Berry tablets, and a bowel cancer inflammation marker that fell by three-quarters before treatment even began. The catch: no cancer patient in the study went without the tablets

C-reactive protein, or CRP, is a blood marker that rises with inflammation. In bowel cancer, higher levels go along with bigger tumours, poorer nutrition and worse outcomes, according to the studies these authors cite. It's also cheap and routine. So when a small Polish study reports the typical CRP reading falling by about three-quarters after three weeks of berry tablets, before any cancer treatment had started, you want to read on. You should also read the authors' own conclusion, which is more careful than that sentence: their results can't show the tablets caused anything.

The study, published in Nutrients on 29 October, ran at the Tarnów Oncology Centre between May 2023 and December 2025. It enrolled 50 people with colorectal cancer, stages II to IV, average age about 70, at their first outpatient visit. Each was to take five tablets three times a day for 21 days, which is 315 tablets by our count. The tablets were compressed freeze-dried whole black raspberry and strawberry, made for the study at Jagiellonian University. The authors estimate they gave 600 to 700 mg of anthocyanins a day, the purple-red plant pigments, though that figure wasn't measured in these batches. People in a large European study averaged about 20 to 65 mg of anthocyanidins a day from food, not an exact like-for-like measure, but it gives a sense of how far above ordinary eating this was.

Blood was taken at the start, at week 4 and at week 12. Among the 43 people with all three CRP results, the median went from 20.44 to 5.22 mg/L at week 4, then 3.00 at week 12 (p below 0.001). The week 4 sample is the interesting one, because it came about a week after the tablets ended and before surgery, chemotherapy or radiotherapy began. Whatever moved CRP by then, it wasn't cancer treatment.

That doesn't make it the berries. Everyone with cancer took the tablets and everyone knew it, so nobody can say what CRP would have done anyway in those weeks between diagnosis and treatment. The 20 people without cancer were only measured once, at the start. Infections, antibiotics, steroids and anti-inflammatory painkillers weren't systematically recorded, and neither was diet. CRP is also jumpy. Among those 20 people, readings ran from 0.6 to 99.58 mg/L.

Look past the median and the picture gets less tidy. The mean fell from 28.19 to 19.87 mg/L at week 4, which is about 30% rather than 74%, and a quarter of patients were still above 36 mg/L. By week 12, CRP had fallen in 72.1% of patients, so it hadn't in the other 27.9%. One person's reading rose by 114 mg/L, and the highest value at week 12, 188.11, was about double the highest baseline among these 43. Seven of the 50 are missing from the analysis, including the person with the highest starting value in the whole group, 122.52. People who miss visits during cancer care may not be doing as well as those who come back, though the paper mentions only missed visits and unavailable samples.

The size should give pause too. A 2020 meta-analysis of 32 randomised trials, one the authors cite, found anthocyanins lowered CRP by an average of 0.33 mg/L. That's a pooled figure from mixed groups of people, and the two numbers aren't calculated the same way, but a median fall of about 15 points is a different order of thing. The authors say themselves that the supplement can't take credit for the whole of it. When a change is far bigger than controlled trials would predict, it's fair to suspect something else is at work.

The rest of the blood panel offers little support. Twelve markers were tracked, with no correction for testing that many. Eight didn't change significantly, including IL-1β, IL-8, IL-10 and VEGF. Of the other three that moved, IL-1α, TNF-α and IL-6, none differed between the start and week 4. Their differences appear only at week 12, some nine weeks after the last tablet and in the middle of treatment. And IL-1α and TNF-α signals sat below the assay's lowest standard, so those are relative signals, not measured concentrations. People with the highest starting CRP fell the most (correlation 0.80), but the authors warn that's what you'd expect from arithmetic and regression to the mean.

What the study can fairly claim is more modest. Older patients could mostly manage the tablets: 37 of 47 rated tolerability as good, and 38 of 50 had no complaint. It also suggests a neat next step, by our reading. Those few weeks before treatment are a natural window, so a trial could give half the patients a placebo and simply compare week 4. A small double-blind trial of anthocyanins with curcumin, in 35 people with bowel polyps, found no significant difference in inflammatory markers between its treatment arms. Note too that despite "undergoing treatment" in the paper's title, the tablets stopped before treatment began, so this says nothing about taking them during chemotherapy. And the authors warn against stretching it to berries in your ordinary diet. Enjoy them for other reasons.