Killer Bars, Hidden Additives & My Cancer Journey: What Ultra-Processed Foods Are Doing to Us

​When I first entered the world of cancer, food felt both comforting and like a battlefield. The hospitals, scans, and treatments took a toll on my body. During that time, I became acutely aware of what I consumed. It mattered not just in terms of calories and macros, but also in terms of chemical exposure, inflammation, and long-term risks. This led me to scrutinise labels, decode ingredients I could barely pronounce, and view food as either medicine or poison based on its content.

Recently, the discussion around ultra-processed foods has intensified. A few nights ago, I watched Joe Wicks: Licensed to Kill with both fascination and frustration. In that Channel 4 special, Wicks teamed up with Dr. Chris van Tulleken to create a so-called "Killer Bar," a protein snack loaded with 96 legal, but dangerous additives. The aim was to highlight how far we’ve drifted from real food and how many questionable chemicals hide behind so-called health-conscious branding. Critics labeled it sensationalist. Supporters argued it was necessary.

For me, as someone living with cancer, it struck a chord. I've learned that the details we often overlook can be the ones that harm us over time.

This piece explores:

• What ultra-processed foods (UPFs) are and their connection to cancer.
• The ingredients and additives that raise the most concerns.
• What Joe Wicks’ "Killer Bar" revealed and what it didn't.
• The science behind how these substances may promote cancer.
• What I changed, what I learned, and what still frightens me.
• Practical steps anyone can take to eat cleaner without feeling overwhelmed.

1. What Are Ultra-Processed Foods and Why Should We Care?

“Ultra-processed food” is a relatively new term created by scientists using the NOVA classification system. In simple terms, it refers to any product made from industrially extracted ingredients like modified starches, hydrogenated oils, protein isolates, emulsifiers, colorings, and flavorings that you wouldn’t typically have in your kitchen. These foods are designed to be addictive, last a long time, and profit companies – not to nourish our bodies or cells.

Studies show that diets high in UPFs connect to higher rates of obesity, heart disease, metabolic syndrome, and various cancers [1].

A large meta-analysis found that every 10% increase in UPF consumption raised the risk of colorectal cancer by about 4% [2]. The International Agency for Research on Cancer (IARC) confirmed that a higher intake of UPFs was related to increased risks of both cancer and cardiometabolic diseases [3].

A 2023 BMJ study took this further: a 10% rise in UPFs was linked to a 13% higher overall cancer risk and an 11% higher breast cancer risk [4].

Whilst we should note that correlation doesn’t equal causation, Cancer Research UK reminds us that this area of research is young and complicated by lifestyle factors. Smokers and those who are inactive or have lower incomes may consume more UPFs for reasons unrelated to the food itself [5]. Yet, even careful scientists are starting to wonder: if it isn’t just about calories, what substances in these foods could be causing harm?

2. The Hidden Ingredients That Could Be Harming Us

Emulsifiers

Emulsifiers help water and oil mix. They create a smooth texture in ice cream, chocolate, protein shakes, and some nut milks. They also make mass production easier but may make it harder for your gut to handle these foods.

Studies show that emulsifiers such as carrageenan (E407), mono- and diglycerides (E471), polysorbate 80, and carboxymethylcellulose can harm the gut microbiome, thin the protective mucus lining, and increase inflammation [6][7].

In a significant French study (NutriNet-Santé), participants with the highest intake of mono- and diglycerides had a 15% higher overall cancer risk and up to a 46% higher prostate cancer risk. Intake of carrageenan correlated with increased breast cancer risk [8].

One review put it simply: emulsifiers may cause low-grade inflammation and metabolic issues that contribute to tumor growth [9].

We don’t yet know what amounts are safe for daily exposure, and that’s the point. No one has the answers.

Artificial Sweeteners

Artificial and “non-nutritive” sweeteners like aspartame, sucralose, and neotame are often marketed as healthier sugar alternatives. But the research is mixed. A 2024 review linked heavy long-term use of non-caloric sweeteners to higher risks of cardiovascular disease and depression, and suggested possible metabolic disruption [10].

In July 2023, the WHO’s IARC classified aspartame as “possibly carcinogenic to humans” (Group 2B). The evidence was limited but enough to raise concerns. Joe Wicks used this classification in promoting his “Killer Bar,” deliberately including aspartame to make an impact [11].

The irony? Many “fitness bars” promoted as healthy contain ingredients people like me now try to avoid.

Nitrates, Nitrites, and Nitrosamines

If emulsifiers are new, nitrates are the old troublemakers. Used in processed meats to maintain color and prevent bacterial growth, nitrates can turn into nitrosamines in the stomach – compounds known to cause cancer in lab animals and strongly linked to colorectal cancer in humans [12].

This isn’t up for debate: the WHO classifies processed meats with nitrates and nitrites as Group 1 carcinogens – the same category as tobacco.

Artificial Colors and Preservatives

Certain dyes, like Allura Red (E129), have caused inflammation and DNA damage in animal colon cells [12]. Preservatives like sodium benzoate or butylated hydroxytoluene (BHT) are generally considered “safe” in isolation. However, when included in ultra-processed products, we have almost no data on long-term effects or how they interact.

