Acidic Phytocannabinoids as Endocannabinoid System Vitamers: A Formal Nutritional Hypothesis and Its Failure Conditions

This manuscript advances a formal, falsifiable nutritional hypothesis: that acidic phytocannabinoids (Δ9-tetrahydrocannabinolic acid, cannabidiolic acid, cannabigerolic acid, and related family members) constitute a candidate vitamer family supporting endocannabinoid system (ECS) receptor-level function. We apply the eight standard criteria for vitamin classification to this compound class directly, rather than by analogy, and report the result plainly: three criteria are met, one is partially met, one is undetermined, and three — the essentiality cluster — are not met, and fail together for a single, nameable reason: no deficiency phenotype has yet been characterized. We show that the class's actual pharmacology is state-dependent and self-limiting rather than agonist-like (enzyme inhibition at COX-2, receptor potentiation at 5-HT1A, weak partial agonism at TRPA1, and partial selective modulation at the nuclear receptor PPARγ), that this profile is consistent with nutrient-style normalization rather than drug-style agonism, and that it generates a specific, testable prediction distinguishing the two: effect size proportional to baseline deviation from set-point, not to dose. We draw on historical precedent — the classification of vitamin D despite endogenous synthesis, the shared nuclear-receptor mechanism class of vitamin A, and the declassification of vitamin F (essential fatty acids) on grounds of quantity rather than essentiality — to show that each of the paper's open questions has a documented analogue elsewhere in vitamin history. We do not claim these compounds are vitamins. We specify what would need to be shown for that claim to become assessable, and what result would close the question in the negative. KEYWORDS Acidic phytocannabinoids; endocannabinoid system; endocannabinoidome; vitamer classification; nutritional hypothesis; THCA; CBDA; PPARγ; amorfrutins; nuclear receptor agonism; conditional micronutrients; falsifiability; nutritional biochemistry