• Ultra-processed foods are often marketed with misleading claims to seem healthier, a researcher says.
• Labels like 'low fat' and 'low calorie' can be a red flag that foods are full of additives.
• Being skeptical of health claims can help you get the most of out grocery shopping for a nutritious diet.

Grocery shopping can be a minefield of faux health foods that are biting into your budget and damaging your long-term health.

That's why, when Dr. Tim Spector is walking down the food aisle, he keeps his eyes peeled for red flags — things that sound healthy, but are quite the opposite.

Spector, a medical doctor and professor of epidemiology at King's College London, co-founded the science and nutrition company ZOE, which gives members nutrition advice, among other features.

He took a particular interest in nutrition research after he had a mini-stroke in 2011. He was just 53, and felt pretty healthy, but he began to take a closer look at his eating habits.

"I said, 'I need to change what I'm doing and do massive research to work out what I should be eating, what I should be doing, health-wise to keep me living longer,'" Spector, co-founder of the science and nutrition company ZOE, told Business Insider.

Now, he has made it his mission to help consumers spot "health halos" — misleading advertising on ultra-processed foods making them seem nutritious when they can be detrimental to your health.

Here are four red flags he looks for that can help you spot dubious claims at the grocery store, and how to stock your kitchen with healthier options instead.

1. 'Low-fat' foods have extra additives

Spector said he steers clear of anything labeled "low-fat," which includes margarine and butter substitutes, yogurts, and other dairy.

Low-fat products have a long history in the fad diet industry. The craze really took off in the 1980s because of concerns that saturated fat could worsen heart health and cholesterol levels. Companies selling low-fat substitutes for popular foods also cashed in on the myth that eating more dietary fat causes you to gain more body fat.

The problem is, trimming the fat from a food has a major catch. Since fat brings flavor and texture to food, swapping it out means adding sugars, starches, and binding agent so the final product is still appetizing.

That's good news for manufacturers, who saved money by using lower-cost additives, but bad news for consumers, who are now missing out on some heart-healthy fats that naturally occur in foods, and eating more preservatives instead.

The extra refined carbohydrates that are added in place of fats can wreck havoc on our health, raising the risk of heart disease and messing with metabolic health.

"Big food loved it because it was cheaper to have these sort of fat replacements than actually paying for the natural fat got in our diets," Spector said.

If you're trying to watch your cholesterol levels, Spector said skip the low-fat products. Instead, he avoids cooking oils and spreads, and uses extra virgin olive oil, which offers a dose of beneficial fatty acids and polyphenols.

He also buys full-fat butter, since emerging research suggests that the fat in dairy products can have a protective effect, potentially reducing risk of illness and promoting healthy aging.

2. 'Low-calorie' can be misleading

Labeling products as low in calories is a marketing ploy which often signals a food is ultra-processed and loaded with additives, Spector said.

"It means they've tampered with it. They have probably taken out some sugar and added artificial sweeteners to disguise how much sugar is in there," Spector said.

Many low- or no-calorie artificial sweeteners are no better for your health than sugar, according to a 2022 study.

For example, consuming aspartame, the no-calorie sweetener used in many diet sodas, carries some of the same health risks as excess sugar, like higher risk of heart disease, diabetes, and obesity. It may also cause you to eat more as the sweet taste prompts your body to expect a boost of energy that never arrives.

Spector has another gripe with the low-calorie label: calories alone aren't a good indication of whether a food is nutritious, he said. It's more important to focus on the nutrients in your food than one siloed metric. Plus, research suggests calorie labels can be off by as much as 20%.

"Calories are completely the wrong way to summarize a food. They're not accurate. They're not useful, as most people cannot follow a calorie-restricted diet or calorie count reliably," Spector said.

3. 'Added vitamins' tend to be low-quality nutrition

It's pretty common for food packages to declare "added vitamins" or "added minerals" — from cereals to juice to milk.

However, while getting an extra boost of vitamins and minerals in your food may seem like a bonus, it's another sneaky way to disguise processing, Spector said.

Ultra-processed foods are designed to have a long shelf life, with a hyper-palatable flavor and texture, tempting you to keep eating. That manufacturing process strips out naturally-occurring nutrients like vitamins and minerals. By law, manufacturers have to add them back in, Spector explained.

