A new study found linked to CT scans to increased cancer risk, but the overall risk remains low. Reza Estakhrian/Getty Images
A new study suggests that CT scans may slightly increase the lifetime risk of developing cancer.
The researchers say the cumulative effects of ionizing radiation over time should not be ignored.
Other experts say the risk of cancer from CT scans is minimal, and these imaging exams are an important diagnostic tool for various cancers.
A commonly used computerized scan may slightly increase cancer risk over a person’s lifetime.
That’s according to a new study published in JAMA Internal Medicine, an online publication of the American Medical Association.
Researchers from the United Kingdom and the United States report that computed tomography (CT) scans could drive an estimated 103,000 future cancer cases.
If true, that would mean CT scans would account for 5% of all new cancer diagnoses in the United States.
Researchers reported that the number of CT exams performed each year in the United States has increased by more than 30% since 2007.
They said the technology can save lives by detecting cancer early, but they expressed concern over the potential dangers of low doses of ionizing radiation over time.
“CT can save lives, but its potential harms are often overlooked,” said Rebecca Smith-Bindman, MD, a radiologist and professor of epidemiology and biostatistics as well as obstetrics, gynecology, and reproductive sciences at the University of California San Francisco (UCSF), in a press statement.
“Given the large volume of CT use in the United States, many cancers could occur in the future if current practices don’t change,” added Smith-Bindman, the study’s lead author.
CT scans help detect cancer early
In response to the new research, the American College of Radiology (ACR) stated that no published studies directly link CT scans to cancer.
They added that there are many benefits to diagnostic tests such as CT scans.
“Americans should not forgo necessary, life-saving medical imaging and continue to discuss the benefits and risks of these exams with their healthcare providers,” the ACR added.
Richard Reitherman, MD, a radiologist and medical director of breast imaging at MemorialCare Breast Center at Orange Coast Medical Center in California, agreed. Reitherman wasn’t involved in the study.
“CT scans aid in the diagnosis and treatment of conditions that may otherwise lead to increased morbidity and mortality if CT scans are not used,” Reitherman told Healthline.
“Since the harms that patients would otherwise experience by not using CT scans is not addressed, the clinical application of these results [of the study] is not actionable,” he added.
Patricia Nguyen, MD, an associate professor in the Division of Cardiovascular Medicine at Stanford University in California, stressed the benefits of CT scans. Nguyen wasn’t involved in the study.
“CT tests are important for evaluating patients who present with symptoms and signs of cancer,” she told Healthline. “When the benefits outweigh the risks of a test and the test is clinically indicated and will inform decision making (e.g., lead to a diagnosis that then leads to treatment), then a CT test should be performed.”
Calculating cancer risks from CT scans
In their study, the researchers used data collected from 143 hospitals and outpatient facilities between 2018 and 2020 and catalogued in the UCSF International Dose Registry.
From that, the researchers estimated there were 93 million CT scans performed on nearly 62 million people in the United States in 2023.
The researchers said that based on associated radiation risks, they estimate that CT scans in 2023 could be linked to 103,000 future cancer diagnoses.
They reported that radiation-induced cancers would be at a higher rate in children and adolescents than in adults.
They also estimated that the most common cancers among adults would be lung cancer, followed by colon cancer, leukemia, and bladder cancer. In females, breast cancer was the second most common, while in children, the most frequently projected cancers were thyroid, lung, and breast.
The highest number of cancers in adults was projected to come from CT scans of the abdomen and pelvis, followed by chest scans. In children, cancers were linked to CT scans of the head.
The researchers acknowledged that the cancer risk from CT scans remains minimal and needs to be examined over decades of large-scale follow-up studies.
However, they said some changes should be considered in how often these diagnostic tests are used.
“Our estimates put CT on par with other significant risk factors, such as alcohol consumption and excess body weight,” Smith-Bindman said. “Reducing the number of scans and reducing doses per scan would save lives.”
“Current practice includes measures of radiation dosage for each exam,” he said. “This process is reducing the number of examinations and dosages. This is an ongoing process that will reduce the theoretical impact of radiation-induced cancer.”
What to know about CT scans
CT scans combine a series of X-rays into 3-dimensional pictures.
These medical imaging tests use ionizing radiation to create cross-sectional images of selected areas of the body.
These pictures can show internal organs, bones, blood vessels, and soft tissues.
CT scans are used to detect tumors, blood clots, internal bleeding, and infections.
