What are water-soluble vitamins, and how are they typically excreted?

• A. Vitamins A, D, E, and K; excreted in urine.
• B. B-complex vitamins and vitamin C; excreted in urine.
• C. Vitamin B12; excreted in bile.
• D. Vitamin K; excreted in feces.

Answer: (B)

Water-soluble vitamins include the B-complex group and vitamin C, and they are typically excreted in urine. These vitamins dissolve in water, travel freely in the bloodstream, and aren’t stored in large amounts in the body's tissues. When you take more than the body needs, the kidneys filter out the excess and send it out in urine. That’s why regular intake via diet is important for these vitamins.

In contrast, fat-soluble vitamins A, D, E, and K are stored in liver and fat tissues and are usually eliminated through bile into feces rather than in urine. Vitamin B12 is technically water-soluble but can be stored in substantial amounts in the liver, so its excretion pattern isn’t as rapidly urine-driven as the others. So, the water-soluble group that’s commonly excreted in urine is the B-complex vitamins plus vitamin C.