The Wellness Brew - Issue 24

The rise of colorectal cancer in younger adults has been covered widely enough that you've probably seen the headlines. What’s frustrating is that no one has been able to hone in on what’s causing it, and the honest papers say so directly. This issue will attempt to highlight which risk factors are worth acting on and what screening actually looks like. 

But first, we filtered the noise — here's what's worth knowing this week.

A study published Monday in JAMA Internal Medicine analyzed more than 12 million death certificates across 500-plus occupations and found flight attendants had the highest proportion of deaths from radiation-related cancers, with pilots second. Both ranked above people who work directly with radioactive materials. Flight attendants had roughly 50% higher odds than the general working population, pilots about 36%. In absolute terms that's 6.9% of flight attendant deaths, or about 1 in 14. The detail that makes it convincing: neither group showed elevated death rates from cancers unrelated to radiation, which points toward cosmic radiation at altitude rather than lifestyle or income. This is a study of people who spend their working lives at 35,000 feet, not people who fly for work a few times a month. Nobody is suggesting you cancel a trip. But if you're crew, or you're close to someone who is, it's an argument for taking occupational radiation limits seriously. — Jena et al., JAMA Internal Medicine, 2026.

Pesticide exposure at work and ALS risk

A systematic review in Occupational & Environmental Medicine pooled decades of studies and found workplace pesticide exposure associated with a 60 to 70% higher risk of ALS. Men who'd been exposed were roughly twice as likely to develop it. However, no increased risk showed up in women. One thing worth being precise about. This is occupational exposure, meaning applicators, farm workers, and people handling concentrated product, not the residue on grocery store produce. The takeaway is narrower than the headline: if pesticides are part of your job, protective equipment matters more than the label suggests. — Labrèche et al., Occupational and Environmental Medicine, 2026.

Another wellness brand joins a candy company

Ferrero, the Italian conglomerate behind Nutella and Kinder, announced last week it's acquiring Purely Elizabeth, the Boulder-based granola and oatmeal brand. Forbes reported the price at roughly $800 million. Founder Elizabeth Stein will stay on as CEO and the brand will continue to operate as a standalone business, which is the same structure most of these deals use. This is the second acquisition we've flagged this month after Procter & Gamble agreed to buy Thorne. The pattern is consistent: rather than build health-forward brands from scratch, the food and CPG giants are buying the ones that earned consumer trust the slow way. Whether ingredient standards hold up afterward is an open question, not a foregone conclusion. Same advice as with Thorne. Don't switch brands on news of a deal, but do re-read the ingredient panel in twelve to eighteen months. — Forbes, August 2026.

Colorectal cancer is now the leading cause of cancer death in adults under 50. The rise has gotten a lot of coverage. What to actually do about it has gotten far less.

This is a real trend and it deserves attention, not alarm. Most people reading this will never get colorectal cancer. But for someone out there, this will be worth reading.

An estimated 158,850 Americans will be diagnosed with colorectal cancer this year, and 55,230 will die from it. [1]

The overall number has been falling for decades. That's the good news. But the trend has split in two. In adults 65 and older, incidence and mortality are both dropping by more than 2% a year. In adults aged 20 to 49, incidence is climbing about 3% a year. [2] Mortality in the under-50 group has been rising roughly 1% annually since 2004. [1]

While it used to rank fifth, colorectal cancer is now the leading cause of cancer death in adults under 50. [3]

Rectal cancer in particular is driving it. After decades of decline, rectal cancer incidence started rising again by about 1% a year from 2018 to 2022, and it now accounts for roughly a third of all colorectal cancer cases, up from a quarter in the mid-2000s. [1]

Some perspective, because the percentages sound scarier than the underlying numbers. Lifetime risk is roughly 1 in 25 for men and 1 in 26 for women, and most of that risk still sits in older age brackets. A 3% annual increase compounds on a small base. So while the trend is real and worth acting on, it is not a reason to spend your week worried.

Researchers describe what's happening as a birth-cohort effect. Risk tracks with when you were born rather than age. People born after 1950 carry a higher underlying risk of colorectal cancer than the generations before them, and that elevated risk is following them as they age. [1] [4]

What this observation does is rule certain theories out.

Better detection can’t be the cause of rising incidence. Screening typically starts at 45 or 50, so increased screening can't explain rising rates in people in their thirties. [4]

It isn't something that happens to you in middle age. Whatever this is, it reached people early in life and has been traveling with them since.

And it isn't rare or individual. It has affected an entire generation, across multiple countries, which points at something broad in the environment or the food supply rather than an unlucky subset.

