Why in news?
A study published in January 2026 revealed that all‑trans retinoic acid, a metabolite of vitamin A, can suppress anti‑tumour immune responses by reprogramming dendritic cells. Researchers demonstrated that blocking retinoic acid production enhances the effectiveness of dendritic cell vaccines and could improve cancer immunotherapy. This finding draws attention to the complex roles of vitamin A metabolites in the body.
Background
Vitamin A is a fat‑soluble nutrient stored predominantly in the liver. It occurs in two dietary forms: preformed vitamin A (retinol and retinyl esters) from animal sources such as liver, fish, eggs and dairy products, and provitamin A carotenoids from plant sources like carrots, sweet potatoes, dark leafy greens and yellow fruits. Once ingested, vitamin A supports vision, immune function, reproduction and the maintenance of epithelial tissues. Inside cells, it is converted into retinoic acid, which acts as a signalling molecule regulating gene expression.
Key findings of the study
- Dendritic cell reprogramming: The research showed that dendritic cells exposed to tumour antigens produce high levels of retinoic acid. This, in turn, induces tolerance rather than immunity, dampening the body’s ability to attack cancer cells.
- New therapeutic approach: Scientists developed a drug candidate called KyA33 that inhibits retinoic acid synthesis. In preclinical experiments the drug restored dendritic cell function, improved vaccine efficacy and even reduced tumour growth when used alone.
- Implications: The findings suggest that while vitamin A is essential for health, its metabolites can have opposing effects on immune responses depending on context. This underscores the need for balanced intake and careful consideration in therapeutic settings.
Dietary importance
- Vision and eye health: Vitamin A forms pigments in the retina, supporting night vision and overall visual acuity. Deficiency can cause night blindness and xerophthalmia (dry eyes).
- Skin and mucous membranes: It helps maintain epithelial tissues, protecting against infections and promoting wound healing.
- Immune support: Adequate vitamin A bolsters immune defences by supporting white blood cell function and maintaining the integrity of skin and mucosal barriers.
- Safe intake: While deficiency leads to poor growth and susceptibility to infections, excessive supplementation can cause toxicity. A balanced diet rich in colourful vegetables and moderate animal products meets most people’s needs.
Conclusion
Vitamin A plays a dual role in our bodies: as an essential nutrient for vision and tissue maintenance and as a precursor of signalling molecules that can modulate immune responses. Ongoing research into retinoic acid inhibitors could lead to novel cancer treatments, but individuals should continue to obtain vitamin A through a varied diet rather than high‑dose supplements unless medically advised.
Sources: ScienceDaily