These scans usually require more exposure to radiation than common X-rays. However, they also provide medical professionals with a more detailed look inside a person’s body.
CT scans, for example, are considered the most beneficial exam for early detection in lung cancer.
“Lung cancer screening constitutes the largest proportion of screening examinations,” Reitherman explained.
“Lung cancer screening is performed on patients that have a significant risk for developing lung cancer due to chronic smoking histories. Screening CT scans in this group of patients has been shown to decrease the stage at diagnosis and therefore improve outcomes. Benefit far outweighs the risk.”
CT scans are also considered the “gold standard” for detecting pulmonary embolisms, blood clots that block blood flow within the lungs. They are also useful tools in getting accurate images of the brain.
Nguyen said that people should “always limit their exposure to radiation.” In addition, they should ask questions of their doctors, such as:
What is the total radiation of this test?
Is a dose report available?
Is there an alternative test that doesn’t produce radiation?
Reitherman also urged people to be involved in their medical decision making.
“Patients should be advocates for themselves in discussing every form of diagnostic testing with their physicians. This would include CT scans as well as lab tests, etc.,” he said. “Conversations about risk and benefits are important so that individuals can optimize benefits and reduce potential risks.”
Many plant-based proteins are less digestible and may have lower concentrations of one or more essential amino acids. Kseniya Ovchinnikova/Getty Images
Vegans who meet their daily protein requirements may still fall short on certain essential amino acids, according to new research.
The study highlights that protein quality, not just quantity, plays a critical role in meeting nutritional needs.
Unlike animal-based proteins, many plant-based proteins are less digestible and may have lower concentrations of one or more essential amino acids.
Vegans who consume adequate protein may still not get enough of certain essential amino acids in their diet, according to new research.
While prior studies have tended to focus on the total amount of protein consumed in a vegan diet, a new study, published on April 16 in PLOS ONE, has honed in on specific amino acids. When considering digestibility, the research found that only about half of the participants appeared to meet the body’s requirements for lysine and leucine.
The study emphasizes the importance of evaluating not just total protein consumption, but also protein quality and amino acid composition in a vegan diet.
Amino acids are the “building blocks” of protein. While the body can produce some amino acids on its own, nine essential amino acids must come from dietary sources.
Plant-based proteins were previously viewed as “incomplete proteins,” lacking certain essential amino acids. We now understand that they provide all nine essential amino acids, but sometimes in less optimal levels than in animal-based foods.
This means those following a vegan diet must consume a strategic variety and quantity of foods, such as nuts and legumes, to get enough of the essential amino acids.
“Consuming 30 grams of lower quality plant protein, such as wheat, is different from consuming the same quantity of protein from soy, a higher quality plant protein,” said Bi Xue Patricia Soh, MSc, first author of the study and a PhD fellow with The Sustainable Nutrition Initiative Team at the Riddet Institute, Massey University, New Zealand.
“Our findings therefore support that, even when we are meeting total protein requirement, the foods consumed may not be of adequate protein quality in terms of supplying sufficient lysine and leucine required for body functions,” Soh told Healthline.
50% didn’t meet amino acid requirements
Soh and her team conducted a cross-sectional study of 193 long-term vegans in New Zealand (141 women, 52 men).
Participants were healthy adults who had followed a vegan diet for at least two years. Each completed a detailed four-day food diary documenting all food, beverages, and supplements consumed over consecutive days.
The team strengthened their analysis by adjusting for protein digestibility, which measures how efficiently the body breaks down and absorbs protein and amino acids from different food sources.
After adjusting for digestibility, the researchers found that while most participants met their overall protein requirements — 78.8% of males and 73.0% of females — many fell short on lysine and leucine intake.
Soy protein, for example, has one of the highest digestibility ratings among plant foods, allowing the body to utilize nearly all of its nutrient content. In contrast, wheat protein has lower digestibility rates due to the presence of antinutrients and other factors.
This distinction is crucial because many assessments of plant-based diets may overestimate actual protein availability by not accounting for digestibility — a finding clearly borne out in the study.
After adjusting for digestibility, about 25% of participants did not meet their protein requirements. The shortfall was even more pronounced for specific amino acids: only 43.5% of participants met their requirements for digestible leucine, and just 56% consumed adequate digestible lysine.
The remaining essential amino acids were generally present in sufficient amounts even after the digestibility adjustment.