Rebecca Siegel, who led the American Cancer Society's 2026 report, put it about as plainly as a scientist can: the risk of dying from this is climbing in younger generations, confirming a real uptick in disease because of something we're doing or some other exposure. [5]

Nobody knows what that something is. Every serious paper on this says so directly. The pooled European cohort analysis opens by stating the causes remain unclear. The genome-wide association work says explanations are currently lacking. 

What we do have is a list of candidates, and they aren't equally supported.

Worth separating these into tiers, because they get flattened into one list constantly.

Established.

Family history is the single strongest signal on this list. Meta-analyses focused on early-onset colorectal cancer put the increase somewhere between four and six times for people with a first-degree relative who's had it. [21] The estimates vary and the confidence intervals are wide, but they all land well above the roughly two-fold figure usually quoted for the general population. That's the one that should send you to a doctor rather than to a list of dietary swaps.

Inflammatory bowel disease — Crohn's or ulcerative colitis — carries roughly a four-fold increase, and risk scales with how long you've had it and how much of the colon is inflamed. [21] If you have either, you're already on a different screening schedule than everyone else, and that schedule is the thing to keep.

Processed meat is classified by the International Agency for Research on Cancer as a Group 1 carcinogen, and colorectal cancer is specifically the cancer the classification is based on. Every 50 grams a day, roughly one hot dog or a few slices of deli meat, is associated with about an 18% higher relative risk. [6]

Two things to hold at once. The Group 1 label reflects how confident researchers are that it causes cancer, not how much it raises your risk. In absolute terms, that 18% moves a lifetime risk of roughly 5% to roughly 6%. [7]

The proposed pathway is reasonably well worked out. The nitrites used to cure and preserve meat react with proteins in your gut to form compounds that damage the cells lining your colon. Red meat contains a form of iron that speeds that reaction up. And cooking meat at high heat, especially charring it, creates a separate set of harmful compounds on the surface. [7] Animal work supports it: rats fed nitrite-cured ham developed more precancerous colon lesions than rats fed the same ham without nitrite. [8]

Alcohol is also a Group 1 carcinogen, and the association with colorectal cancer holds at levels most people consider unremarkable. A dose-response meta-analysis found the link becomes clear above roughly one drink a day. [23] A 2023 review looking specifically at light-to-moderate drinkers still found elevated colorectal risk in that band, and concluded there's no threshold below which the risk disappears. [22]

Probable.

Mendelian randomization analysis, which uses genetic variants to get closer to causation than observational data can, found probable causal links between early-onset colorectal cancer and body fat percentage, waist circumference, waist-to-hip ratio, fasting insulin, and alcohol intake. [10] A pooled analysis of three large European cohorts found BMI strongly associated with early-onset disease specifically. [11]

Protective.

The 2018 World Cancer Research Fund review found higher intake of fiber, whole grains, dairy, and calcium associated with lower colorectal cancer risk. [12] That's about as close as this field gets to a positive recommendation.

Hypothesized, and genuinely unresolved.

Ultra-processed food as a broad category has been linked to colorectal cancer in some prospective cohort studies and not others. [12] It's a reasonable suspect and it fits the birth-cohort timing. It is not established the way processed meat is, but its rise certainly coincides with the rise in colorectal cancer rates.

Same for antibiotic exposure in childhood, microbiome changes, and sedentary behavior starting young. All plausible, all consistent with the cohort pattern, but unproven.

There really isn’t a perfect risk profile outside of certain gene variants. 

Hereditary cancer syndromes account for a chunk of early-onset cases. A Mayo Clinic analysis found that 27.4% of patients diagnosed under 50 carried an inherited gene mutation known to raise cancer risk, with Lynch syndrome making up 8.3%. [13] Lynch carries a 40 to 80% lifetime colorectal cancer risk and moves fast enough that a new tumor can appear two or three years after a clean colonoscopy. [14]

But roughly three-quarters of young cases are sporadic, with no hereditary explanation at all. Plenty of these patients are fit, active, and eating well.

And family history is a worse filter than people assume. Only about half of young colorectal cancer patients who carry a gene mutation have any colorectal cancer in a first-degree relative. [15] Screening for genetic testing using the standard clinical criteria would miss 28% of Lynch syndrome cases. [14]

So "no family history" doesn't clear you. That's the practical takeaway from all of this, and it's why the next two sections carry more weight than a risk checklist would.

The symptoms are worth knowing: rectal bleeding, a persistent change in bowel habits, stools that are unusually narrow or dark, unexplained weight loss, ongoing abdominal cramping, and iron deficiency anemia showing up on routine bloodwork.

