Human Skin
OCT 27, 2021
Revealing the Helpful or Acne-Causing Microbes on Human Skin
Acne is a complex condition, and the biological processes underlying the formation of pimples are not fully understood. ...
NOV 01, 2021
Cancer
Gut Microbiota Promotes Resistance to Prostate Cancer Therapy
NOV 01, 2021
Gut Microbiota Promotes Resistance to Prostate Cancer Therapy
  The American Cancer Society estimates that nearly 250,000 men in the United States will be diagnosed with prostat ...
NOV 07, 2021
Microbiology
Studying the Genetic Impact of a Common Viral infection
NOV 07, 2021
Studying the Genetic Impact of a Common Viral infection
Human cytomegalovirus (HCMV) infects many people; it's been estimated that by the time people are adults, about half of ...
NOV 17, 2021
Microbiology
Large Flu Outbreak at the University of Michigan Draws CDC's Attention
NOV 17, 2021
Large Flu Outbreak at the University of Michigan Draws CDC's Attention
Every year, there is a flu outbreak, and the severity can depend on many factors, like what strain is circulating. Last ...
DEC 03, 2021
Genetics & Genomics
Using CRISPR to Edit the Genomes of Microbes in the Gut
DEC 03, 2021
Using CRISPR to Edit the Genomes of Microbes in the Gut
The gene editing tool CRISPR was originally inspired by an immune defense system used by bacteria, and it's been adapted ...
Loading Comments...