What are the 9 essential amino acids?
The nine essential amino acids are as follows:
phenylalanine
valine
threonine
tryptophan
methionine
leucine
isoleucine
lysine
histidine
Since the body cannot synthesize essential amino acids on its own, eating a well-balanced diet is crucial, especially for those following a vegan diet.
“Essential amino acids play an important role in general health. Therefore, ongoing deficiency has the potential to create adverse health effects,” Kristin Kirkpatrick, MS, RD, a nutritionist at the Cleveland Clinic, and co-author of “Regenerative Health,” told Healthline.
These nine essential amino acids play an important role in many essential functions of the body, including:
stimulating muscle growth
fat metabolism
immune function
sleep regulation
appetite control
regulating blood sugar
calcium absorption
“Lysine and leucine contribute to normal bone health, healthy muscle mass, and DNA methylation. Leucine in particular has important roles in cell signaling pathways that modulate muscle protein synthesis,” said Soh.
Keys to eating a nutritious vegan diet
“The easiest and most feasible way is to ensure diverse plant proteins are consumed in the three meals of the day and supplement this with one or two protein-dense snacks — nuts, seeds, [and] protein shakes with isolates that have higher amino acid digestibility,” said Soh.
The study found that legumes and pulses, such as edamame, black beans, chickpeas, and lentils, were the top sources of digestible protein and lysine.
“Even when hitting adequate protein amounts, we want a well-balanced diet rich in fiber and other nutrients,” Alyssa Kwan, MS, RD, a clinical dietitian in cardiology at Stanford Medicine, not involved in the study, told Healthline.
Unlike animal-derived proteins, which contain all nine essential amino acids in adequate amounts, plant proteins often need to be combined to reach the same nutritional benchmark.
But you don’t need to combine specific foods at every meal. Consuming various plant-based proteins throughout the day and emphasizing high quality plant-protein sources like beans and soy products can help you meet your needs for essential amino acids.
Still, Kwan noted that a diet must be examined holistically rather than focusing on individual parts.
“I do not think we need to target adequate lysine or leucine or even any other specific amino acids. I would say focusing on high fiber and protein plant-based foods should help achieve any discrepancies in essential amino acids,” she said.
Kirkpatrick added that following a vegan diet doesn’t automatically guarantee balanced nutrition. Intentional food choices are key.
“Some of the vegan patients I have worked with in the past have started on their own and made choices that did not always speak to good nutrition. This could have been choosing ultra-processed vegan foods, not focusing on nutrient density, and a lack of knowledge of when supplementation may be necessary,” she said.
New research suggests an early intervention with two common, low cost drugs could be lifesaving after a heart attack. PixelCatchers/Getty Images
A new study found that adding a second drug early after a heart attack may save lives.
Those who added ezetimibe to a statin had fewer complications and deaths.
The authors say that early combination therapy should become the standard of care.
Experts say addressing underlying inflammation can also help control cholesterol.
New research from Sweden suggests that starting a second cholesterol-lowering drug soon after a heart attack may help save lives.
According to the study, published in the April 2025 issue of the Journal of the American College of Cardiology, people who received ezetimibe (brand name Zetia) with their statin therapy within 12 weeks of a heart attack had fewer heart-related complications and deaths than those who waited longer or never added ezetimibe at all.
The National Library of Medicine explains that ezetimibe helps reduce the amount of low-density lipoprotein (LDL) cholesterol in your blood by preventing cholesterol from being absorbed in the small intestine.
LDL cholesterol is the so-called “bad” cholesterol associated with clogged arteries and an increased risk of cardiovascular diseases such as heart attack and stroke.
Ezetimibe is sometimes prescribed for people who can’t tolerate statins. It may also be used as an add-on treatment when statins do not sufficiently lower cholesterol.
This medication works differently from statins, which exert their cholesterol-lowering effects by slowing down the liver’s production of the waxy substance.
Early combination therapy after heart attack may save lives
To arrive at their conclusion, the researchers analyzed data from more than 35,000 patients hospitalized for heart attacks (myocardial infarction) between 2015 and 2022, using the comprehensive SWEDEHEART registry in Sweden.
Most patients were prescribed high-intensity statins at discharge, but a subset also began taking a second medication, ezetimibe, within the first 12 weeks after discharge.
The study categorized patients into three groups: those who started ezetimibe early (within 12 weeks), those who started late (13 weeks to 16 months after discharge), and those who never received ezetimibe during this period.
