***This excerpt is from an advance uncorrected proof*** Copyright © 2015 Catherine Price High Seas and Hi-C [W]hat is the function of these vitamines? If fats and carbohydates provide the fuel, and proteins the material for tissue supply, and mineral salts are needed for bone construction, etc., just what do the vitamines supply? We do not know. -- Benjamin Harrow, The Vitamines: Essential Food Factors, 1922 The first time I saw a vitamin in pure form--as opposed to just gulping one down in a pill--was in Parsippany, New Jersey. It was a drizzly November day, and I was visiting the Nutrition Innovation Center, a product-?development facility run by the world''s largest synthetic vitamin producer, the Dutch company DSM. Companies come to the center to brainstorm and create new products, harnessing the expertise of DSM''s chemists and flavor technicians to add vitamins and other so-called functional ingredients to their foods. But I hadn''t come to develop a new fortified beverage or cereal or snack bar. My goal was more basic: after more than three decades of eating and taking vitamins, I had come to the center to learn what vitamins actually are. My host for the day was DSM''s senior director of global technical marketing, a French-?born pharmacist and PhD named Jean-?Claude Tritsch, who had ear-?length graying hair and wore a pink V-neck sweater.

We were in the room where product concepts are shared and sampled with food and supplement companies, and Tritsch was explaining the basics of vitamins from behind a wet bar as I sat perched on a high stool at a granite countertop, a selection of product prototypes arranged in front of me. When we hear the word "vitamin," many of us immediately think of pills; we also tend to mistakenly apply the term to all dietary supplements, and often lump vitamins and minerals together. But as Tritsch explained, there are actually only thirteen human vitamins, all of which are organic compounds that occur naturally in food. Four are fat-?soluble, meaning they dissolve in fat and need fat to be absorbed: A (retinol), D (cholecalciferol), E (tocopherol), and K (phylloquinone). The other nine are water-?soluble: C (ascorbic acid) and the eight substances grouped together in what''s called the B complex-- B1 (thiamin), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), B7 (biotin, also sometimes referred to as vitamin H), B9 (folate/folic acid), and B12 (cobalamin). Sometimes choline is counted as a fourteenth vitamin, but usually the roster ends at thirteen. (Some vitamins come in more than one chemical form-- the parentheticals refer to the most common or the most relevant.) Unlike the macronutrients (fat, protein, and carbohydrate), vitamins are not burned as fuel; instead, their primary role is to facilitate chemical reactions in our bodies that keep us alive.

Vitamins, Tritsch told me, are thus considered essential micronutrients-- essential because our bodies require them but can''t make sufficient quantities, which means we need to get them from outside sources, and micro because we only need them in really small amounts, typically fewer than 100 milligrams a day. Indeed, we need vitamins in amounts so tiny that it''s difficult to visualize them, let alone to believe that our lives depend on them. The amount of folic acid that pregnant women are told to take to prevent devastating neurological defects in their babies is 240 micrograms a day, less than the weight of two grains of Morton salt. The Recommended Dietary Allowance for vitamin D, without which you won''t be able to properly absorb calcium and your bones will soften, is 15 micrograms (600 IU), one-?sixteenth of that for folic acid. And the RDA for B12, a vitamin whose deficiency can cause depression, delusions, memory loss, incontinence, nerve damage, and in extreme cases life-?threatening anemia, is smaller still, just 2.4 micrograms--0.0000024 grams. That''s 1/ 100th of the weight of the requirement for folic acid, the equivalent of 1/ 67th of one grain of salt.

Searching for a way to make those tiny numbers tangible, Tritsch let me taste and smell several samples of pure vitamins that were kept on hand at the lab. Vitamin C was a talc-?like white powder, tart like a Super Lemon candy and very irritating, I discovered with the help of a paper cut, if rubbed into an open wound. Thiamin was bitter and white. Powdered riboflavin was the color of butternut squash. Folic acid was yellow and tasted chalky. A and D were clear, sticky, meltable crystals, so concentrated and unstable that they''re usually dissolved in oil. E was a tasteless, viscous clear fluid. Vitamin B12 was bright pink.

