Can Phytochemicals and Probiotics Slow Ageing? New Clinical Trial Results

A newly published double-blind, randomised, placebo-controlled trial has found that boosting dietary phytochemicals and Lactobacillus probiotics significantly improved key biological markers of longevity in older men. The study, published in April 2026 in the Journal of Ageing and Longevity, used the phytochemical supplement YourPhyto and the probiotic YourGutPlus+ and the results provide some of the strongest clinical evidence yet that targeted nutritional supplementation can meaningfully influence the ageing process.

What the study set out to investigate

As men age, a predictable set of physiological changes occurs: systemic inflammation rises, testosterone levels fall, and grip strength. A well-established proxy for overall physical fitness, cognitive health and longevity tends to decline. While the role of diet and gut health in influencing this trajectory has been recognised in observational research, fewer controlled trials had prospectively tested whether these markers could actually be improved through nutritional intervention in an elderly population.

This phase II randomised controlled trial, conducted at Bedford Hospital as part of the Cambridge University Hospitals network, aimed to fill that gap. The research team, drawing on expertise from the University of Bedfordshire, the University of California San Francisco, and Edith Cowan University in Australia, recruited 208 men with untreated early-stage prostate cancer under active surveillance. With an average age of 74 years, this was an ideal cohort for studying markers of longevity in an older, non-athletic population.

How the trial was designed

All 208 participants received two capsules per day of the phytochemical-rich supplement YourPhyto, containing concentrated broccoli, green tea, pomegranate, ginger, cranberries and turmeric. They were then randomised in a double-blind fashion to receive either a five-blend Lactobacillus probiotic capsule YourGutPlus+ or an identical-looking placebo. The probiotic arm contained 10 billion colony-forming units of Lactobacillus rhamnosus, Lactobacillus plantarum, Lactobacillus paracasei, Lactobacillus bulgaricus and Lactococcus lactis, alongside prebiotic inulin and vitamin D3.

The primary endpoint was grip strength, measured at baseline and at four months. Secondary endpoints included systemic inflammation as measured by the neutrophil-to-lymphocyte ratio (NLR) and serum testosterone levels at four months.

What the results showed

Grip strength

All participants who took YourPhyto regardless of whether they received the probiotic or placebo — showed a statistically significant improvement in grip strength over four months. Those taking YourPhyto alone improved by an average of 2.5 kg, representing an 8% gain. However, in the group that took YourPhyto together with YourGutPlus+, grip strength improved by an average of 4.4 kg an 11% gain and a 57% greater improvement compared to the phytochemical-only arm. The odds of grip strength improving were 11.8% greater in the combined supplement group.

Inflammation

The neutrophil-to-lymphocyte ratio a cost-effective surrogate marker for systemic inflammation moved in opposite directions in the two groups. In the YourPhyto-only arm, NLR increased slightly on average over four months. In the combined YourPhyto plus YourGutPlus+ arm, NLR decreased. The difference between the two arms was statistically significant, providing direct evidence of the anti-inflammatory synergy between phytochemicals and probiotics.

Testosterone

At four months, average serum testosterone was 12% higher in the group taking YourPhyto combined with YourGutPlus+ compared to those taking YourPhyto alone. Both groups remained within the normal range, and importantly, despite the higher testosterone levels in the combined group, the separately reported cancer outcomes showed no increase in prostate cancer progression a reassuring safety finding.

Safety and tolerability

The supplements were very well tolerated across the full cohort. One participant reported mild indigestion. Four participants reported that their bowel function had actually improved. There were no significant changes in liver function or other blood parameters.

Why does combining phytochemicals and probiotics make a difference?

The results support a biological principle that has been building in the scientific literature: phytochemicals and probiotic bacteria work in genuine synergy. Phytochemicals from foods such as pomegranate, cranberry, broccoli and green tea act as prebiotics feed and support beneficial gut bacteria. In return, probiotic bacteria break down phytochemicals into more readily absorbed, bioactive compounds, increasing their effectiveness in the body.

The anti-inflammatory properties of phytochemicals including curcumin from turmeric, epigallocatechin gallate from green tea, and quercetin from cranberries are well established in the laboratory. This trial adds clinical evidence that these mechanisms translate into measurable improvements in human biomarkers, even in a population aged on average 74 years.

The testosterone finding is particularly noteworthy. Previous research has linked gut microbiome health with testosterone levels in elderly men, and this trial provides prospective randomised evidence of that relationship with higher testosterone in the probiotic arm correlating with both better gut health and improved grip strength.

What makes this trial significant

The authors note that, to their knowledge, this is the first double-blind randomised controlled trial to demonstrate that a combined dietary intervention boosting both phytochemical-rich foods and Lactobacillus probiotics improved strength in a non-athletic, elderly population. Previous studies on phytochemicals and strength had largely been conducted in younger athletes. This trial extends those findings to a group far more representative of the people who may benefit most.

The study was conducted to the highest ethical and methodological standards approved by the UK National Ethics Committee, independently audited, and registered with the ISRCTN clinical trials registry. The supplements were manufactured to Good Manufacturing Practice (GMP) standards, with every batch independently tested for heavy metals, pesticides and microbial contamination. Importantly, the manufacturers YourPhyto and YourGutPlus+ had no editorial input into the study design, analysis or publication.

What this means for healthy ageing

Grip strength is not merely a measure of how hard someone can squeeze. It is one of the most consistent predictors of overall health span in the scientific literature, correlating with inflammation levels, bone density, cognitive function, cancer risk, depression and falls in older adults. A clinically significant improvement in grip strength in just four months particularly in men in their mid-seventies is a meaningful result with real-world implications for independence and quality of life.

For those looking to support healthy ageing through evidence-based nutritional strategies, the combination of YourPhyto and YourGutPlus+ now has three published clinical trials behind it: the national Covid-19 nutritional intervention study, the prostate cancer progression trial published in European Urology Oncology, and this longevity study in the Journal of Ageing and Longevity. No comparable nutritional combination has achieved this level of peer-reviewed clinical backing.

What comes next

The authors call for larger, longer-term randomised studies to confirm these findings using more definitive end points such as morbidity and mortality. They also highlight the need for more diverse ethnic representation in future trials, as this cohort was drawn primarily from the Bedford and Cambridge areas. Additional measurements including baseline testosterone, more granular inflammatory markers such as CRP and IL-6, and formal quality-of-life assessments are recommended for subsequent research.

In the meantime, these results add a third peer-reviewed pillar to the evidence base for combining phytochemical-rich supplementation with targeted probiotic support as a practical, safe, and clinically meaningful strategy for supporting healthy ageing in older adults.

Citation

Thomas RJ, Williams M, Aldous JWF, Kenfield SA, Newton RU. The Effect of Boosting Dietary Lactobacillus and Phytochemical Rich Foods on Biomarkers of Longevity - A Phase II Randomised Placebo Controlled Trial. Journal of Ageing and Longevity. 2026; 6(2):35. https://doi.org/10.3390/jal6020035