Importantly, the analysis used advanced statistical methods — specifically, a clone-censor-weight framework — to emulate a randomized clinical trial and minimize biases
Results showed that patients who started ezetimibe early in combination with statins had a significantly lower risk of major adverse cardiovascular events (MACE), which include death, another heart attack, or stroke, compared to those who delayed ezetimibe or never took it.
One-year incidence rates of MACE were 1.79 per 100 patient-years in the early ezetimibe group, compared with 2.58 in the late group and 4.03 in those without ezetimibe.
At three years, the hazard ratio for MACE was 1.14 for late versus early treatment (not statistically significant) but was 1.29 for no ezetimibe versus early treatment, indicating substantially higher risk without ezetimibe.
Cardiovascular death was also significantly higher in the late and no ezetimibe groups compared to early treatment.
Additionally, early combination therapy led to a greater proportion of patients achieving guideline-recommended LDL cholesterol targets (<1.4 mmol/L or <55 mg/dL) within one year.
What are the implications for heart attack patients?
The study underscores that a stepwise approach — starting with statins and adding ezetimibe only if LDL cholesterol goals are not met — inevitably delays optimal cholesterol lowering and is associated with avoidable harm.
As the authors note, approximately 75–80% of post-heart attack patients fail to reach LDL goals with statin therapy alone; initiating combination therapy early can improve outcomes and reduce future cardiovascular events.
To maximize protection, the researchers advocate that care pathways for heart attack patients should be updated to implement early combination therapy with statins and ezetimibe as standard care, potentially even before hospital discharge.
Arun Manmadhan, MD, assistant professor of cardiology at Columbia University Irving Medical Center, who was not involved with the study, said the findings align with a broader body of research showing that sustained, low LDL cholesterol levels are associated with fewer heart attacks and strokes.
“This is even more important in people who have already experienced one of these events,” he said, “because lowering the cholesterol levels, in addition to optimizing other cardiac risk factors, is one of the most effective and proven ways to prevent a second event.”
Manmadhan said that, in his opinion, this study adds to the evidence that patients who have had a heart attack or stroke should have their cholesterol levels aggressively managed, both through lifestyle and medications.
“This study suggests that time is also an important factor,” he added. “[The] earlier and faster cholesterol levels are aggressively controlled to recommended levels after a heart attack, the better it is for preventing future cardiovascular events.”
What can patients do beyond cholesterol-lowering drugs?
Markyia Nichols, MD, MPH, RDN, a CDC-certified lifestyle coach and chief medical officer at Ciba Health, said patients should know that “cholesterol isn’t the enemy.”
“It’s a response,” she explained. “Cholesterol is essential for life. It builds hormones, stabilizes cells, and repairs tissue. If cholesterol is rising, it’s critical to ask what the body is trying to repair or protect against.”
According to Nichols, inflammation is the real problem, not cholesterol. A diet high in sugar, processed seed oils, and ultra-processed foods, insulin resistance, metabolic dysfunction, chronic stress, and exposure to toxins can all factor into creating inflammation.
“Once the heart lining is damaged, the body sends cholesterol as a patch,” she said. “Cholesterol doesn’t cause the ‘fire.’ It acts more like the ‘firefighters.’”
Nichols added that, digging deeper, LDL only becomes dangerous when it’s oxidized due to poor nutrition.
Circling back to the study, she told Healthline that while adding ezetimibe to statins post-early heart attack may lower cholesterol, it’s not addressing the root causes of the problem. Patients also need to focus on nutrition.
“Ask for labwork that tests levels of magnesium, omega-3s, vitamin D, and vitamin K2,” she advised. “You can’t rebuild a healthy heart without healthy raw materials.”
She also suggests looking to see whether your markers of inflammation, such as C-reactive protein, homocysteine, and insulin, are high.
Further, look for any sources of inflammation you might have, like a poor diet, stress, toxins, or an unhealthy gut.
Nichols concluded by saying that you may need to see a board-certified doctor trained in root-cause medicine to determine what’s causing your inflammation.
However, addressing this can help you heal the underlying causes of your high cholesterol.
Health agencies and experts recommend fluoride in drinking water at low levels (currently 0.7 mg/L in the U.S.) to promote dental health. LukaTDB/Getty Images
HHS Secretary Robert F. Kennedy Jr. called for a ban on fluoridated water in U.S. communities.
