Retinoic acid is a noun for a derivative of vitamin A. That is the definition and it's also a sentence for retinoic.
The more polyunsaturated fats you eat, the more vitamin E you will get.
You need your vitamin c
I eat a vitamin every day before school.
Yes, the word "Vitamin" should be capitalized at the beginning of a sentence.
He supplements his income by working nights. (verb) They take vitamin supplements. (noun) Pregnant and nursing mothers should usually take an iodine supplement. (noun)
Vitamin A.
Vitamin A
No, the word "vitamin" should not be capitalized unless it is the first word in a sentence or part of a proper noun (e.g. Vitamin C).
Vitamin toxicity can be prevented by minimizing the use of vitamin supplements.
She takes a daily multivitamin to ensure she is getting all the necessary vitamins and minerals for her health.
You can, but traditionally coordinating conjunctions (such as and, but, or) are not used to start a sentence. You might consider using "alternatively" instead. For more synonyms of "or" consult a thesaurus or dictionary.