Probiotics for Anxiety and Appetite in HIV

We knew about the mental health benefits of probiotics in the 1920s, but when Alexander Fleming (pictured above) discovered antibiotics, medicine turned away from the healthy bacteria, only to rediscover them in the early 2000s.

Probiotics may help anxiety in HIV+, but they come with a hidden risk

STUDY: Zandifar A et al, Int J Psychiatry Med 2026;0(0)

STUDY TYPE: Randomized controlled trial

FUNDING: Alborz University of Medical Sciences

Background

Gut microbiome dysbiosis, a known consequence of HIV infection, disrupts the gut-brain axis and may worsen mood and cognition. Probiotics, which restore microbial balance in the gut, have shown promise for psychiatric symptoms in other populations. This trial asked whether they could do the same in HIV.

The Study

• 50 outpatients with HIV in Iran, no active psychiatric disorder at baseline; average age 42–43; 72% men
• Randomized to probiotic capsules (Lactobacillus acidophilus, Bifidobacterium, and Lactobacillus plantarum, 10⁸ colony-forming units twice daily) vs. matched placebo for 12 weeks
• Outcomes = Anxiety scale (BAI), Depression scale (BDI), appetite questionnaire (SNAQ), and Sleep scale (PSQI)

Results

Probiotics outperformed placebo on two of four outcomes: Anxiety and appetite.

Anxiety scores on the BAI dropped steadily in the probiotic group across all four time points, while the placebo group showed little change. The difference between groups was clear by week 4 and continued through week 12.

Appetite scores on the SNAQ rose in the probiotic group from a median of 15 at baseline to 19 at week 12, while the placebo group held flat at 16.

Side Effects

Four patients on probiotics reported mild gastrointestinal symptoms (two diarrhea, two flatulence). Two placebo patients reported flatulence. All resolved within a few days without stopping treatment.

Limitations

Although they had four primary outcomes, the positive results survived a Bonferroni correction for multiple measures (due to the robust p value < 0.001). Still, this is a small trial in patients without a psychiatric diagnosis. Whether probiotics changed the microbiome is unknown.

Practice Implications

1. Though this study builds on more solid evidence for probiotics in anxiety, I wouldn’t jump into probiotics in HIV+ without approval from the infectious disease team.
2. Although generally safe, there is a risk of bacteremia/sepsis, particularly in those with advanced immunosuppression, central venous catheters, or disrupted GI mucosal integrity. However, probiotics reduce inflammation and diarrhea in HIV+, and there is only one case report of a problem. A meta-analysis estimates the spesis risk with probiotics in HIV+ at 1:7,369.
3. For patients who are not immunocompromised, probiotics prevent bacterial overgrowth in most patients (Zhong C et al, J Clin Gastroenterol 2017;51(4):300–311).
4. Here are some combo-products that contain the right strains for mental health and were tested by independent labs.