Emerging evidence shows potential health harms and neurotoxic effects in young children, but experts caution these studies are limited and the findings should be interpreted with caution.
Experts have called for more robust studies on the potential health effects of fluoridated water in Americans.
Health agencies recommend fluoride in drinking water at low levels (currently 0.7 mg/L in the United States) to promote dental health.
The debate over the safety of fluoride in drinking water was reignited earlier this month when Health and Human Services Secretary Robert F. Kennedy Jr. proposed a ban on fluoridated water in communities across the United States.
In tandem with the health secretary’s announcement, the Environmental Protection Agency (EPA) announced at a press conference in Salt Lake City on April 7 that it would review “new scientific information” about the purported health risks of fluoridated water.
The EPA is responsible for setting the maximum levels of fluoride allowed in public drinking water, which is currently 0.7 milligrams per liter (mg/L), according to the Centers for Disease Control and Prevention (CDC).
Kennedy’s move coincides with a recent ban in Utah, the first state to prohibit fluoride in drinking water.
Kennedy told The Associated Press that he plans to assemble a task force to investigate the issue and draft new recommendations on fluoridated water.
While Kennedy cannot outright ban fluoridation across U.S. communities, he could order the CDC to change its recommendation. He can also work with the EPA to change the maximum threshold of fluoride in drinking water.
Fluoride, a naturally occurring mineral, was first added to water in U.S. communities in the mid-1940s to protect dental health, particularly in areas with limited access to dental care.
These health agencies attest that the current designated levels of fluoride in drinking water are safe and that fluoride toothpaste and supplements are safe for use in age-appropriate amounts.
“When government officials, like Secretary Kennedy, stand behind the commentary of misinformation and distrust peer-reviewed research, it is injurious to public health,” Brett Kessler, DDS, president of the American Dental Association, said in a statement.
“Let’s stop the rhetoric and comprehensively study fluoride at the optimal level once and for all,” he said.
Research on the effects of fluoride exposure is limited and ongoing. The problem with the current literature is a lack of substantial evidence supporting the potential health harms to populations within the United States, most notably the possible neurotoxic effects in children.
Adding to the confusion, fluoride levels are much higher in many countries outside the United States, where research on fluoride exposure is more common. What’s more, most European countries and some provinces in Canada do not add fluoride to drinking water at all.
Despite advancements in dental care and the unknowns about potential health effects, many people may wonder why fluoride is still in our drinking water.
“What’s happened over the past, say, two decades is that there has been growing evidence that fluoride exposure in children, and in particular, in the developing child, is neurotoxic,” said Bruce Lanphear, MD, MPH, professor of health sciences at Simon Fraser University in British Columbia, Canada.
“That is, it’s associated with diminished IQ scores, which is very much along the lines of what we’ve seen with lead in children. Should we expect universal agreement? Absolutely not. We don’t see a universal agreement with lead. We see more agreement with lead, but we have a much more stable measure of lead,” Lanphear told Healthline.
What are the health risks of fluoride exposure?
In 2015, the amount of fluoride added to water to prevent tooth decay was lowered from 1.2 mg/L to 0.7 mg/L due to increased fluorosis in children in recent decades.
Rates of dental fluorosis, a common condition that causes tooth discoloration and brown and white spots on permanent teeth, have nearly doubled among adolescents in the United States.
“It seems to have plateaued,” Lanphear said of the condition, “but it has increased quite a bit, and the only reason is [children are] getting too much fluoride.”
Health Secretary Kennedy’s position on fluoride may be partially influenced by a recent global study published in January in JAMA Pediatrics. The study suggests that children exposed to higher fluoride levels in water had lower IQs, igniting controversy among health experts on both sides of the ongoing discussions over its safety.
Fluoride proponents note these findings are based on exposure in children in non-U.S. countries, mainly in China and India, where fluoride levels are much higher. The American Dental Association urged the public to interpret the findings with caution.
“I think there’s been a lot of fear that’s been instilled by RFK Jr. and his associates,” said Danelle Fisher, MD, FAAP, board certified pediatrician at Providence Saint John’s Health Center in Santa Monica, CA.
“We need to start by ensuring people that currently they are safe and that we have effective ways to keep their kids healthy and safe. In the case of dental health, it’s correctly fluoridated water — and we do see good dental health with the kids who are exposed to our water and fluoridated toothpaste,” she told Healthline.
