Two years ago, I began a series of posts based on Randall Munroe’s book, What If? The What If? book and website are described as “serious scientific answers to absurd hypothetical questions.” However, there were some questions that were too absurd even for Randall. He printed a couple dozen of them in his book without answering them, just for the humor value, but I decided I would answer them. Thus, the What If? Rejects series was born.
Unfortunately, my life went nuts while I was finishing my doctorate, and my blogging mostly fell by the wayside for the past year, leaving the series half finished. But now, I’m bringing it back!
When last we met, I was in the middle of answering “Weird (and Worrying) Questions from the What If? Inbox #6”, Question 1: What is the total nutritional value (calories, fat, vitamins, minerals, etc.) of the average human body?
I calculated the calorie count of the average human body in this post: 560 servings of 200 calories each. In my second post, I calculated the macronutrients: fats, carbs, and protein, including sugar and cholesterol. Now, it’s time for the micronutrients: the vitamins and minerals.
The FDA only requires vitamin A, vitamin C, calcium, iron, and sodium quantities to be listed in products’ nutrition facts labels, but lets do all of them. There are 13 essential vitamins and 15 essential minerals that are needed by the human body, and calculating how much of them can be found in the body is actually quite a bit easier than figuring out carbs, proteins, and fats.
You see, each vitamin and mineral has something called a biological half-life. This is a little like a radioactive half-life, but instead of the time it takes for half of a substance to decay, it’s the time it takes for one half of a particular chemical to be eliminated from the body. So in order to find out how much of a vitamin or mineral is in a healthy human body, you just take its Reference Dietary Intake (formerly Recommended Daily Allowance), multiply by its biological half-life, multiply by 1.44 because logarithms, and you’re done.
Finding out the Daily Value per serving is even easier. The biological half life times 1.44 tells you the number of Daily Values in the body directly. Then just divide by the number of servings. For many vitamins, the number is zero: they get metabolized into other chemicals in the body in a matter of hours. Minerals, on the other hand, can stick around for a long time. You can look up the numbers for yourself, but here’s the end result:
Vitamin A: 64% Vitamin B1: 3% Vitamin B2: 0%
Vitamin B3: 0% Vitamin B5: 0% Vitamin B6: 0%
Vitamin B7: 0% Vitamin B9: 3% Vitamin B12: 2%
Vitamin C: 4% Vitamin D: 4% Vitamin E: 1%
Vitamin K: 0%
Sodium: 5% Magnesium: 11% Phosphorus: 5%
Chlorine: 3% Calcium: 4,629% Potassium: 4%
Chromium: 158% Manganese: 10% Iron: 469%
Cobalt: 1% Copper: 5% Zinc: 72%
Selenium: 26% Molybdenum: 1% Iodine: 21%
Note that the average of the human body (as opposed to particular tissues) is not particularly edible because you are liable to overdose on iron.