Dear Science,

After suffering one too many colds over our prolonged Seattle winter, I started taking a daily multivitamin. I feel the same, but my pee is much yellower these days. Is my body actually absorbing any vitamins or am I just pissing my money away?

Frugally Health Conscious

Science must first commend you on your rational, appropriately skeptical question. While walking through the vitamin aisle of the local grocery store, the sheer volume of magical powers—in the sense that they are unproven and probably unprovable—ascribed to vitamins is disheartening. In comparison, a daily multivitamin is downright grounded—rational in a delightful way. You, madam or sir, are apparently not an easily duped fool.

Vitamins are small organic molecules (as in, made predominantly of carbon atoms linked together in complex chains). Depending upon the exact shape and structure of the vitamin molecule, the vitamin prefers being in water (water-soluble vitamins) or fat (fat-soluble vitamins). Human bodies cannot (in general) store water-soluble vitamins. This plays both ways: Each of us needs a steady supply of water- soluble vitamins to function at optimum levels. If you consume too much of a water-soluble vitamin, you (indeed) pee it out. Hence the inherent ridiculousness of (absurdly expensive) massive-dose vitamin C pills—the water-soluble vitamin C mostly ends up making your toilet bowl smell like citrus.

Fat-soluble vitamins, in contrast, can be stored in your body's fat. Vitamins D, A, K, and E are the major fat-soluble vitamins. The human body can use these stores to patch over times of deficiency. The ability to store up means one can overdose to the point of toxicity with fat-soluble vitamins. Too much vitamin D can make calcium levels in the blood skyrocket to dangerous levels. Vitamin A overdoses can cause an exciting mix of symptoms: insomnia, irritability, hair loss, and muscle aches, all leading up to fluid buildup around the brain. Too much vitamin K can kill liver cells. Vitamin E alone is without any known toxic dose; studies over the years have in fact shown the overall health benefits of high vitamin E levels. (The amounts in a daily multivitamin are far too low to cause problems with any of these vitamins.)

In short: You're undoubtedly peeing out a whole bunch of the expensive water-soluble vitamins in your daily multivitamin. But the fat-soluble vitamins in the pill are being stored in your body for the apocalypse. (Thanks, body!) For the few water- soluble vitamins your diet isn't providing, the daily multivitamin is probably helping quite a bit. Overall, it's probably a good idea for most of us to take a multivitamin—unless you are the only American who actually eats the needed amounts of fruits and vegetables each day.

Supplementally Yours,


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