FIBER It Does a Body Good
Fiber and Cancer Prevention: Why It Matters
Should you be eating more fiber to help prevent cancer? And how much do you really need to reduce your risk?
It could be time for a fiber tune-up of your diet. Most American adults get only half the recommended daily dose, according to the Centers for Disease Control and Prevention (CDC).
Clinical dietitian-nutritionist Cara Anselmo, MS, RDN, is an expert in breast cancer nutrition and is a certified specialist in obesity and weight management.
“Eating more fiber is often overlooked as one of the healthiest things we can do for ourselves,” Anselmo says.
Fiber not only improves heart health, reduces diabetes risk, and aids in weight control, it may reduce the risk of several common cancers such as colorectal cancer.
How Does Fiber Reduce the Risk of Colorectal Cancer?
Dietary fiber has long been linked to a lower risk of certain types of cancer, particularly colorectal cancer. Colon cancer rates are increasing among young adults. Because less than 10% of adults are getting enough fiber, scientists think this trend may be connected.
One of the main ways that fiber helps to protect against colon cancer, according to Anselmo, is by fostering a healthy population of bacteria in the colon, known as the microbiome. Fiber remains in the colon after other components of the diet become absorbed by the body.
“When fiber is fermented by the bacteria in our colon,” Anselmo says, “it produces metabolites, which reduce inflammation and protect the colon cells from becoming cancerous. These metabolites can also activate our immune system and increase anti-cancer immunity.”
Fiber also has several other effects that improve our metabolic health, which indirectly lowers the risk of several cancers. For example, fiber can increase the speed at which food passes through the gut, which can lower absorption and exposure time to less healthy foods we may have consumed. Fiber can also lower cholesterol levels.
What Is a High-Fiber Diet?
A high-fiber diet means you eat foods that are rich in this type of carbohydrate, found mainly in plant foods such as fruits, vegetables, whole grains, beans, peas, and legumes. Consuming more than 25 to 30 grams of fiber per day is generally considered to be a high-fiber diet.
What Are the Kinds of Fiber?
There are two main types of dietary fiber — soluble and insoluble. Both types of fiber are healthy and can lower cancer risk.
Soluble fiber attracts water into the intestines and becomes a gel. It can help lower blood sugar and cholesterol levels. Foods higher in soluble fiber include:
• Oats
• Beans
• Citrus fruits
• Peas
Insoluble fiber doesn’t dissolve in water. It can help move food through your digestive system, absorb water to provide bulk, and may help prevent constipation. Foods higher in insoluble fiber include:
• Whole grains
• Some vegetables
• Nuts and seeds
How Much Fiber Do You Need?
The MSK registered dietitian-nutritionist team recommends that most people eat 25 grams of fiber per day. “Consume half of your fiber from whole foods like whole grains, vegetables, and beans,” Anselmo advises. “Fiber-supplemented products are not as effective as whole foods and may not have additional nutrients that help you reach your optimal health.”
Anselmo also stresses the importance of staying well hydrated when increasing dietary fiber in order to minimize potential symptoms such as bloating and abdominal discomfort as your gastrointestinal tract adapts to new changes. She reminds patients to always ask their cancer care team if they should follow any special diet before, during, or after treatment.
How Is MSK Researching the Role of Fiber and Cancer?
Studies are underway to help determine a person’s optimal dose of fiber to prevent cancer, based on their biology, genetics, and lifestyle.
MSK is also investigating which bacteria are involved in fermenting fiber into the metabolites that protect against various cancers, including breast, skin, prostate, colon, and rectal cancer. If scientists can identify a specific bacterial signature, other interventions such as bacterial transplants may work to reduce cancer risks.
Finally, there are ongoing studies testing whether fiber intake and certain probiotic compounds might enhance the effectiveness of chemotherapy and immunotherapy. (Source: Memorial Sloan Kettering News- 2025, Issue 1)
Resources for Living With Stage 4 Cancer
Learn more about topics like fiber and cancer prevention, along with other important aspects of living with Stage 4 cancer. Become a member of our community to receive inspiring stories, helpful resources, and updates on how we support individuals and families facing advanced-stage cancer. Stay informed with the latest research and gain early access to educational content.
Boosting Cancer Immunity Through Fasting
Fasting and Cancer Immunity Explained
How Fasting May Supercharge the Immune System to Better Fight Cancer…
More than a dozen types of cancer are sensitive to obesity, which can cause inflammation that damages cells, increased hormone levels, and other changes. So it makes sense for researchers to explore whether fasting to slow body fat and improve metabolic health might improve outcomes.
