Vitamin A deficiency leads to xerophthalmia, characterized by eye dryness, night blindness, and potential total blindness without treatment. Xerophthalmia, meaning "dry eyes", can cause corneal ulceration and blindness. Early signs of deficiency include difficulty seeing in low light and a higher risk of infections. Vitamin A, crucial for eyesight and immune support, is found in green leafy vegetables, orange and yellow vegetables, fruits, dairy, liver, and fish. Conversely, Vitamin K, vital for blood clotting and bone health, is sourced from green vegetables for K1 and fermented foods for K2. Pellagra, resulting from Niacin (Vitamin B3) deficiency, presents as dementia, diarrhea, and dermatitis, and can be fatal if untreated.