The JAMA Pediatrics study followed the release of a massive report from the National Toxicology Program published in August 2024 by the National Institutes of Health. Similarly, the report linked high levels of fluoride exposure in children to a small decrease in IQ, prompting opponents to reevaluate current fluoride levels in U.S. water systems.
However, the report notes flaws in its study, citing insufficient data to determine whether the current low fluoride level of 0.7 mg/L in U.S. community water systems negatively affected children’s IQ.
“We have growing evidence that fluoride is neurotoxic because kids are getting too much fluoride, as evidenced by increasing rates of fluorosis, and because there’s now new evidence that fluoride is not effective when added to water at preventing tooth decay,” Lanphear said.
Lanphear, who co-wrote an accompanying editorial to the JAMA Pediatrics study, cited a 1995 animal study that found fluoride was associated with behavioral deficits in rats.
“Many of the early studies were cross-sectional and not particularly high quality. And that’s been one of the major criticisms of this new evidence — but it really shouldn’t be a criticism, because that’s how most science evolves,” Lanphear said.
Indeed, many studies examining fluoride toxicity have been small in scale and were conducted in animals and in vitro.
Still, researchers have sounded alarm over the potential threats of fluoride exposure to human health. Many have cited dental fluorosis as a complication, while others have observed more serious effects.
A 2022 review of the literature suggests exposure to fluoride at levels much higher than the current 0.7 mg/L level in the United States or the maximum threshold of 1.5 mg/L set by the WHO could lead to a range of issues, such as:
skeletal fluorosis
arthritis
bone damage
osteoporosis
muscular damage
fatigue
joint-related problems
chronic health issues
damage to vital organs
endocrine or thyroid disruption
Still, as with other fluoride studies, these findings are limited and may be easily misinterpreted. For instance, the fluoride levels studied in the 2022 review exceeded the U.S. and global thresholds for fluoride in water. And of course, animal studies do not necessarily translate to humans.
Due to the limited nature of fluoride research, health experts and scientists remain divided on whether fluoride should remain in public drinking water or be removed entirely.
Inderpal S. Randhawa, MD, board certified internist, immunologist, pediatrician, pediatric pulmonologist, and medical director of the Children’s Pulmonary Institute at MemorialCare Miller Children’s & Women’s Hospital Long Beach in Long Beach, CA, noted the risk of tooth decay and poor dental hygiene still exists in some parts of the United States.
He told Healthline that Kennedy’s proposed ban on fluoridated water seemed reasonable in communities with widespread access to dental care and fluoride-based toothpaste. In areas with poor dental health, however, fluoride levels should remain as low as possible, he said.
“The concerns are real,” Randhawa said. “Long-term, systemic fluoride exposures can result in an excess amount of fluoride in the body. This can impact the bones, thyroid, and other organ systems. Reducing this risk in today’s advanced dental care is something to consider.”
Fisher said the current fluoride levels are safe but called for more studies with U.S. children to better understand the potential risks.
“It’s always important to look at whatever research is coming out and base our recommendations on what we think is in the best interest of the children who need this fluoride for good dental health — but obviously, we never want to do harm,” Fisher said.
“So, if there is compelling evidence that comes out that the fluoride supply in the water in the U.S., for instance, is too high and is leading to a decrease in IQ, which could potentially lead to cognitive decline, that is important information to know. The problem with making conclusions from the [JAMA Pediatrics] study is that it might be misguided.”
Fisher noted that the JAMA Pediatrics findings are based on countries with almost double the amount of fluoride in their water supplies.
“There’s nothing in there that studied children in the U.S., but since this is being cited as evidence, it is important not to create hysteria amongst families. If we’re going to do research that’s going to directly correlate IQ scores and fluoride exposure in the U.S., let’s do that study,” she said.
“Over time, we recognized there is an importance to having fluoride in our water supply. Adding fluoride to the water in an adequate amount was important to improve dental health. That is something that has absolutely been shown and demonstrated, especially here in the U.S.,” Fisher noted.
Fluoride exposure in adequate amounts appears safe
Many health experts agree that intermittent fluoride use appears safe and effective.
“As opposed to drinking fluoride in water where the exposure is systemic, local application with toothpaste-like products is much lower exposure,” Randhawa said. “Similarly, receiving such treatments at the dentist is minimal exposure.”