That's why Spector is not so impressed by foods advertised as "fortified" with vitamins and minerals.

Vitamins and minerals are most effective in the form of whole foods, since they're in larger quantities and in higher-quality form, easier for the body to absorb and use than the manufactured, isolated version.

4. Be wary of claims like 'immune-boosting' or 'gut healthy'

Food manufacturers will often hype up the appeal of their products by adding very small amounts of ingredients with promising nutritional benefits, even if the doses aren't large enough to do much good. In the supplement world, this is called "fairy dusting."

"You can claim immune health by adding a microscopic amount of zinc into it; gut health with a bit of manganese… all sorts of nonsense," Spector said

Misleading health claims also includes labels that advertise added fiber, since you may not be getting an effective dose.

"Big food doesn't make money out of fiber. There's no big fiber lobby. It's just quiet cheap, and it's healthy. And of course, it fills you up. So you eat less of it," Spector said.

The easiest way to navigate food labels is to check the actual quantities of ingredients and serving sizes, to make sure you're getting what you want, Spector said. Not all processed foods are created equal, since certain types of processing can retain the nutrients you want.

Spector's approach to getting enough nutrients is to aim to eat 30 different plants per week, including things like nuts, seeds, spices, coffee, and even high-quality chocolate.

• Increasingly, young people with clean diets and healthy lifestyles are getting colon cancer.
• Doctors say diet plays a role in the rising risk, but doesn't tell the whole story.
• We are learning more about ways microplastics, sleep cycles, and our environment may play a role.

At 30, Chris Lopez was hitting his stride. He was attending culinary arts school in Dallas. He was meal prepping and hitting the gym regularly, focused on getting a degree and setting up his life right.

His symptoms were easy to dismiss, at least at first. "I had a real bad stomach ache that was going on for about a month," he told Business Insider. "I thought, 'Oh, maybe I ate some sushi, some fish or something that was undercooked.'"

Except food poisoning doesn't typically last for weeks on end, and doesn't leave blood in your stool. He rapidly lost weight, from 175 pounds to 145 in a single summer — without eating less. "I was pretty much like a skeleton," he said.

Lopez went to his doctor, who eventually decided to do a colonoscopy to learn more. That's when they discovered a "grapefruit-sized" tumor in his colon, he said. Lopez saw the scan and couldn't believe his eyes. Colon cancer? He was so young, healthy, and fit.

Stories like Lopez's are increasingly common. Colon cancer rates are rocketing among athletic young people in their 20s, 30s, and 40s, and survival rates are dropping.

Take Chris Rodriguez, a 37-year-old improv actor and CrossFit enthusiast who adheres to a high-fiber, high-protein diet, with plenty of veggies. He was 35 when he was diagnosed with stage 3 rectal cancer.

"The question pops in your mind, 'What else was I supposed to do?'," Rodriguez told BI. "That's really the unfortunate thing with a diagnosis like this, is there isn't really much else that you're supposed to do, outside of looking for symptoms."

The most convenient explanations for the rise in young colon cancer are diet and weight. We know diet can influence colorectal cancer risk, and it's something people can fix, to a degree. Plus, our diets have changed. These days we all consume more sugar, more ultra-processed foods, more oil and butter, while moving less.

Still, doctors say the trend we're seeing now defies neat categories of genetics or lifestyle, and it's baffling. Other factors are clearly messing with our digestive systems, but they're tough to pinpoint. Pollution, microplastics, and artificial light — all are pervasive in society, yet very tricky to study.

Thanks to recent research, we are starting to get a better picture of why young colon cancer cases are rising, and we're on the cusp of some pretty big results that may uncover better ways to prevent and treat it.

Young colon cancer is getting deadlier and more common

Something shifted in the 1960s. Everyone born after 1960 has a higher colon cancer risk than previous generations. This phenomenon is known as the "birth cohort effect."

"The rise that we're seeing cannot just be accounted for by inherited differences," Dana Farber colon cancer researcher Dr. Marios Giannakis told BI.

In the US, young colon cancer rates have been rising about 3% every year since the early 1990s, according to National Cancer Institute data.