Now laboratory researchers at Memorial Sloan Kettering Cancer Center (MSK) and their collaborators have found that fasting can SUPERCHARGE the immune system’s “natural killer” cells. (Natural killer cells, or NK cells, for short, are a type of white blood cell that can kill abnormal or damaged cells, such as cancer cells.)
Fasting can reprogram the metabolism of natural killer cells, the team found in a study of mice. Those reprogrammed cells are better able to survive in the harsh environment in and around tumors. Their cancer-fighting ability is stronger, too.
The research, which was published in Immunity — one of the top immunology journals — explains how natural killer cells get reprogrammed during periods of fasting. The researchers are optimistic that what they’re learning in animal models could help make human immunotherapies more effective in people.
“Tumors are very hungry,” says immunologist Joseph Sun, PhD, the study’s senior author. “They use up the essential nutrients flowing to normal tissue. In that nutrient-starved environment, it is harder for natural killer cells to survive, so their function is impaired. Fasting reprograms these natural killer cells to better survive in this suppressive environment.”
What Are Natural Killer Cells?
Natural killer cells get their name because they can destroy a threat without having to recognize that threat — unlike other immune cells, called T cells, which require exposure to a specific threat in order to target it.
In general, the more NK cells that are present within a tumor, the better the prognosis is for the patient.
How Fasting Reprograms and Redistributes NK Cells
For the study, mice with cancer were fasted for 24 hours twice a week and then allowed to eat freely in between fasts. While the mice did not lose weight, the fasting had a profound effect on their natural killer immune cells.
Just as happens in humans, fasted mice saw a drop in their glucose levels and a rise in free fatty acids, which are lipids released by fat cells.
“During each of these fasting cycles, NK cells learned to use these fatty acids as an alternative fuel source to glucose,” says study first author Rebecca Delconte, PhD, a postdoctoral fellow in the Sun Lab. “This really improves their response against cancer and helps them survive in the harsh environment around the tumor.”
Fasting also led NK cells to travel to and interact with different parts of the body in big numbers. Many of the NK cells travel into the bone marrow, where they are programmed to develop a more powerful response against cancer. Meanwhile, NK cells that travel to the spleen undergo a separate reprogramming, making them better able to use lipids as a fuel source.
“With both of these mechanisms put together, we find that NK cells will move to the tumor and be primed to better kill the cancer cells,” Dr. Delconte says. “They’re more able to survive in this harsh environment, and their power is strengthened against cancer cells.”
Potential To Improve Cancer Treatments
There are several potential opportunities to advance the mouse-model research toward treating patients in the clinic, the researchers say.
First, clinical trials are already beginning to study the safety and effectiveness of fasting in combination with standard treatments. Another avenue would be to identify drugs that could mimic the underlying mechanisms without requiring patients to fast. Third, small molecules might be able to be put into a pill and taken outside of the body and then administered back to patients to improve treatment effects.
Right now, however, more clinical data is still needed about the effects of fasting for people with cancer, MSK researchers say.
There are many different types of fasting, and some might be helpful while others might be harmful. Patients should speak with their doctors about what’s safe and healthy for their individual situation. (Source: Memorial Sloan Kettering News- 2025, Issue 1)
Resources for Living With Stage 4 Cancer
Learn more about topics like fasting and cancer immunity, along with other important aspects of living with Stage 4 cancer. Become a member of our community to receive inspiring stories, helpful resources, and updates on how we support individuals and families facing advanced-stage cancer. Stay informed with the latest research and gain early access to educational content.
A New Cancer Therapy: Exercise
How Exercise and Cancer Treatment Outcomes
New Cancer patients may be surprised to learn they share something in common with astronauts in outer space.
It turns out that lying in bed and floating in zero gravity take a similar toll on the body, says Jessica Scott, PhD. She knows because she was a NASA scientist before joining the Exercise Oncology Program at Memorial Sloan Kettering Cancer Center (MSK).
“Astronauts have a lot of the same symptoms as cancer patients — being inactive and weightless can hurt fitness in a way similar to receiving a cancer treatment like chemotherapy,” Dr. Scott says. “Astronauts even get something called ‘space fog,’ which is similar to what people with cancer call ‘chemo brain.'”
When Dr. Scott saw how exercise can counteract the damage in space to the heart, brain, and muscles, she wanted to apply those lessons to benefit the millions of people with cancer.
