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Spinach-rich diet may prevent colon cancer


September 29, 2021
By Texas A&M University

Eating spinach could prevent colon cancer, new research suggests.

In the United States, colon cancer is the fourth-most common cancer and second-leading cause of cancer-related deaths. Previous studies have shown that eating green vegetables and fiber reduces risk of colon cancer by as much as half.

The new study in the journal Gut Microbes explores the relationship between spinach, gut health, genes, and colon cancer outcomes.

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The researchers used a model of a hereditary disease called familial adenomatous polyposis, an inherited disorder that causes young people to develop multiple noncancerous growths (polyps) in their colon.

Most people with this disease must have their colon surgically removed to prevent hundreds of tumors from growing in their colon as they age. They then undergo often-toxic NSAYS treatment to prevent additional tumors from forming in the duodenum, the first part of the small intestine.

The new study’s findings indicate spinach might aid in cancer prevention in these patients by delaying the need for colon removal and prolonged drug treatment.

After feeding freeze-dried spinach to an animal model of familial adenomatous polyposis for 26 weeks, the researchers observed significant antitumor activity in the colon and small intestine. Using an unbiased approach called multi-omics, they found that the tumor suppression from spinach involved increased diversity in the gut microbiome (helpful microbes) and changes in gene expression to help prevent cancer.

The researchers also found that fatty acids associated with regulation of inflammation, called linoleate metabolites, were brought up to a beneficial level after a spinach diet.

“We believe eating spinach can also be protective for people who do not have familial adenomatous polyposis,” says principal investigator Roderick Dashwood, director of the Center for Epigenetics & Disease Prevention at the Texas A&M University Health Institute of Biosciences and Technology.

Hereditary forms of colon cancer only account for about 10 to 15% of cases. The majority of colon cancers are sporadic, meaning they are not driven by a genetic predisposition inherited through a family. Over decades, exposure to carcinogens through diet and environment can change the way genes are expressed in the gastrointestinal (GI) tract, and this can cause people to develop polyps in the colon and lower GI tract later in life that can progress into cancer, Dashwood says. This is why the American Cancer Society recommends starting colon cancer screening at age 45.

Dashwood’s lab previously noticed the benefits of spinach in a carcinogen-induced model of colorectal cancer that mimics sporadic cases. In that model, spinach was very effective in preventing polyps, which spurred the team to see how spinach might work in colon cancer driven by genetics.

“My bias was to focus on the chlorophyll story because of my long history examining anti-cancer effects of chlorophyll,” Dashwood says. “But it turned out the multi-omics approach prompted other ideas. When we looked at the metabolomic data, there was no chlorophyll. It was actually fatty acids and linoleic acid derivatives that were causing the beneficial effects.”

Multi-omics allows scientists to carefully analyze biological “big data” to find associations between different systems in the body, pinpoint biomarkers, and better understand the complex interrelationships that drive life.

Instead of traditional hypothesis-driven research, multi-omics is a hypothesis-generating approach in which scientists follow the data to land at explanations for results. The three omics used in this study were microbiome (helpful and harmful microbes), transcriptome (gene expression), and metabolome (metabolites, such as amino acids and fatty acids). The word “omics” comes from the “ome” in these words.

To crunch the metabolome data, Dashwood’s team used the Integrated Metabolomics Analysis Core facility established by Arul Jayaraman at the Texas A&M College of Engineering. First author Ying-Shiuan Chen worked closely with Jayaraman and his team for two years to analyze the hundreds of samples collected from the study’s models.

“This is one of the most comprehensive metabolomics analyses of its kind, especially in the context of cancer prevention by a whole food, spinach,” says Jayaraman, head of the department of chemical engineering at the College of Engineering.

The next step for the team is to validate some of the metabolomic aspects of their findings, such as concentrations of linoleic acid metabolites and short chain fatty acids with anticancer effects on the preclinical model, and ideally in human patients.

When it comes to how soon people should start adding spinach into their diet to help prevent colon cancer, it doesn’t hurt to start now.

“The sooner the better,” Dashwood says. “You shouldn’t wait until polyps arise in order to start to do these sorts of preventive things.”

Original Study DOI: 10.1080/19490976.2021.1972756


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