Fisher said that before fluoride was introduced to drinking water, dental and other health problems were significant in areas with scarce access to fluoride and proper dental care.
“When we didn’t have fluoride in the water, we saw so much more teeth problems and subsequent problems that came from that,” she said.
“The amount of dental decay and disease was rampant, and it is rampant in parts of the world where kids don’t have access to fluoride. Dental problems don’t just affect the teeth, they affect the entire child. We are talking about kids who would go on to potentially develop brain problems, brain abscesses that spread from dental decay,” Fisher explained.
Lanphear shared a different perspective, noting the risks of water fluoridation may outweigh the potential benefits.
“The evidence about the effectiveness of water fluoridation or systemic fluoride has never been rigorous,” he said, citing a large systematic review published in 2024 in Cochrane Review.
Researchers examined evidence dating back to 1975 on whether water fluoridation is effective in reducing tooth decay. They found that fluoridated water had little to no benefit in preventing cavities, maybe a 3% to 4% reduction, Lanphear noted, which meant it was not statistically significant. This, he said, questions the benefit side of the equation.
Lanphear also cautioned against fluoride-based toothpaste for young children, which contradicts current pediatric recommendations. “Children 1 to 4 years old might be getting 80% of their fluoride from swallowing toothpaste,” he surmised.
Be that as it may, fluoridated water remains at very low levels in U.S. communities for now, and pediatric dentists continue to recommend fluoride-based toothpaste.
Pediatricians like Fisher recommend that children under 6 years old use a pea-sized amount of fluoridated toothpaste twice daily. Fisher said pediatricians and dentists consider this a safe amount to ingest if swallowed since most young children do not know how to spit.
“Are we swallowing too much toothpaste? There’s no evidence to show that we are. However, if studies are done in the future that do demonstrate that, we will adjust our recommendation, but currently, there’s no need to panic,” she said.
More studies on fluoride exposure needed
Fisher reiterated that the fluoride levels in U.S. water systems are adequate but urged further study of the potential effects.
“Let’s look at how we as a society, as Americans, can best supply a good amount of fluoride to our kids so their teeth and brains are healthy,” she said.
“It would be great to see a prospective study of American children, meaning you look at them first and then follow them over time and watch their developments, and you can measure IQ, if you want,” she said.
Fisher noted there are other ways to assess cognitive development that don’t involve IQ scores.
“I think those studies will be interesting and important, and potentially, if we find out that the amount of fluoride in our water is too much or not enough, we can adjust it accordingly,” she said.
Lanphear agreed that more research on fluoride, in general, is needed, but opposed fluoridated water.
“I think, at a minimum, what we can say is it’s time to convene an independent scientific panel to review the evidence on the safety and purported benefits of water fluoridation,” he said.
“Fluoride toothpaste is efficacious, based upon good, rigorous, randomized, controlled trials. Drinking it or taking it as a supplement does not appear to be efficacious. So given all of that, if you ask me, and I had to make that decision as an individual, I’d say, absolutely take it out of the water,” Lanphear said.
Fisher, on the other hand, remained optimistic about the low levels of fluoride in water and offered reassurance about current best practices for dental health.
And if there is one thing most, if not all, experts agree on, it’s that more research on the effects of fluoride exposure is needed.
“Scientists are here to make sure that we have good health, for ourselves, for our children. Nothing is more important,” Fisher said. “We do need fluoride. We need a good amount, and we should not panic about this.”
Moderate daily exercise significantly reduced the risk of death from cardiovascular disease among female cancer survivors, a new study found SolStock/Getty Images
Among older female cancer survivors, moderate daily exercise significantly reduced the risk of death from cardiovascular disease.
Cancer survivors are statistically more likely to develop cardiovascular disease.
Reducing sedentary time and increasing activity can be easily integrated into daily life to lower cardiovascular disease risk.
Staying active and limiting sedentary time is essential to reducing the risk of cardiovascular disease (CVD), but little research exists to show its effects in older female cancer survivors.
Now, researchers have found compelling evidence that getting more daily physical activity has a robust protective effect on heart health for this group.
Moderate daily exercise — through exercise sessions or hitting daily step goals from walking — significantly reduced the risk of death from cardiovascular disease in postmenopausal cancer survivors.
In another promising development from the study, researchers found that exercising at levels below current recommendations showed significant benefits, underscoring that every little bit counts when it comes to exercise.