Reducing the Toll of Cancer and Its Treatment
Contrary to popular belief, the best way for patients feeling depleted to recover is not necessarily to stay in bed.
“It’s now clear that exercise has major benefits for people being treated for cancer as well as for cancer survivors,” says MSK exercise physiologist Kylie Rowed. “In addition to improving physical and mental health, it can help minimize the long-term effects of cancer treatments such as chemotherapy and radiation.”
The benefits can be dramatic. For example, MSK research showed that people who endure three months of chemotherapy had a 15% decline in fitness levels within three to six months of treatment — equal to a decade of aging. But exercising just three times a week significantly reduced that steep decline.
Recently, the Exercise Oncology Program has taken the research a step further, conducting studies that shed light on whether exercise can affect cancer survival and recurrence and help new cancer drug therapies work better.
There is even tantalizing evidence that exercise might change the biology of the cancer itself, slowing its growth.
A First-of-Its-Kind Clinical Trial
In July 2024, Dr. Jones’s team published results in JAMA Oncology from a groundbreaking clinical trial suggesting that specific amounts of exercise before surgery among men with early-stage prostate cancer can meaningfully improve two key biomarkers associated with better outcomes.
“To our knowledge, this is the first clinical trial to research the optimal amount of exercise therapy for people with any kind of cancer diagnosis,” Dr. Jones says.
Previous research, including MSK’s, had shown that exercise was associated with a lower risk of prostate cancer progressing, and that men who report exercising regularly have a lower risk of dying from the cancer. But as all scientists know, correlation is not causation.
The true test is “treating” patients with controlled amounts of exercise therapy prescribed in the same way drugs are tested and prescribed — in specific “doses” administered over specific periods.
Researchers wanted to know: What is the most exercise people could reasonably be expected to do? Does the exercise have any biological effect on the tumor itself? And perhaps most important: How much exercise is enough?
To find out, the researchers studied 53 men scheduled to undergo surgery for prostate cancer at MSK. This allowed them to examine the tumor at two different points: when the tumor was biopsied at diagnosis and again at the time of surgery — usually about four weeks later. That provided a four-week window to test the effects of exercise alone, when none of the patients had undergone any treatments such as radiation or chemotherapy.
Participating in Research From Home
To make it as convenient as possible, the team found a way for most parts of the study to be done at home. They delivered a study kit that included a treadmill, an iPad loaded with apps, a smartwatch, a continuous glucose monitor, a blood pressure cuff, and a digital scale.
All exercise sessions consisted of walking on a treadmill while being monitored via Zoom by an exercise physiologist. Each participant was assigned one of the following “doses” of exercise:
- 90 minutes per week
- 150 minutes per week
- 225 minutes per week
- 300 minutes per week
- 375 minutes per week
- 450 minutes per week
The results were eye-opening. After exercise, the biomarkers either decreased or remained stable. Interestingly, there seemed to be a sweet spot: Most of the benefit was achieved with 225 minutes (3 hours and 45 minutes) of exercise a week. More than that amount had no greater impact on biomarkers.
“This was a key finding because it challenges the notion that ‘more is always better’ when it comes to exercise,” Dr. Scott says.
While encouraging, these results don’t prove exercise will improve someone’s cancer prognosis.
The researchers were looking only to see if exercise had an impact on the tumor, in the form of a biological signal over the short term. Determining if exercise leads to longer survival or better outcomes will require longer and larger clinical trials.
There is already a phase 2 clinical trial underway using the 225-minute dose level to better understand how exercise impacts prostate cancer progression. Similar trials are expected for other solid tumor cancers, including lung cancer, particularly those driven by specific mutations responding differently to exercise.
Establishing Exercise as Essential for Cancer Treatment and Prevention
“The hope is that people can be referred to an exercise physiologist who can give them a personalized prescription tailored to their physiology, tumor characteristics, and overall situation — much in the same way cancer drugs are personalized,” Dr. Scott says.
In the meantime, patients say exercising improves their overall well-being.
“I think the sense of control the exercise gave me was very important at a time when I was feeling somewhat helpless,” Robert says. “As a cancer patient, it was something 100% under my power that could help my recovery.” (Source: Memorial Sloan Kettering News- 2025, Issue 1)
Resources for Living With Stage 4 Cancer
Learn more about topics like exercise and cancer treatment, along with other important aspects of living with Stage 4 cancer. Become a member of our community to receive inspiring stories, helpful resources, and updates on how we support individuals and families facing advanced-stage cancer. Stay informed with the latest research and gain early access to educational content.