By the time I left the Innovation Center, I''d seen diagrams of vitamins'' chemical structures and magnified photographs of individual molecules, colorful crystals that sparkled in the light. But even after I''d touched them, tasted them, and smelled them, I still couldn''t wrap my head around what I was experiencing. It seemed somehow impossible that these odorless, unassuming substances could be essential for keeping me--and every one of us--alive. The problem, I realized, was that I still didn''t understand what vitamins do in our bodies--which is a necessary concept to grasp if you want to understand why a deficiency could kill you. So I decided to look for an explanation in the vitamin I thought I knew the best: vitamin C. Most people know that if you don''t have enough vitamin C, you''ll develop a vitamin deficiency disease called scurvy, and you have probably heard tales of sailors on long sea voyages whose teeth fell out as a result. But having loose teeth, while certainly unpleasant, doesn''t sound life-threatening. And besides, scurvy can be cured by drinking orange juice.

How serious could it really be? Really serious, it turns out. Far from just affecting their gums, scurvy killed more than two million sailors between Columbus''s 1492 transatlantic voyage and the rise of steam engines in the mid-?nineteenth century. It was such a problem that ship owners and governments counted on a 50 percent death rate from scurvy for their sailors on any major voya≥ according to historian Stephen Bown, scurvy was responsible for more deaths at sea than storms, shipwrecks, combat, and all other diseases combined. Scurvy starts with lethargy so intense that people once believed laziness was a cause, rather than a symptom, of the disease. Your body feels weak. Your joints ache. Your arms and legs swell, and your skin bruises at the slightest touch. As the disease progresses, your gums become spongy and your breath fetid; your teeth loosen and internal hemorrhaging makes splotches on your skin.

Old wounds open; mucous membranes bleed. Left untreated, you will die, likely as the result of a sudden hemorrhage near your heart or brain. Bown quotes a survival story written by an unknown surgeon on a sixteenth-?century English voyage that illustrates scurvy''s horror. "It rotted all my gums, which gave out a black and putrid blood," he wrote. "My thighs and lower legs were black and gangrenous, and I was forced to use my knife each day to cut into the flesh in order to release this black and foul blood. I also used my knife on my gums, which were livid and growing over my teeth. When I had cut away this dead flesh and caused much black blood to flow, I rinsed my mouth and teeth with my urine, rubbing them very hard. And the unfortunate thing was that I could not eat, desiring more to swallow than to chew.

Many of our people died of it every day, and we saw bodies thrown into the sea constantly, three or four at a time." Scurvy affected many of the explorers we learned about in grade school--Vasco da Gama lost his brother to it; Ferdinand Magellan watched it kill many of his men, who had been reduced, he wrote, to existing on "old biscuit reduced to powder, and full of grubs, and stinking from the dirt which the rats had made on it when eating the good biscuit." Scurvy killed so many men on the 1740-1744 voyage commanded by a British captain named George Anson that it is considered one of history''s worst medical disasters at sea. When reading about such experiences, it''s difficult not to want to travel back in time, grab these men by the shoulders, and beg them to eat some lemons. The idea that certain foods can cure scurvy wouldn''t even have been a new idea--in 1535, French explorer Jacques Cartier reported that after his ships had become frozen in the St. Lawrence River, his men were saved from scurvy by a special tea, prepared by the local Native Americans from the bark and leaves of a particular tree. In the 1500s and 1600s, several ships'' captains suggested that there might be a connection between produce and scurvy. In 1734, a Dutch physician named Johannes Bachstrom came up with the term "antiscorbutic"--against scurvy-- and used it to describe fresh vegetables.

Even Anson--captain of the aforementioned disastrous voyage--made a point of loading up on oranges whenever possible, and his chaplain, Richard Walter, described certain vegetables as being "esteemed to be particularly adapted to the cure of those scorbutic disorders which are contracted by salt diet and long voyages." But while many mariners recognized that there was a connection between sailors'' diets and their susceptibility, no one knew the true cause of scurvy, or what made certain foods antiscorbutic. Today, scientists understand the connection, and it has to do with what vitamins are actually doing in our bodies. Despite their chemical differences, all vitamins play crucial roles in our metabolism, a term that refers to the series of chemical reactions that occur in our cells. Though we are rarely aware of these metaboli.