The findings are essential for the long-term health of cancer survivors, who are at increased risk of CVD compared to other adults.
“While health benefits were maximized at 60 min [per] day of moderate-to-vigorous physical activity and around 5,000–6,000 steps/day, there were substantial health benefits evident at amounts below these levels,” Eric Hyde, PhD, MPH, a research analyst at the University of California, San Diego, and presenter of the research, told Healthline. “Encouraging cancer survivors to sit less and take more steps may help promote long-term survival.”
Moderate exercise reduced death risk from CVD by 60%
Hyde and his team utilized accelerometer data from nearly 2,500 female cancer survivors to see how daily exercise affected all-cause and CVD-related mortality risk.
That data resulted from two studies conducted between 2011 and 2015 and an additional four years of follow-up, collectively known as the Women’s Health Accelerometry Collaboration.
The females involved in those studies were between the ages of 63 and 99, with an average age of 74. They wore a fitness tracker for at least 10 hours per day for up to one week. The device recorded bouts of exercise, step count, and sedentary behavior.
The cohort experienced different forms of cancer, the most prominent of which were breast (52%), endometrial (8.5%), and malignant melanoma (7.1%). Other cancers included:
lung
bladder
ovarian
rectal
bladder
colon
myeloma
kidney
head and neck
When Hyde examined the association between physical activity data from the exercise trackers and mortality, those who exercised or walked more had significantly better health outcomes. Engaging in one hour per day of moderate to vigorous physical activity lowered the risk of death by 40% and the risk of death linked to CVD by 60%.
CDC guidelines and the AHA recommend that adults get at least 150 minutes of moderate-intensity physical activity weekly.
If you count your physical activity in steps rather than time spent exercising, the greatest benefit was seen in participants who clocked 5,000-6,000 steps per day, lowering the risk of death by 40%.
Note this is well below the more commonly touted 10,000 steps per day, a myth that’s been somewhat debunked since the optimal number may depend on your age.
However, the study did find additional benefits of more walking: each additional 2,500 steps per day was associated with a 34% further reduction in the risk of death from CVD.
On the other hand, sedentary behavior was linked to worse health outcomes. For every 102 minutes of sitting per day, participants’ risk of death from all causes increased by 12%, while the risk of CVD-related death jumped by 30%.
“In the past, clinicians used to advise cancer patients to rest and avoid activity when possible,” Hyde said.
“However, the evidence is now clear that those with a history of cancer can greatly benefit from being more physically active. There needs to be increased awareness of the importance of moving more and sitting less among cancer survivors.”
Exercising more, sitting less at any age
Keith Diaz, PhD, an associate professor of behavioral medicine at Columbia University Medical Center and member of the AHA’s Physical Activity Science Committee, not involved in the study, told Healthline that prioritizing health and time management is essential for hitting your daily activity goals.
“We work, we care for kids, we upkeep our living spaces. Yet some find the time for exercise and others don’t, said Diaz. “Instead of thinking of exercise as a structured activity that requires a dedicated time slot, it can help to integrate movement into the daily rhythms of your life.”
Diaz recommended various strategies that can help integrate more activity and less sitting into your daily routine. They include:
“Walk and talk.” Any time you’re on the phone, get some steps in rather than sitting down.
Link exercise to existing habits like meals or entertainment. When you finish your lunch or your favorite Netflix show, take a 5-minute walk afterward.
Try to squeeze in some movement whenever you can rather than fixating on a single exercise.
Eleanor Levin, MD, a clinical professor of cardiovascular medicine at Stanford Medicine, recommended exercising with a social group, such as a walking club, to stay motivated. Levin wasn’t involved in the new research.
Fatigue is a common problem for cancer survivors, so while exercise may seem even more strenuous to begin with, it will help to relieve this common symptom in the long run.
“Paradoxically, regular physical activity is one of the most effective ways to increase energy levels. Even small amounts of exercise can create a positive feedback loop — where exercise improves conditioning, reduces fatigue, and makes future physical activity feel easier,” said Diaz.
Takeaway
Among postmenopausal female cancer survivors, one hour of moderate exercise or 5,000 steps per day significantly reduced the risk of death from all causes and cardiovascular disease, new research shows.
On the other hand, every 102 minutes spent sitting per day was associated with a 30% increased risk of death from cardiovascular disease.
When it comes to exercise, every bit counts. Benefits have been identified even when exercising less than current guideline recommendations.
