Part 1: Carbs, Protein, and Fat
Based on the book: "The Science of Nutrition" by Rhiannon Lambert
Did you know you can get most of your vitamins and minerals from plants. Plant foods come in various colors and shades, and their color is linked to the nutrients they contain. For instance, orange often indicates the presence of vitamin A; purples indicate antioxidants; greens contain vitamin K and iron; and red vegetables contain lots of vitamin C. So a colorful diet will give you a well-varied nutrient intake. Let’s take a look at our 3 macronutrients starting with carbohydrates! What are carbohydrates? Carbohydrates are the body’s greatest energy source. They provide the body with glucose to use for energy, which can also be stored (as glycogen) for future use. Carbs also play a valuable role in gut health, by providing useful fiber to the digestive tract. Glucose is the preferred energy source for muscles during strenuous exercise. It is only when the body’s glucose supply is depleted that it turns to fat for energy. The body also requires glucose to fuel multiple unconscious biological processes. Glucose is essential fuel for the brain, aiding in concentration. Carbohydrates play an important role in generating the brain’s serotonin supply. This mood-regulating hormone is made with tryptophan, an amino acid obtained through protein in the diet. Carbs help convert tryptophan into serotonin, so eating carbs may help enhance mood. This might explain why carbs and sweet foods are often treated as comfort foods. In the small intestine, the less starchy complex carbs are broken down into simple carbs. All non-glucose monosaccharides are converted into glucose in the liver, which is released into the bloodstream. It is either used immediately or converted into glycogen (a polysaccharide of glucose), which is stored in the liver and muscles for later use. Fiber refers to any complex carbohydrates that cannot be broken down by the digestive enzymes in the small intestine. This fibrous matter moves into the large intestine, where it helps produce highly useful short-chain fatty acids and nourishes the lining of the gut. Single molecule Monosaccharides "Mono" means "one"; "saccharide" means "sugar." These are carbs in their most basic form. Glucose: grains, pasta, Fructose: fruit, honey, and Galactose: dairy. Two molecules Disaccharides: When two monosaccharides bond chemically, they form a disaccharide. Lactose: dairy, Sucrose: sugar beet, cane sugar, and Maltose: molasses, beer. Multiple molecules Polysaccharide: Carbs can be made up of hundreds, even thousands, of monosaccharides. These are called complex carbs which include many vegetables, beans, lentils, and whole grains. There is no such thing as an inherently good or bad carb. All foods have a place—it’s about finding the right balance for your own body. There’s a strong case for reducing refined carbs, like white bread, and opting for complex carbs, like whole grains, which release energy slowly. While refined carbs are great for providing energy quickly, they usually lack essential nutrients. What is protein? The macronutrient protein is a major player in the diet. It is the body’s building block, used to form and repair muscles, skin, hair, and nails, for instance. Protein also enables many of the body’s vital metabolic functions. Proteins are made up of amino acids. The body can produce many of the amino acids it needs to make peptides and proteins, but nine of them, known as essential amino acids, must be sourced from the diet. Because the body doesn’t store proteins in the same way it does other macronutrients, it needs to consume proteins every day. Food sources containing all nine essential amino acids in sufficient quantities are known as complete proteins. They are found in animal products and a few plant sources. Incomplete proteins are plant-based sources of protein that don’t contain all nine essential amino acids, or don’t have sufficient quantities of them to meet the body’s daily requirements. Although “incomplete,” they are no less valuable than complete proteins as protein needs are met across the whole day, not just at each individual meal. Vegans and vegetarians are advised to eat a wide variety of protein-rich and fortified foods to ensure they consume all nine of the essential amino acids each day from both complete and incomplete sources. In the US, adults are advised to consume 0.8g protein per kg (2lb) of bodyweight per day. (Particularly active people should increase this intake to 1g.) Based on average weights and activity levels, daily intake should be 56g for men and 46g for women. That’s about two palm-size portions of meat, fish, tofu, nuts, or beans. As we grow older, our bodies become less efficient at using protein. Increasing protein intake makes it more likely we’ll meet daily requirements. What is fat? Fat is a macronutrient found in many food sources. Consuming fats is vital to the body’s function, including processes such as brain activity, hormone production, and the body’s absorption of other nutrients from the diet. Monounsaturated fatty acids (MUFAs) are typically liquid at room temperature and are fairly stable for cooking purposes. The most common MUFA is oleic acid, which is present in olive oil in high amounts. Excellent sources of this healthy fat are avocados, nuts, seeds, canola oil, fish oils, and nut oils. Polyunsaturated fatty acids (PUFAs) are found in sunflower seeds, oily fish, walnuts, flaxseeds, and vegetable oils, including safflower, sunflower, and corn oils. Omega-3 and omega-6 are polyunsaturated fats. Omega-3 plays a crucial role in the production of hormones, in the immune system, blood clotting, and cellular growth. Studies show that consuming omega-3 fats is linked to reduced incidence of health conditions, including neurodegenerative disease, heart disease, and diabetes. High-density lipoproteins (HDL) are good cholesterol. These particles contain a high proportion of protein to cholesterol. They protect the body by carrying LDL cholesterol away from arteries to the liver, and they have anti-inflammatory properties. Low-density lipoproteins (LDL) are bad cholesterol. They have a lower proportion of protein to cholesterol. These types of fatty acids carry cholesterol to the cells. Too much LDL can be harmful because it sticks to the inside walls of your arteries, causing buildup of fatty material, limiting blood flow and leading to heart conditions and stroke. We want to aim for a preferential ratio between HDL and LDL cholesterol. There are measures we can take to increase our HDL cholesterol levels and lower LDL. Non Dietary actions include exercising regularly and stopping smoking. Avoid trans fats completely, and include the following foods regularly in your diet. Purple fruits and vegetables are rich in anthocyanins, which may help increase HDL cholesterol levels. Oily fish 1–2 times a week may help increase HDL cholesterol levels and benefit heart health. Olive oil increases HDL levels in healthy people, the elderly, and those with high LDL cholesterol. Whole grains are linked to a lower risk of heart disease. Oats and barley contain beta-glucan, which lowers LDL cholesterol. Nuts are rich in cholesterol-lowering fats and fiber, as well as minerals that are linked to improved heart health. Avocados contain monounsaturated fatty acids and fiber, both of which lower LDL cholesterol. Legumes such as beans, peas, and lentils help lower LDL levels and are a good source of plant-based proteins.