"We do think since genetics haven't changed, the cancers that are increasing are environmentally based," Dr. William Dahut, the chief science officer at the American Cancer Society, said during a recent briefing to reporters. "Exactly what's doing it is really — more research is needed."

The biggest cancer centers in the US are opening units to investigate this trend. In 2018, Memorial Sloan Kettering in New York opened a first-of-its-kind center for "young-onset" colorectal cancer patients. Dana Farber in Boston, Mass General, MD Anderson Cancer Center, and Columbia University Irving Medical Center followed close behind, all opening special programs for young colon cancer cases.

In 2021, the CDC took action, lowering the age of recommended colon cancer screening from 50 to 45. It's an effort to catch more young colon cancer cases sooner, upping the odds of people surviving.

It isn't a uniquely American issue. Wealthy countries, in particular, are seeing similar spikes. New Zealand, Chile, Norway, and Turkey are among 27 countries recording record-high rates of young colon cancer.

Diets matter — to an extent

It's hard to dismiss the role our changing food landscape has played. We are undoubtedly eating worse than our grandparents did 100 years ago.

Take fiber, for example. Found in abundance in whole plant foods like beans, it is a nutrient clearly associated with lower risk of cancer.

Some of the most popular foods in US supermarkets — prepackaged for our convenience — tend to have fiber stripped out during processing, and extra salt, sugar, and oils added in to make them more palatable and shelf-stable.

It started in the aftermath of World War II, when industrial processing and factory farming took hold nationwide.

"Essentially we redeployed what had allowed the United States and allies to prevail in that war to non-military applications, and it completely transformed agriculture," Dr. David Katz, a leading expert in chronic disease prevention and nutrition, told BI.

"You only have a certain total number of calories you can eat per day, and if a higher percentage of those is made up of hamburgers and Pop-Tarts, then a lower percentage ipso facto is made up of lentils and all the other good stuff."

Ultra-processed foods now account for a significant proportion of what we eat. Excess sugar, salt, and chemicals lurk in pasta sauce, breakfast cereals, and salad dressing. Brown bread labeled "heart healthy" can have a higher sugar content than white Wonderbread.

Upsetting the balance of nutrients in our guts has consequences. Compounds that aren't necessarily harmful in moderation, like omega-6 fatty acids from seed oils, take up a disproportionate part of our diets. That can lead to inflammation, infection, and diseases like diabetes, heart disease, and, yes, colon cancer.

Your microbiome is not just about what you eat. It's influenced by myriad factors, from how you were born to your work schedule.

What else is going on?

Doctors and lab scientists who spoke to BI for this story all said the rise in millennials getting colon cancer likely won't be attributed to one single thing.

Shuji Ogino, an epidemiology professor at Harvard Medical School, has been studying young colon cancer cases across the world. He published a study in Nature that showed the early life "exposome" — diet, lifestyle, environment, exposures — has changed dramatically, becoming conducive to cancer.

We've introduced lots of new things to our environment without knowing the ramifications. Now, we're starting to see the long-term effects.

Something as simple as artificial light could play a role. "That's something no human being experienced 200 years ago," Ogino said. Lights allow us to work and socialize at all hours, impacting how our body clocks regulate hormones and metabolism.

Dr. Heinz-Josef Lenz, co-lead of the gastrointestinal cancer program at the University of Southern California cancer center, is also studying how the environment may be damaging our DNA in ways we don't yet understand.

His data so far suggests the trend of more younger folks developing colon cancer isn't genetic, but our genes may affect how we respond to our exposures — the processed food we eat, the antibiotics we take, and the polluted air we breathe.

"When you are 16 years old or 20 years old, you cannot blame it on diet or exercise or obesity — it's just too short," he said. "We're just scratching the surface on better understanding the impact of the parents, particularly in the young onset: was their exposure part of it, or not?"

Here are five things we're learning:

1. Sleep cycle

We can't separate gut health from our internal clock.

Gut bacteria help regulate sleep, which cuts cancer risk.

Emerging evidence suggests that disrupting the circadian rhythm creates problems in the gut that can contribute to colon cancer, according to studies in mice and data in humans. Our sleep can be derailed by late schedules and artificial light from our homes and phones, which may be one factor in rising colon cancer cases.

2. Microplastics in air and water

Increasingly, researchers are finding evidence that microplastics play a negative role in fertility.

