See Grain Science for more information regarding the parts of a grain.
Porridge is a universal nutritious food.
Grains are the global staple food because they offer a reliable source of energy. They can be stored for long periods of time, or processed into other forms. Different grains have different quantities of carbohydrates, protein, and vitamins.
When we say grains are the main source of energy, we actually mean carbohydrates. Rice, corn, wheat, potatoes, sugar, and cassava are the staple food sources that comprise up to 90% of the diet of some tropical populations, less than 10% of the Eskimos’ energy, and 45-65% of Americans’ daily average intake. Carbohydrates are made up of two component parts: sugar and fiber.
Grains are fruits that come from grass plants. Plants photosynthesize and convert water, carbon dioxide, and sunlight into sugar. They store sugar as starches in grain fruits. Humans break down starches into glucose, a sugar fuel that runs through our blood. Fiber keeps us full. It cannot be digested, so its presence makes our bodies work for their nutrition, as well as keeping the digestive system running efficiently – it is a bit like a sponge that gets run through your intestines. Sometimes the body can extract amino acids and minerals from fiber.
In the mouth:
1.Salivary amylase, an enzyme in the mouth, begins breaking down what has been eaten. Swallow!
Proceed to the stomach:
2. Fiber hangs out in the stomach and provides satiety – it makes you full. All sugars are broken down to make glucose.
3. Pancreatic amylase (an enzyme in your pancreas) and specific disaccharide enzymes (maltase, sucrase, lactase) continue the breakdown of sugars through glycolysis. Glycolysis is a process where enzymes break down glucose into specific molecules that can be put back together again to make ATP, the energy currency that your body runs on. Glucose is an unrefined fuel, glycolysis and the Krebs cycle are part of the refining process that convert it into a usable form of energy on a micro level, where your cells and cell parts are putting together strings of proteins that get used for various functions.
4. The deconstructed components from glycolysis are then carried by vitamins acting as “cofactors,” or catalysts, into the Citric Acid, or Krebs Cycle. The Krebs cycle takes carbons, hydrogen atoms, and the vitamins acting as catalysing agents to form essential 5 carbon sugars, glucose, and NADPH and ATP (energy!). Fats cannot be fully oxidized without the oxygen from carbohydrates (respectively made of carbon, hydrogen, and oxygen atoms). If your body is completely starved of carbohydrates it will go into ketosis, because fats and proteins cannot be broken down into glucose. Your body runs on glucose! Your brain needs 50-100g CHOs/day to prevent the body from breaking down its proteins to try and make glucose.
In the large intestine:
5. The bacteria in your microbiome breaks down fiber. A diet high in fiber can lower cholesterol because fiber binds to bile, which carries the lipoproteins of cholesterol. If you have heard of HDL (high density lipoprotein) or LDL (low density lipoprotein) in context to cholesterol, know that they travel around in bile. Fiber also binds to minerals like calcium and zinc so that they can be digested easily. Sometimes fiber can be dissolved into short fatty acid chains, carbon dioxide, water, and methane components, all of which your body can use for different reactions.
6. Excess glucose gets stored as glycogen in your liver. When you are not eating, your liver releases glycogen to keep your body at a homeostatic level of blood glucose. Insulin removes excess glucose from the bloodstream, while Glucagon and Epinephrine release glucose through a process called glycogenolysis. A food’s glycemic index refers to the speed with which the body absorbs and uses a food’s glucose, and how long it takes the body after eating the food to return to normal blood sugar levels. A low glycemic index is desirable for regular consumption, because it acts slowly, so you avoid a crash or comedown. Exceptions would be for diabetics, who cannot regulate their blood sugar levels and need spikes of blood sugar to maintain a relative homeostasis, or an athlete looking for a quick source of energy – a marathon runner eating a goo packet of pure sugar to give them a needed boost. When your body consumes more carbohydrates than it needs to balance out its activities – breathing, thinking, bodily functions, exercise – excess glycogen is converted to fat for long term storage.
Proteins are made up of amino acids. Amino acids make up a lot of structures in the body, including: genes, DNA, RNA, and enzymes, which carry out metabolism and other reactions in the body. Protein also provides structure. It makes up the cytoskeleton of cells, connective tissues in the body, your hair, and: wait for it: provide force that contracts muscles (why your body builder friend brings his protein powder to school with him). Proteins also act as transport channels on cell membranes, allowing for processes like the sodium ion pump crucial for making ATP. Antibodies, the receptors that signal to white blood cells in the immune system which invading viruses and bacterias to attack, are made of protein! Protein is very important, and you should be eating it every day. Luckily, a lot of whole grains have a high amount of protein! A typical serving of protein according to the American Diabetes Association is 7g. Thus, grains are not “protein foods,” but do contain significant protein content! A typical serving (45g uncooked) of grain contains between 2.5-7g of protein. Whole grains (those with the bran attached) contain more protein.
As mentioned, vitamins carry out reactions in your body. If you are deficient in a vitamin, you can get very sick and die, because your body can’t carry out the reactions that it needs to. Grains are notable for carrying lots of B Vitamins: a complex of 12 different vitamins, denominated by numbers B1-B12, except folate, which just goes by folate. In history, certain cuisines have combatted vitamin deficiencies through culinary adaptation! This was not always conscious but rather instinctual. For example, when British sailors started getting scurvy (a Vitamin C deficiency that causes painful gum bleeding) they noticed that symptoms disappeared after eating citrus. Thus they stored lots of fruits on their boats for long journeys, and acquired the name “Limeys.”
2 Tales of Grains:
- The Japanese Pickle. The Japanese began refining whole grain rice into white rice. When you refine a grain, you remove the bran and endosperm. These parts are where the vitamins live! Thus, the Japanese started getting a disease called beri-bero, which happens when one is deficient in Thiamine, or Vitamin B1. Beriberi can lead to heart failure, muscle paralysis, and damage. In less extreme cases it makes one very fatigued, confused, and lack of coordination. However, people noticed that the symptoms went away when they ate fermented pickled vegetables. The fermentation process increases thiamine content. Japanese cuisine then evolved to create nutritionally balanced dishes that paired processed white rice with pickles, so that they would receive sufficient thiamine.
- Corn and Pellagra in the Americas. Southern prisoners and sharecroppers who were fed a diet of cornbread (refined corn flour and lard), molasses (sugar), and “fat back” (more lard) started getting very sick. Their symptoms: Diarrhea, Dermatitis, Dementia, and Death. They had a disease called Pellagra because they were deficient in vitamin B3, Niacin. The millers who made the corn flour did so by removing the bran of the grain, where, again, all of the vitamin nutrition was located. Thus, the poor southerner’s diet was not nutritionally sufficient. A US Public Health Official named Joseph Goldberger came to study the phenomenon in 1914 and was one of the pioneering scientists to write about diseases of nutritional deficiencies. He also noted another backstory of a culture geographically nearby that subsisted mainly on corn: los indígenos, the Mexicans. They ate lots of tortillas made from pressed corn flour called masa. However, their culture had developed a process called “nixtimalization” to counteract vitamin deficiency, wherein the cooks would soak the corn in lime water before pressing it into flour. The lime reacted chemically to the vitamins and released niacin into the water, so that when it was formed into tortillas, the vitamin was still bioavailable. Goldberger’s work led to the now standard US practice of enriching processed flours, or adding lost vitamins back into the final product.
TLDR: whole grains are great! You can’t live on grains alone (eat your veggies! Vegans eat your Vitamin B12 supplements & everyone else, drink milk.), but they’ll get you most of the way to a balanced diet, which is why they are the base of cuisines all over the world.