Vitamin A5: Evidence, Definitions, Gaps, and Future Directions

Area of Science:

• Biochemistry
• Nutrition Science
• Endocrinology

Background:

• Vitamins are essential micronutrients with established roles in human health.
• The last vitamin was identified 80 years ago, highlighting the novelty of new discoveries.
• The definition of vitamins and vitamin A requires clarification with emerging concepts.

Purpose of the Study:

• To clarify the foundational concepts and definitions of vitamins, particularly vitamin A.
• To introduce and define vitamin A5 as a novel micronutrient.
• To assess the role of vitamin A5 in preventing diet-related and Western lifestyle diseases.

Main Methods:

• Literature review summarizing key findings on vitamin definitions and vitamin A5.
• Analysis of the biochemical pathways involving vitamin A5 precursors and RXR activation.
• Assessment of epidemiological data linking dietary habits to Western lifestyle diseases.

Main Results:

• Vitamin A5 is proposed as an umbrella term for 9-cis-β,β-carotene and 9-cis-13,14-dihydroretinol.
• Vitamin A5 acts as a precursor for 9-cis-13,14-dihydroretinoic acid, an endogenous activator of the nuclear hormone receptor RXR.
• A diet low in vegetables, particularly leafy greens, is linked to Western lifestyle diseases, with vitamin A5 offering a potential mechanistic explanation.

Conclusions:

• Vitamin A5 is a newly identified micronutrient crucial for preventing diet-related diseases.
• Vitamin A5 provides a mechanistic link between low vegetable consumption in Western diets and the prevalence of associated diseases, including neurological and mental health issues.