Nicotinic acids, also known as niacin or Vitamin B3, play an essential role in maintaining healthy skin, nerves, and digestion. However, like any other word, niacin also has its antonyms. One such antonym is 'deficiency,' which refers to the lack of niacin in one's diet. Another antonym is 'toxicity,' which indicates excessive amounts of niacin in the body, causing adverse effects on health. Additionally, 'insufficiency' could be an antonym for niacin, which means inadequate amounts of niacin in the body. Lastly, 'intolerance' could also be an antonym for niacin, which refers to the inability to absorb niacin adequately. Thus, understanding these antonyms helps us appreciate the value of niacin in our daily diet.