The study of grasses: A key component of the human diet

In All, Food Products, General, Nutrition by Emily Frankman


Article by Emily Frankman, PhD Candidate, Department of Biochemistry and Molecular Biology, Michigan State University

In the world of small talk, we’re all familiar with that unavoidable question from a new acquaintance: “So what do you do?”

My response for the past four years has been, “I’m a graduate student in biochemistry.” When I mention biochemistry, I’m often met with a surprised or impressed look, and am asked, “What exactly do you study?”

I study grasses. Specifically, I study grass cell walls and how they are constructed in the plant. When I reply with this answer, people often seem puzzled. With biochemistry, they probably imagined something really exciting and important. Probably something related to human medicine. So why grass?

What a lot of people don’t realize is that humans eat grass. But to be clear, this grass isn’t from your lawn. The grasses I study are known as cereals, which belong to the family Poaceae. Members of this group of grasses include corn, wheat, rice, oats, and barley. Cereal grasses are a major food source in the human diet, either through direct consumption or as feedstock for the meat we eat. Imagine going a whole day without eating one of these cereal grains (it would be difficult!). In terms of economic value, corn alone had a $49 billion crop value in 2013.

When thinking of grass, most of us probably first picture the green parts: the stems and leaves. All grasses certainly have these components, but the part of cereal grasses we eat is the seed, or grain. The composition of the grain is very different from that of the stem and leaf tissues. While the stems don’t provide much nutritional value to humans, the grain contains a lot of essential and nutritious components, such as proteins and carbohydrates.

Remember, the grain is the plant’s seed, and it represents the plant’s efforts at reproduction. The plant sends many macronutrients to the seed because it will eventually detach, survive off of the nutrients it has been given, and become its own plant. Humans benefit from collecting and consuming the macronutrients that the plant has cleverly packaged into seeds.

The grains from cereal grasses are actually seeds packed full of nutrients.

The grains from cereal grasses are actually seeds packed full of nutrients.

The part of grasses that I specifically study is the grass cell wall. The grass cell wall is very important to human diet in the form of dietary fibers. A significant portion of plants is made up of the cell wall, which has several components. These components are varied in different tissues of the plant.

For example, the stem has a high amount of cellulose and lignin, components of the cell wall that humans are unable to digest. Cellulose and lignin are also found in the grains we eat, but typically in lower amounts. These two cell wall components are known as insoluble fibers, which contribute to the dietary fiber humans require. We also get soluble fibers from eating cereal grains. Soluble fibers are components that dissolve in water. Some soluble fibers include arabinoxylans and mixed linkage glucans, chain-like structures in the cell wall that make up a large portion of the grain.

Having both soluble and insoluble fibers in our diet is very important. Dietary fibers promote a healthy digestive system, make us feel fuller longer, and can reduce the risk of colon cancer. A large portion of our daily fiber intake can be met by eating cereal grains, especially of the “whole grain” variety. A cup of corn alone provides almost half of your daily value in dietary fiber!

The FDA has recently updated the nutrition facts label to show dietary fibers alongside the added sugars in packaged foods. The reason this is important in the context of added sugars is that having more added sugars in your food will make it difficult to stay within your daily caloric intake and still get enough dietary fiber. One of the benefits of having dietary fiber in your diet is feeling fuller for longer, which can help people maintain a healthy weight.

Grasses may seem like a boring thing to spend your life studying, but they are a critical component of our food supply and provide us with so many nutritional benefits. The grains we eat from them – the grasses’ seeds – are literally feeding the world. So with the holidays approaching, you’re bound to run into some small talk with relatives and new friends. And while it can sometimes be repetitive and exhausting, think of the many things we can learn from one another solely from the question, “So what do you do?”