Galacto-oligosaccharides and the aging gut immune system
What it found
In older people, galacto-oligosaccharides increased beneficial gut bacteria and immune markers in the small number of trials done.
Most evidence comes from animals and lab tests.
What they found
Studies in people
Gut bacteria changes
In older people, galacto-oligosaccharides increased Bifidobacterium, Lactobacillus-Enterococcus and Clostridium coccoides-Eubacterium rectale. One study found more Bacteroides and Bifidobacterium along with higher lactic acid in stool.
Immune markers in elderly
One trial in people aged about 69 found that galacto-oligosaccharides increased phagocytosis and natural killer cell activity. It also lowered proinflammatory cytokines IL-6, IL-1β and TNF-α, and raised anti-inflammatory IL-10.
Tolerability and side effects
Common side effects include bloating and digestive discomfort, which increase with higher doses. Daily doses of 5 to 20 grams were tolerated by adults without significant side effects.
Responders and nonresponders
People respond differently to galacto-oligosaccharides based on their diet, gut bacteria and genetics. Those with lower initial butyrate in stool may respond better.
Animal and lab studies
Gut barrier in aged mice
In aged mice, galacto-oligosaccharides reduced leaky gut and increased mucus thickness and MUC2 expression. Lab tests in Caco-2 cells showed protection against permeability damage.
Studies in people and animals
Infection and vaccine effects
Galacto-oligosaccharides reduced respiratory infections in infants and diarrhea in adults. In older people, fermented milk with galacto-oligosaccharides boosted influenza vaccine protection, and in mice it improved immune responses to the vaccine.
What the authors conclude
“The positive clinical outcomes associated with GOS suggest that it could be a feasible approach to support immune health and address the health challenges associated with aging.”
Also in their conclusions
- They say that galacto-oligosaccharides could be a feasible approach to support immune health in aging.
- They urge further research specifically in older adults to understand the mechanisms and develop guidelines.
- They note that the dose, purity and source of galacto-oligosaccharides need more study.
How it was done
As people age, their immune system weakens and their gut bacteria change. The authors wanted to see if galacto-oligosaccharides could help restore immune function in older adults.
They reviewed existing studies on galacto-oligosaccharides and gut health, including trials in infants, adults and older people, plus animal and lab experiments. Only 2 clinical trials have focused solely on older adults.
What it can’t tell you
- Most studies in older people used galacto-oligosaccharides combined with other prebiotics or probiotics, so the effect of galacto-oligosaccharides alone is unclear.
- The long-term effects and sustainability of benefits are not known.
- Animal and lab results may not apply to people.
Who paid
- Conflicts
- Conflict of interest The authors report no conflicts of interest.
- Authors work at
- University of North Carolina, United States; North Carolina State University, United States; King Saud University, Saudi Arabia
The paper
- Title
- Galacto-Oligosaccharides and the Elderly Gut: Implications for Immune Restoration and Health
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Licence
- CC BY. Words in quotation marks are the authors’; the rest is our summary.
- Cite
- Hu Y, Aljumaah MR, Azcarate-Peril MA (2024). Galacto-Oligosaccharides and the Elderly Gut: Implications for Immune Restoration and Health. Advances in nutrition (Bethesda, Md.). doi:10.1016/j.advnut.2024.100263Free full textPubMed 38897384DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error