Plants-based foods are a major part of human nutrition and health. Human nutrients can be put into two main categories: macronutrients and micronutrients. The key to maintaining good health is to balance macronutrients, and to have a good, steady supply of micronutrients. Information about the amount of nutrients in a food is usually easy to find on processed, labeled, foods in the grocery store. However, it is usually missing from bulk and fresh foods like grains, vegetables, and fruits.
Human nutrition is based on our need to get our energy from food and to get enough minerals and vitamins to function. We get our main energy (i.e. calories) from macronutrients in the diet, mainly carbohydrates and fats. We can get energy from protein too, but it’s better for us to use this as a source of amino acids to make protein in our bodies. Also, there are different types of carbohydrates, fats, and protein that can be better or worse for you, and different crops and different types of macronutrients.
Carbohydrates: Plants make three main types of carbohydrates: sugars, starches, and fibers. Our bodies’ metabolism runs by processing sugar, so we need a steady amount in our bodies. The main crops that produce sugars are sugarcane, sugar beets, and corn. These crops are usually processed to pull out the sugar from the plant material. While sugar is important for energy and nutrition, we know that too much per serving is a bad thing. Too much sugar in our diets can lead to blood sugar spikes that, over time, can lead to diabetes. Therefore it’s good to include other forms of carbohydrates in the diet: starch. Starches are made up of long chains of sugars. This means that our bodies have to work to break down the starches before we can absorb them for energy. This ‘work’ is a good thing! The longer the body works at it, the lower the sugar spike in the blood. Cereal crops such as rice, wheat, corn, oats, barley, sorghum, millet and the legume crops green peas and cowpea are all good sources of starch. Plantains are a fruit with a good starch. Some root and tuber crops pack their starch below the ground: potato, sweet potato, yams, cassava, and parsnips.
Fibers: Plants will also turn carbohydrates into fibers during their metabolic processes. But, the human body isn’t that good at digesting fiber and absorbing the underlying carbohydrates for energy. Instead, fiber is important to gut health. While we don’t use them for energy, the microbes in our gut do, and they also need to be kept healthy! Also, some fibers are broken down by microbes, and only then can our body use the carbohydrate for energy. Fibers are found in vegetables, fruits, and whole grain cereals. There are so many different kinds, and they are all important in the diet, and so the best thing is to mix it up with our diets.
Fats: Because too much carbohydrate is bad, it’s important to balance our much needed energy with fat. This fat can come from the plant itself, or can be processed into oils for cooking. The most important crops for cooking oils are peanut, soybean, canola, sunflower, and coconut. Also, like carbohydrates, the type of fat can widely vary for different crops. For example, tree nuts, peanuts, canola, and avocado are good sources of unsaturated fats (the “better-for-you” fats).
Protein: Dietary protein is our major source of amino acids that we need to maintain good health. While we normally think of animal products for protein, plants make protein, too. But, some plants are considered to have ‘incomplete’ protein because they can be low in certain types of amino acids. For example, some grains can be low in lysine, and some legumes low in methionine. This means that balancing plant protein from different crops is important. Good sources of plant protein are beans, lentils, soybeans, green peas, cowpeas, quinoa and peanuts. Other cereal crops also have proteins in their seeds, but these are more important for baking quality than human nutrition. (To learn more about dry beans, visit our International Year of Pulses 2016 page).
Micronutrients: Unlike the macronutrients that provide us with energy, we use micronutrients get our bodies to function normally. The two types of micronutrients are vitamins and minerals. For both, there is a certain amount that is required for us to be in good health, and so it’s less about balancing the types of micronutrients, and more about making sure we have enough. While fruits and vegetables are excellent sources of both vitamins and minerals, whole grain cereals, legumes, and roots and tubers are also good. For example, potato is high in potassium, legumes are generally high in iron, and processed vegetable oils (described above) are usually high in Vitamin E.
Balance is the most important part of nutrition, as overdoing one nutrient is usually at the expense of another. Different plants produce different types of carbohydrates, fats, and protein, vitamins, and minerals. This is why including many different types of food crops in the diet is great for health.
Answered by Adam Heuberger, Colorado State University
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