GLOSSARY

Vitamin-Like Compound is a descriptive label for compounds with related biological functions, not proof of essentiality or formal vitamin status.

For a compound marketed under a historical vitamin number, check its actual identity and accepted classification; old numbering proves no requirement.

The water- versus fat-soluble classification helps explain absorption, transport and storage, but is not an absolute rule for every member. A, D, E and K are fat-soluble; B vitamins and C are water-soluble. Group membership alone cannot determine individual requirements, supplement risks or elimination rates without considering the particular vitamin.

Choline is essential but is not usually counted among the thirteen vitamins, sometimes appearing beside vitamin-like compounds. Endogenous synthesis does not cover every circumstance. Its phospholipid, neurotransmitter and methyl-group roles are connected, but another B vitamin cannot simply replace a choline shortfall. Classification should distinguish an essential nutrient from a conventional vitamin label rather than treating the names as interchangeable.

Vitamins are organic compounds needed for normal function, not directly countable energy sources like fat or carbohydrate. Some participate in energy-releasing reactions, but that does not mean they contain dietary energy or generate fuel independently of food. Athletes need adequate vitamins alongside sufficient energy and macronutrients to use their fuels effectively.

Vitamin needs vary with age, life stage and circumstances; a population reference is not a personalised prescription. More training does not automatically multiply the need for every vitamin. Eating more to meet energy demand often also increases vitamin intake. Food quality and actual restrictions should therefore be assessed before assuming a supplement is necessary.

Betaine, or trimethylglycine, can arise from choline oxidation and contributes methyl donation and osmotic regulation. Anhydrous betaine and digestive-product betaine hydrochloride are not interchangeable in application or amount. Sporting findings depend on protocol and participants; methyl-donor status does not guarantee strength, fat-loss or choline-deficiency treatment benefits for everyone, nor make the different formulations equivalent.

Check supplement amount per serving, daily servings and units; a vitamin name alone does not specify exposure. Combining a multivitamin, single-vitamin product and fortified drink requires adding their contributions. Therapeutic doses for defined conditions cannot automatically become routine prevention for healthy athletes, and larger package numbers do not establish better outcomes.