Complex sentence: Clothing reduces the amount of skin exposed to UVB and natural Vitamin D sythesis, the assesment of whether this poses a lifestyle-related health risk depends on the definition of deficiency that is used.
Split into simpler sentences: Clothing reduces the amount of skin exposed to UVB and natural Vitamin D sythesis. The assesment of whether this poses a lifestyle-related health risk depends on the definition of deficiency that is used.