Acrylamide

Acrylamide forms when starchy foods like chips or toast are cooked at high temperatures. It’s classified as a probable human carcinogen (Group 2A) [13]. While usual intake levels are low, this compound has caused DNA mutations in animal studies. Industrial food processes, which often involve pre-frying or roasting, increase overall exposure.

Packaging Contaminants

Not all dangers are on labels. Many UPFs are wrapped in plastics that release chemicals like bisphenol A (BPA), phthalates, or per- and polyfluoroalkyl substances (PFAS). These “forever chemicals” can build up in the body, disrupt hormones, and have been linked to cancers of the breast, prostate, and liver [14].

We focus so much on “clean eating,” yet the packaging itself can poison the contents.

3. The Joe Wicks “Killer Bar” – Useful Awareness or Fear Campaign?

When Licensed to Kill aired, it created a stir on social media. Joe Wicks, the nation’s fitness coach (and purveyor of rather loud on-screen farts – yes, sorry, it’s always he first thing that comes to mind when I think of Joe, and they say sharing it caring…), collaborated with Dr. Chris van Tulleken to create a protein bar loaded with 96 legal additives – some found in cosmetics, others in processed foods. His claim was simple: “If this bar is legal, something’s wrong with the system.”

The stunt had an impact. The public reacted with horror.

But was it appropriate?

On the one hand, it forced many to recognise a basic truth: we’ve normalised consuming things our grandparents wouldn’t even recognise as food. The show sparked discussions about labeling, additives, and regulations [15].

On the other hand, not everyone agreed. The European Specialist Sports Nutrition Alliance (ESSNA) called it “alarmist,” claiming not all processing is harmful and that casting a negative light on the entire category could confuse consumers [16]. Critics also pointed out Wicks' ties to protein snacks, raising questions about hypocrisy [11].

As a viewer and a patient, I saw both perspectives. Fear rarely drives lasting change, but shock can open minds. Wicks’ bar did that, and perhaps it was necessary. Still, I wished the conversation had progressed from outrage to education.

4. The Science: How Might These Foods Fuel Cancer?

Let’s cut through the complexities. How might these additives contribute to cancer biology?

1. Chronic Inflammation

Low-grade inflammation is a significant ally of cancer. Emulsifiers, refined oils, and artificial additives can irritate gut tissue, leading to cytokine release and immune activation. Chronic inflammation damages DNA, encourages abnormal cell growth, and weakens repair processes.

2. Gut Microbiome Disruption

Emulsifiers change the composition of gut bacteria and damage the intestinal barrier [6][7]. This “leaky gut” effect allows bacterial toxins (like lipopolysaccharides) into the bloodstream, activating the immune system and possibly creating an environment conducive to tumor growth.

3. Hormone Disruption

Chemicals like BPA and PFAS mimic or interfere with natural hormones. For cancers sensitive to hormones, such as breast, prostate, and ovarian cancer, these disruptions can lead to long-term problems [14].

4. DNA Damage

Compounds like acrylamide and nitrosamines can directly harm DNA, leading to mutations that, if unrepaired, may initiate cancer [13][12].

5. Metabolic Stress

UPFs are high in calories but low in nutrients, leading to insulin resistance and obesity – both independent risk factors for many cancers. A metabolically unhealthy body is predisposed to disease.

6. The Cocktail Effect

This may be the biggest unknown. Regulators test additives individually, at isolated doses. Yet in reality, we consume hundreds of them each day, interacting within our bodies' complex systems. Science has barely started to explore the combined effects of this chemical mixture.

5. My Path, What I Changed, What I Learned, and What Still Scares Me

When I was diagnosed, I felt powerless over almost everything, except my diet. That became the one area I could actively influence.

What I Changed

• I learned to read every label. If I can’t pronounce an ingredient, it doesn’t go in the basket.
• I swapped commercial protein bars for homemade ones made with nuts, seeds, and fiber syrup.
• I focused on whole, fibrous foods: cruciferous vegetables, berries, and fermented foods.
• I limited “healthy” packaged foods, as most are just ultra-processed with better branding.
• I started cooking more from scratch, which made me realise how complicated we’ve let eating become.

What I Learned

• “Natural flavoring” is often anything but natural.
• You can’t rely on marketing; even “organic” or “high-protein” products may have multiple emulsifiers.
• Reducing ultra-processed foods improved my digestion, sleep, and energy. I can’t prove it, but I feel it.

What Still Scares Me

• Cumulative exposure: the silent build-up of additives and contaminants.
• Packaging toxins: invisible, unlabeled, and impossible to fully avoid.
• Recurrence risk: if cancer comes back, will my past habits have contributed?

Still, I’d rather act on incomplete information than wait for perfect proof. For me, caution is empowerment.

6. How to Eat (and Live) Better Without Fear

Label Red Flags

• More than 10 ingredients in a simple food.
• Names ending in “-ate,” “-ose,” or “gum.”
• Emulsifiers, stabilisers, flavorings, or “natural flavors.”
• Artificial sweeteners like aspartame or sucralose.
• Nitrates, nitrites, or processed meats.
• Multi-layered or metallic packaging.

