Does intermittent fasting increase or decrease our risk of cancer?

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Research over the years has suggested intermittent fasting has the potential to improve our health and reduce the likelihood of developing cancer.

So what should we make of a new study in mice suggesting fasting increases the risk of cancer?

Stock-Asso/Shutterstock

What is intermittent fasting?

Intermittent fasting means switching between times of eating and not eating. Unlike traditional diets that focus on what to eat, this approach focuses on when to eat.

There are lots of commonly used intermittent fasting schedules. The 16/8 plan means you only eat within an eight-hour window, then fast for the remaining 16 hours. Another popular option is the 5:2 diet, where you eat normally for five days then restrict calories for two days.

In Australia, poor diet contributes to 7% of all cases of disease, including coronary heart disease, stroke, type 2 diabetes, and cancers of the bowel and lung. Globally, poor diet is linked to 22% of deaths in adults over the age of 25.

Intermittent fasting has gained a lot of attention in recent years for its potential health benefits. Fasting influences metabolism, which is how your body processes food and energy. It can affect how the body absorbs nutrients from food and burns energy from sugar and fat.

What did the new study find?

The new study, published in Nature, found when mice ate again after fasting, their gut stem cells, which help repair the intestine, became more active. The stem cells were better at regenerating compared with those of mice who were either totally fasting or eating normally.

This suggests the body might be better at healing itself when eating after fasting.

However, this could also have a downside. If there are genetic mutations present, the burst of stem cell-driven regeneration after eating again might make it easier for cancer to develop.

Polyamines – small molecules important for cell growth – drive this regeneration after refeeding. These polyamines can be produced by the body, influenced by diet, or come from gut bacteria.

The findings suggest that while fasting and refeeding can improve stem cell function and regeneration, there might be a tradeoff with an increased risk of cancer, especially if fasting and refeeding cycles are repeated over time.

While this has been shown in mice, the link between intermittent fasting and cancer risk in humans is more complicated and not yet fully understood.

What has other research found?

Studies in animals have found intermittent fasting can help with weight loss, improve blood pressure and blood sugar levels, and subsequently reduce the risks of diabetes and heart disease.

Research in humans suggests intermittent fasting can reduce body weight, improve metabolic health, reduce inflammation, and enhance cellular repair processes, which remove damaged cells that could potentially turn cancerous.

However, other studies warn that the benefits of intermittent fasting are the same as what can be achieved through calorie restriction, and that there isn’t enough evidence to confirm it reduces cancer risk in humans.

What about in people with cancer?

In studies of people who have cancer, fasting has been reported to protect against the side effects of chemotherapy and improve the effectiveness of cancer treatments, while decreasing damage to healthy cells.

Prolonged fasting in some patients who have cancer has been shown to be safe and may potentially be able to decrease tumour growth.

On the other hand, some experts advise caution. Studies in mice show intermittent fasting could weaken the immune system and make the body less able to fight infection, potentially leading to worse health outcomes in people who are unwell. However, there is currently no evidence that fasting increases the risk of bacterial infections in humans.

So is it OK to try intermittent fasting?

The current view on intermittent fasting is that it can be beneficial, but experts agree more research is needed. Short-term benefits such as weight loss and better overall health are well supported. But we don’t fully understand the long-term effects, especially when it comes to cancer risk and other immune-related issues.

Since there are many different methods of intermittent fasting and people react to them differently, it’s hard to give advice that works for everyone. And because most people who participated in the studies were overweight, or had diabetes or other health problems, we don’t know how the results apply to the broader population.

For healthy people, intermittent fasting is generally considered safe. But it’s not suitable for everyone, particularly those with certain medical conditions, pregnant or breastfeeding women, and people with a history of eating disorders. So consult your health-care provider before starting any fasting program.

Amali Cooray, PhD Candidate in Genetic Engineering and Cancer, WEHI (Walter and Eliza Hall Institute of Medical Research)

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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  • How a Friend’s Death Turned Colorado Teens Into Anti-Overdose Activists

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    Gavinn McKinney loved Nike shoes, fireworks, and sushi. He was studying Potawatomi, one of the languages of his Native American heritage. He loved holding his niece and smelling her baby smell. On his 15th birthday, the Durango, Colorado, teen spent a cold December afternoon chopping wood to help neighbors who couldn’t afford to heat their homes.

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    Naloxone is an opioid antagonist that can halt an overdose. Available over the counter as a nasal spray, it is considered the fire extinguisher of the opioid epidemic, for use in an emergency, but just one tool in a prevention strategy. (People often refer to it as “Narcan,” one of the more recognizable brand names, similar to how tissues, regardless of brand, are often called “Kleenex.”)

    The Biden administration last year backed an ad campaign encouraging young people to carry the emergency medication.

    Most states’ naloxone access laws protect do-gooders, including youth, from liability if they accidentally harm someone while administering naloxone. But without school policies explicitly allowing it, the students’ ability to bring naloxone to class falls into a gray area.

    Ryan Christoff said that in September 2022 fellow staff at Centaurus High School in Lafayette, Colorado, where he worked and which one of his daughters attended at the time, confiscated naloxone from one of her classmates.

    “She didn’t have anything on her other than the Narcan, and they took it away from her,” said Christoff, who had provided the confiscated Narcan to that student and many others after his daughter nearly died from fentanyl poisoning. “We should want every student to carry it.”

    Boulder Valley School District spokesperson Randy Barber said the incident “was a one-off and we’ve done some work since to make sure nurses are aware.” The district now encourages everyone to consider carrying naloxone, he said.

