Chemistry, Skin becomes Realities

Nutrition is a different science; chemistry its own. What if I turn the concept of Vitamin D to a chemical reality. Vitamin D ~ Calcium

two main forms, vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol)

ergo--?--calciferol, a form of calcium {an element}? chole-cholesterol (a nutrition term) Cal (calcium}...calcification

A sterol-like structure features a core of four hydrocarbon rings (the steroid nucleus), with a hydroxyl (-OH) group providing polarity, making it amphipathic and a side chain. 

Amphipathic (of a molecule, especially a protein) having both hydrophilic and hydrophobic parts.

Makes sense, love and hate; tearing apart--indecision

Not good for anatomy

photochemical reaction in the skin followed by metabolic activation in the liver and kidneys

Darn, we've entered into Quantum Physics; back to Nutrition (the abstraction):

Vitamin D impacts the absorption of calcium that we need to run our bodies and build their bones.

They convert to calcitriol (1, 25[OH]2D3)

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Vitamin D2 is found in plant-based foods and fortified products like plant milks, while vitamin D3 is synthesized in the skin through sun exposure and is found in animal products like salmon, liver, and eggs. Vitamin D2 may be less effective at raising and maintaining blood levels compared to D3. 

Minor chemical differences.

Over my head:

secosteroids; Ergo- chemistry prefix, ergosterol found in plants and fungi [s precursor to Vitamin D2]; sigma; pericyclic; cycloaddition; Diels-Alder; diene reacts with a dienophile (an alkene or alkyne); Deuterium (D]; 23(OH)D3;