Better Swaps

• Snack on nuts, seeds, or fruit instead of protein bars.
• Make your own nut or oat milk (just water, nuts, blend, strain).
• Replace ready meals with batch-cooked soups, stews, and grain bowls.
• Flavour food with herbs, citrus, or spices instead of packet sauces.
• If you must buy processed, choose frozen whole foods (plain peas, vegetables, fish) rather than packaged meals.

Protective Foods

• Cruciferous vegetables: broccoli, kale, cauliflower – rich in sulforaphane and indoles, which support detox pathways.
• Berries and citrus: full of antioxidants and polyphenols.
• Fermented foods: kimchi, sauerkraut, miso for gut health.
• Healthy fats: extra virgin olive oil, nuts, and seeds – natural anti-inflammatories.

Beyond the Plate

Sleep, movement, and stress reduction are as important as diet. Chronic stress disrupts gut function and hormones, worsening the same pathways that ultra-processed foods affect. I’ve learned that no diet outperforms inner calm.

7. Pulling It Together

Cancer takes control away, and food can give some of it back. I’m not saying every biscuit or protein bar is a death sentence, but I am saying that knowledge matters.

Every label I read now feels like a small act of rebellion. Each home-cooked meal fights against an industry that thrives on ignorance.

The “Killer Bar” stunt might have been dramatic, but maybe that’s what it took to wake people up. It reminded us that just because something is legal doesn’t mean it’s safe.

Start small. Read one label. Swap one product. Cook one meal. That’s how change begins – not with guilt, but with awareness.

In the end, for me, it isn’t just about satisfying hunger. It’s about getting rid of Dave – and anything else that doesn’t belong in my body.

​References

1. University of California, Davis. “Ask the Experts: Ultra-Processed Foods and How They Impact Our Health.” https://research.ucdavis.edu/ask-the-experts-ultra-processed-foods-and-how-do-they-impact-our-health/
2. Romagnolo DF et al. Frontiers in Nutrition (2023). “Ultra-Processed Food Intake and Cancer Risk: Meta-Analysis.” https://pmc.ncbi.nlm.nih.gov/articles/PMC10285062/
3. International Agency for Research on Cancer (IARC). “Ultra-Processed Foods Associated with Increased Risk of Cancer and Cardiometabolic Multimorbidity.” https://www.iarc.who.int/news-events/ultra-processed-foods-are-associated-with-increased-risk-of-cancer-and-cardiometabolic-multimorbidity/
4. Adjibade M et al. BMJ (2023). “Association Between Ultra-Processed Food Consumption and Cancer Risk.” https://pubmed.ncbi.nlm.nih.gov/37087831/
5. Cancer Research UK. “Are Ultra-Processed Foods Linked to Cancer?” https://news.cancerresearchuk.org/2024/04/18/are-ultra-processed-foods-linked-to-cancer/
6. Viennois E et al. Nutrients (2024). “Emulsifiers and Intestinal Health.” https://pubmed.ncbi.nlm.nih.gov/38388570/
7. Chassaing B et al. Cell Metabolism (2020). “Dietary Emulsifiers and Microbiota-Mediated Inflammation.” https://pubmed.ncbi.nlm.nih.gov/32626902/
8. Julia C et al. PLOS Medicine (2024). “Food Emulsifiers and Cancer Risk: Results from the NutriNet-Santé Cohort.” https://journals.plos.org/plosmedicine/article?id=10.1371%2Fjournal.pmed.1004338
9. MDedge. “Are Food Emulsifiers Associated with Increased Cancer Risk?” https://www.mdedge.com/oncologypractice/article/267979/preventive-care/are-food-emulsifiers-associated-increased-cancer
10. Bakaloudi DR et al. Critical Reviews in Food Science and Nutrition (2024). “Health Effects of Artificial Sweeteners.” https://pubmed.ncbi.nlm.nih.gov/38423749/
11. Marie Claire UK (2025). “Joe Wicks: Licensed to Kill.” https://www.marieclaire.co.uk/life/health-fitness/joe-wicks-licensed-to-kill-show
12. Rojas AL et al. Cancers (2023). “Nitrites, Nitrosamines and Colour Additives in Processed Meat.” https://pmc.ncbi.nlm.nih.gov/articles/PMC9905956/
13. Wikipedia. “Acrylamide.” https://en.wikipedia.org/wiki/Acrylamide
14. The Guardian (2025). “Ultra-Processed Food, Forever Chemicals, and Rising Cancer Rates.” https://www.theguardian.com/science/2025/jan/26/ultra-processed-food-forever-chemicals-declining-birth-rates-whats-behind-rising-cancer-in-the-under-50s
15. The Guardian (2025). “Joe Wicks: Licensed to Kill Review.” https://www.theguardian.com/tv-and-radio/2025/oct/06/joe-wicks-licensed-to-kill-review-protein-bars-channel-4
16. New Food Magazine (2025). “ESSNA Responds to Joe Wicks’ Ultra-Processed Foods Comments.” https://www.newfoodmagazine.com/news/256404/essna-response-joe-wicks-ultra-processed-foods/