Are vit d supplements effective at all? does it replace sun exposure?

We all need some D: We need supplements if we do not get enough from foods, drinks, or other supplements. Long term vitamin D deficiency in adults can lead to osteomalacia (bone softening) and osteoporosis (bone density loss, with easy fracturing). Other symptoms of a deficiency of vitamin D are muscle pains, muscle weakness, and aches in the bones. Prolonged vitamin D deficiency in children causes bone deformities.