But knowing the symptoms isn't the only failure point. Three out of four colorectal cancers in adults under 50 are diagnosed at an advanced stage. [2] That doesn't happen because young people don't notice rectal bleeding. It happens because they report it and get told it's hemorrhoids, or IBS, or stress, and months pass.

Siegel's own recommendation from the 2026 report was to educate clinicians as well as the public. [5] That's a polite way of saying the dismissal problem runs in both directions.

If you're in that situation, a few things help. Track duration and write it down, because "a few weeks" and "since March" land very differently. Say the words directly: you'd like to rule out colorectal cancer, and you're asking for a referral. If you're told no, ask that the reason be noted in your chart, which tends to change the conversation. And know that being young is not a reason to rule this out. It used to be. It isn't anymore.

The screening age has changed. It's 45 now, not 50. The American Cancer Society moved in 2018 and the U.S. Preventive Services Task Force followed in 2021. [16]

Half of all colorectal cancer diagnoses under 50 are in people aged 45 to 49, who are already eligible for screening. Only 37% of that age group has been screened. [5]

If you have a first- or second-degree relative with colorectal cancer, you start earlier: age 40, or ten years before your youngest affected relative was diagnosed, whichever comes first. [17]

On the options, because the marketing is louder than the evidence:

Colonoscopy is the only one that prevents cancer rather than just finding it, because polyps get removed during the procedure. Sensitivity around 95%, and modeling puts it at more than a 70% reduction in colorectal cancers and more than 75% in deaths compared with no screening. [19] As a screening procedure it's typically covered with no out-of-pocket cost. 

FIT is a stool test you do at home, annually. Around $18. It catches roughly 74 to 79% of cancers but only about 24% of advanced polyps. [18] It’s cheap, easy, and in modeling it performs well, largely because people actually do it.

Cologuard is a stool DNA test, every three years, running about $500 to $680. Catches 92 to 94% of cancers and around 42% of advanced polyps. [18] Better than FIT at detection, but is more expensive and has more false positives.

Shield is the new blood test, added to ACS guidelines in May 2026. Worth understanding what it is and isn't. It detects roughly 8 in 10 cancers and performs poorly on precancerous lesions. List price is $1,495. Stanford modeling put its incidence reduction at 42%, versus more than 70% for colonoscopy and FIT. [19] The ACS explicitly does not list it as a preferred option, and Memorial Sloan Kettering's gastroenterologists don't recommend it for screening. [20]

Two things to take from that. First, there's a real difference between a test that finds cancer and one that prevents it, and the easier options mostly do the first. Second, the best test is still the one you'll actually complete. Shield exists for people who would otherwise do nothing, and for that person it beats nothing.

One detail that undercuts all of the non-colonoscopy options: a positive result requires a follow-up colonoscopy, and the ACS report specifically flags that this follow-up is frequently delayed. A stool test you don't follow up on is a stool test that didn't help.

The cause is unsolved. Your response to it doesn't have to be. Five-year survival for colorectal cancer is 95% when it's caught at a local stage and 15% once it has spread. That gap is the whole story. Lower the risk factors the evidence supports, know the early warning signs, and stay on top of screening. 

Six things you can do this week:

1. Cut processed meat - bacon, deli meat, sausage, etc. This is the one with the strongest evidence behind it, and it's a Group 1 carcinogen for this specific cancer. You don't need to eliminate it. The risk is dose-dependent, so moving from daily to occasional does real work. Bacon at brunch on Sunday is a different exposure than a deli sandwich five days a week.

2. Work on the metabolic side. Waist circumference, body fat, and fasting insulin came out of the causal analysis, which makes them more actionable than most things on a risk list. Muscle mass, movement, and sleep all feed into that, and we've covered each of them.

3. Add fiber, whole grains, and calcium. These are the protective factors with the best support, and they're additive rather than restrictive, which makes them easier to sustain.

4. Drink less. Alcohol shows up in both the established list and the causal analysis.

5. Get screened at 45, or 40 with family history. If a colonoscopy is the barrier, do a FIT test. It's eighteen dollars and it's meaningfully better than nothing. Then actually follow up if it comes back positive.

6. Go in if something is wrong, and keep going. Being young is not a reason for anyone to rule this out or ignore. 

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Wellness, filtered.

The Wellness Brew

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Disclaimer: The Wellness Brew is for informational purposes only and does not constitute medical advice. The content published here is not intended to diagnose, treat, cure, or prevent any disease or health condition. Always consult a qualified healthcare professional before making any changes to your diet, supplement routine, or lifestyle.