They can also be pro-inflammatory, driving diseases like cancer and obesity, hurting lungs, and possibly helping cancer to thrive in the body.

A new evidence roundup from researchers at UCSF analyzed 22 studies that compared microplastic exposure to health problems in mice and people, and found that all of them showed some harm.

"We basically saw this continuous effect that the more you get exposed to it, so in our environment, the more it gets produced, the greater the health harm," Nicholas Chartres, one of the study's authors and a former head of the science and policy team at UCSF's program on reproductive health and the environment, told BI.

Chartres says the time is now to act to reduce our microplastic exposure, and it must be done at a policy level. At home, Chartres runs around the house throwing out his kids' plastic toys, but he knows he's playing a losing game of environmental whack-a-mole.

"We don't need to have specific quantification of the level of harm, there's enough here to show that they're certainly contributing," he said.

3. What your parents were exposed to

Lenz is conducting research that aims to unravel why so many Hispanic patients in Southern California seem to be especially at risk of developing early colon cancer.

His team is studying cancer patients' blood, DNA damage, lifestyles, and ZIP codes to pinpoint where their exposure risks might be coming from, whether it be overuse of antibiotics, pollution that families are exposed to, or something else.

"It could be an epigenetic event, not only from the patient itself but from the family, from the parents and their exposure," he said. "Epigenetics can be influenced by lifestyle and by exposure to chemicals, or whatever it is that will actually react."

4. Antibiotics

It is well established that antibiotics disrupt the gut microbiome, killing off some beneficial bacteria. And humans aren't the only antibiotic consumers.

Most of the antibiotics (73%) in use worldwide are for meat production, recent research suggests. Some meat advertised as antibiotic-free has failed independent testing.

Red meat consumption ups a person's colon cancer risk, and so does antibiotic use, but these two factors aren't necessarily separate.

5. C-section

Newborns are exposed to trillions of their mother's microbes as they travel through the birth canal, giving an infant's microbiome an initial boost. Kids who are delivered through the abdomen via cesarean section don't get those same health benefits.

Recent research from Sweden suggests girls who are born via c-section have a higher risk of developing young colon cancer than those born vaginally.

Major colon cancer discoveries coming in 2025-2026

In 2024, a group of international researchers mapped 1.6 million cells in the gut to create the most comprehensive picture to date — the "gut atlas."

"It's rare that any one study squeezes out all the relevant biological insights," Ivan Vujkovic-Cvijin, a professor of medicine at Cedars-Sinai Medical Center, who was not involved in the study, told Business Insider.

"By identifying which components of tissue function are dysregulated in disease, the scientific community can design drugs to restore those functions," he said.

There's more to come. Multiple big, well-funded multinational studies are underway, including a US-UK collaboration that's giving out interdisciplinary cancer grants to teams around the world. The studies are expected to release results this year and next.

2 ways to reduce your risk today

Until we know better what's going on, researchers and clinicians say there are two steps you can take to reduce colon cancer risk.

First, control what you can control.

"Let's focus on the stuff we can change," Dr. Cassandra Fritz, a gastroenterologist and colon cancer researcher at the Washington University School of Medicine in St. Louis, tells her patients.

That means no smoking, regular exercise, less alcohol, reducing your intake of ultra-processed snacks and processed meats, and no sugary beverages — factors directly linked with colon cancer risk. You could also consider microwaving food in glass or ceramic instead of plastic.

Second, know the signs of colon cancer and do not be complacent about them. Many young cases are diagnosed too late, making treatment complicated.

These four symptoms can occur up to 18 months before a colon cancer diagnosis:

• Abnormal diarrhea that lasts for weeks
• Persistent abdominal pain
• Bloody stool (red, magenta, or black)
• Iron deficiency anemia (determined by a blood test)

Don't fear the process of getting checked, experts told BI. Anyone dealing with these persistent symptoms can ask their doctor for a fecal immunochemical test (FIT) that is noninvasive and costs just a few dollars.

"If there are symptoms which could be associated with colon cancer, make sure you get the screening and don't just accept that they're saying 'It's unlikely' or 'I've never seen it,'" Lenz said.

When it's spotted early, colon cancer is a very survivable disease.