This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
What is food?
The Merriam-Webster Dictionary entry says “Something that nourishes, sustains, or supplies.”
How beautiful. That statement captures much of the emotion and feeling surrounding food, yet it’s only part of the full definition.
On supporting science journalism
If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
So where does food begin?
As with most big questions, it depends who you ask. Let’s start down the reductive reasoning road: a young child might say food starts when a parent sets a plate in front of them. A chef might use her well-honed knives and skills to carefully craft food from hand-selected farm-fresh ingredients. The farmer, in turn, knows food consists of the animals and crops he raises.
An ecologist would stress interconnectedness, webs and cycles that show the flow of food nutrients and energy through different populations. Biologists break foods down further, stripping starches and proteins down to simple sugars and amino acids. Chemists (like me!) take the next leap, deconstructing those food components into energy released from the making and breaking of atomic bonds (since we’re already at the atomic level, we should mention that lots of folks – biochemists, engineers, organic chemists, materials scientists – try to build these food molecules from simpler stuff).
Further along, astronomers and physicists look to the sun, the giant ball of fusion energy constantly sending photons, tiny packets of light, in our direction. Plants and microorganisms use these photons to drive food formation. Could our nourishment have roots beyond the stars? Maybe; science traditionally leaves these questions to philosophers and religious authorities.
Let’s come back down to Earth, where I’ll stake my claim for this Food Matters group venture. For me, food begins when molecules you can’t eat – nitrogen gas, carbon dioxide gas, certain salts and minerals – turn into something you could eat. To achieve this feat, one must drill down to the level of enzymes, biology’s tiny chemistry factories.
The inner workings of just one enzyme could easily fill a series of posts, so I won’t dive too deeply here. By greatly speeding up certain reactions, enzymes turn metabolically inert substances into the starting materials for sugars and proteins. Their “fuel” comes from many places: heat and light from the sun, electrons flowing from metals, other reactions, and small differences in pH or concentration. Enzymatic reactions, which happen billions of times a day all around us, go largely unnoticed. Yet they make everything you put in your belly, from apples to zucchini.
Once you’ve seen food at the atomic scale, it’s tough to go back. Savory steaks? Muscle tissue, seared to perfection. Yogurt? An active stew of bacteria pre-digesting milk products. Nuts? Full of monounsaturated fats, which have an olefinic “kink” in their chains, meaning they can’t pack together as well as saturated fats. Not to mention all those vitamins, which have complex structures rivaling pharmaceutical molecules.
Remember that dictionary definition at the top? Here’s the rest: “Food:Material consisting essentially of protein, carbohydrates, and fat used in the body of an organism to sustain growth, repair, and vital processes and to furnish energy.Inorganic substances absorbed by plants in gaseous form or water solution.”
Let’s explore this delicious molecular playground together. I hope to convince you that food begins and ends with chemistry.