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    In Durango, McKinney’s death hit the community hard. McKinney’s friends and family said he didn’t do hard drugs. The substance he was hooked on was Tapatío hot sauce — he even brought some in his pocket to a Rockies game.

    After McKinney died, people started getting tattoos of the phrase he was known for, which was emblazoned on his favorite sweatshirt: “Love is the cure.” Even a few of his teachers got them. But it was classmates, along with their friends at another high school in town, who turned his loss into a political movement.

    “We’re making things happen on behalf of him,” Peterson said.

    The mortality rate has spiked in recent years, with more than 1,500 other children and teens in the U.S. dying of fentanyl poisoning the same year as McKinney. Most youth who die of overdoses have no known history of taking opioids, and many of them likely thought they were taking prescription opioids like OxyContin or Percocet — not the fake prescription pills that increasingly carry a lethal dose of fentanyl.

    “Most likely the largest group of teens that are dying are really teens that are experimenting, as opposed to teens that have a long-standing opioid use disorder,” said Joseph Friedman, a substance use researcher at UCLA who would like to see schools provide accurate drug education about counterfeit pills, such as with Stanford’s Safety First curriculum.

    Allowing students to carry a low-risk, lifesaving drug with them is in many ways the minimum schools can do, he said.

    “I would argue that what the schools should be doing is identifying high-risk teens and giving them the Narcan to take home with them and teaching them why it matters,” Friedman said.

    Writing in The New England Journal of Medicine, Friedman identified Colorado as a hot spot for high school-aged adolescent overdose deaths, with a mortality rate more than double that of the nation from 2020 to 2022.

    “Increasingly, fentanyl is being sold in pill form, and it’s happening to the largest degree in the West,” said Friedman. “I think that the teen overdose crisis is a direct result of that.”

    If Colorado lawmakers approve the bill, “I think that’s a really important step,” said Ju Nyeong Park, an assistant professor of medicine at Brown University, who leads a research group focused on how to prevent overdoses. “I hope that the Colorado Legislature does and that other states follow as well.”

    Park said comprehensive programs to test drugs for dangerous contaminants, better access to evidence-based treatment for adolescents who develop a substance use disorder, and promotion of harm reduction tools are also important. “For example, there is a national hotline called Never Use Alone that anyone can call anonymously to be supervised remotely in case of an emergency,” she said.

    Taking Matters Into Their Own Hands

    Many Colorado school districts are training staff how to administer naloxone and are stocking it on school grounds through a program that allows them to acquire it from the state at little to no cost. But it was clear to Peterson and other area high schoolers that having naloxone at school isn’t enough, especially in rural places.

    “The teachers who are trained to use Narcan will not be at the parties where the students will be using the drugs,” he said.

    And it isn’t enough to expect teens to keep it at home.

    “It’s not going to be helpful if it’s in somebody’s house 20 minutes outside of town. It’s going to be helpful if it’s in their backpack always,” said Zoe Ramsey, another of McKinney’s friends and a senior at Animas High School.

    “We were informed it was against the rules to carry naloxone, and especially to distribute it,” said Ilias “Leo” Stritikus, who graduated from Durango High School last year.

    But students in the area, and their school administrators, were uncertain: Could students get in trouble for carrying the opioid antagonist in their backpacks, or if they distributed it to friends? And could a school or district be held liable if something went wrong?

    He, along with Ramsey and Peterson, helped form the group Students Against Overdose. Together, they convinced Animas, which is a charter school, and the surrounding school district, to change policies. Now, with parental permission, and after going through training on how to administer it, students may carry naloxone on school grounds.

    Durango School District 9-R spokesperson Karla Sluis said at least 45 students have completed the training.

    School districts in other parts of the nation have also determined it’s important to clarify students’ ability to carry naloxone.

    “We want to be a part of saving lives,” said Smita Malhotra, chief medical director for Los Angeles Unified School District in California.

    Los Angeles County had one of the nation’s highest adolescent overdose death tallies of any U.S. county: From 2020 to 2022, 111 teens ages 14 to 18 died. One of them was a 15-year-old who died in a school bathroom of fentanyl poisoning. Malhotra’s district has since updated its policy on naloxone to permit students to carry and administer it.

    “All students can carry naloxone in our school campuses without facing any discipline,” Malhotra said. She said the district is also doubling down on peer support and hosting educational sessions for families and students.

    Montgomery County Public Schools in Maryland took a similar approach. School staff had to administer naloxone 18 times over the course of a school year, and five students died over the course of about one semester.

    When the district held community forums on the issue, Patricia Kapunan, the district’s medical officer, said, “Students were very vocal about wanting access to naloxone. A student is very unlikely to carry something in their backpack which they think they might get in trouble for.”

    So it, too, clarified its policy. While that was underway, local news reported that high school students found a teen passed out, with purple lips, in the bathroom of a McDonald’s down the street from their school, and used Narcan to revive them. It was during lunch on a school day.

    “We can’t Narcan our way out of the opioid use crisis,” said Kapunan. “But it was critical to do it first. Just like knowing 911.”

    Now, with the support of the district and county health department, students are training other students how to administer naloxone. Jackson Taylor, one of the student trainers, estimated they trained about 200 students over the course of three hours on a recent Saturday.

    “It felt amazing, this footstep toward fixing the issue,” Taylor said.

    Each trainee left with two doses of naloxone.

    This article was produced by KFF Health News, which publishes California Healthline, an editorially independent service of the California Health Care Foundation. 

    KFF Health News is a national newsroom that produces in-depth journalism about health issues and is one of the core operating programs at KFF—an independent source of health policy research, polling, and journalism. Learn more about KFF.

    Subscribe to KFF Health News’ free Morning Briefing.

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