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Medicine LibreTexts

3.1: Nutrition Basics

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    13342
  • What is your food made of?

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    Food provides the energy and nutrients you need to be healthy.

    Nutrients include:

    • protein

    • carbohydrates

    • fats

    • vitamins

    • minerals

    • water

    Energy of Food

    When energy is used to describe the foods you consume, energy is referring to calories. Calories are what provides the body with the energy it needs to survive and stay healthy. Our body uses calories to breathe, think, and talk. We also use calories to exercise! The three categories of nutrients that provide us with calories, or energy, are Proteins, Carbohydrates, and Fats. If you were to go to McDonalds and eat a Big Mac you would be consuming 540 calories. How much of those calories come from Proteins, Carbohydrates, and Fats?

    Protein

    Protein is in every cell in the body. Our bodies need protein from the foods we eat to build and maintain bones, muscles and skin. We get proteins in our diet from meat, dairy products, nuts, and certain grains and beans. Proteins from meat and other animal products are complete proteins. This means they supply all of the amino acids the body can’t make on its own. Most plant proteins are incomplete. You should eat different types of plant proteins every day to get all of the amino acids your body needs.

    It is important to get enough dietary protein. You need to eat protein every day, because your body doesn’t store it the way it stores fats or carbohydrates. How much you need depends on your age, sex, health, and level of physical activity. Most Americans eat enough protein in their diet.

    Protein provides us with 4 calories per gram consumed. If you eat a Big Mac from McDonald's, it will provide you with 25 grams of protein. 25 grams of protein is equal to 100 calories, therefore 100 calories of the 540 total calories from a Big Mac come from proteins. Big Mac’s are 19% protein.

    Carbohydrates

    Carbohydrates are one of the main types of nutrients. They are the most important source of energy for your body. Your digestive system changes carbohydrates into glucose (blood sugar). Your body uses this sugar for energy for your cells, tissues and organs. It stores any extra sugar in your liver and muscles for when it is needed.

    Carbohydrates are called simple or complex, depending on their chemical structure. Simple carbohydrates include sugars found naturally in foods such as fruits, vegetables, milk, and milk products. They also include sugars added during food processing and refining. Complex carbohydrates include whole grain breads and cereals, starchy vegetables and legumes. Many of the complex carbohydrates are good sources of fiber.

    Fiber is commonly classified as soluble, which dissolves in water, or insoluble, which doesn’t dissolve.

    • Soluble fiber. This type of fiber dissolves in water to form a gel-like material. It can help lower blood cholesterol and glucose levels. Soluble fiber is found in oats, barley, nuts, seeds, beans, lentils, peas, and some fruits and vegetables.

    • Insoluble fiber. This type of fiber promotes the movement of material through your digestive system and adds bulk to the stool, so it can be of benefit to those who struggle with constipation or irregular stools. Insoluble fiber is found in foods such as wheat bran, vegetables, and whole grains.

    For a healthy diet, limit the amount of added sugar that you eat and choose whole grains over refined grains.

    Carbohydrates provide us with 4 calories per gram consumed. If you eat a Big Mac from McDonald's, it will provide you with 46 grams of carbohydrates. 46 grams of protein is equal to 184 calories, therefore 184 calories of the 540 total calories from a Big Mac come from carbohydrates. Big Mac’s are 34% carbohydrates.

    Fats

    We need a certain amount of fat in our diets to stay healthy. Fats provide needed energy in the form of calories. Fats help our bodies absorb important vitamins—called fat-soluble vitamins—including vitamins A, D and E. Fats also make foods more flavorful and help us feel full. Fats are especially important for infants and toddlers, because dietary fat contributes to proper growth and development.

    Problems arise, though, if we eat too much fat. Dietary fats have more than twice as many calories per gram as either proteins or carbohydrates like sugar and starch. Excess calories, of course, can pack on the pounds and raise your risk for diabetes, cancer and other conditions.

    Foods can contain a mixture of different fats. Unsaturated fats are considered “good” fats. They’re sometimes listed as “monounsaturated” and “polyunsaturated” fat on Nutrition Facts labels. These can promote health if eaten in the right amounts. They are generally liquid at room temperature, and are known as oils. You’ll find healthful unsaturated fats in fish, nuts and most vegetable oils, including canola, corn, olive and safflower oils.

    The so-called “bad” fats are saturated fats and trans fats. They tend to be solid at room temperature. Solid fats include butter, meat fats, stick margarine, shortening, and coconut and palm oils. They’re often found in chocolates, baked goods, and deep-fried and processed foods.

    Fats provide us with 9 calories per gram consumed. If you eat a Big Mac from McDonald's, it will provide you with 28 grams of fats. 28 grams of fat is equal to 252 calories, therefore 252 calories of the 540 total calories from a Big Mac come from fats. Big Mac’s are 47% fats.

    Example: McDonald’s Big Mac

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    540 total calories

    • Proteins = 25 grams = 100 calories = 19%

    • Carbohydrates = 46 grams = 184 calories = 34%

    • Fats = 28 grams = 252 calories = 47%

    *Note: Many times the total calories from breaking down the macronutrients will not match the total calories and this is due to rounding the numbers.

    We know the Big Mac provides us with a lot of Fat, but what kind of Fat is it? Is it good fat or bad fat? We can try to determine this by looking at the breakdown of Fats. The nutrition label tells us that 10 grams of the 28 grams comes from Saturated Fat and 1 grams comes from trans Fats.

    To see the food label of your favorite foods check out http://www.calorieking.com/foods/

    For additional information about fats check out “The truth about fats: the good, the bad, and the in-between” from Harvard Health Publishing available at: https://www.health.harvard.edu/staying-healthy/the-truth-about-fats-bad-and-good

    Vitamins

    Vitamins are substances that your body needs to grow and develop normally. There are 13 vitamins your body needs. They are:

    Vitamins are classified as either fat soluble (vitamins A, D, E and K) or water soluble (vitamins B and C). This difference between the two groups is very important as it determines how each vitamin acts within the body.

    You can usually get all your vitamins from the foods you eat. Your body can also make vitamins D and K. People who eat a vegetarian diet may need to take a vitamin B12 supplement.

    Each vitamin has specific jobs. If you have low levels of certain vitamins, you may get health problems. For example, if you don’t get enough vitamin C, you could become anemic. Some vitamins may help prevent medical problems. Vitamin A prevents night blindness.

    The best way to get enough vitamins is to eat a balanced diet with a variety of foods. In some cases, you may need to take vitamin supplements. It’s a good idea to ask your healthcare provider first. High doses of some vitamins can cause problems.

    Minerals

    Minerals are important for your body to stay healthy. Your body uses minerals for many different jobs, including building bones, making hormones and regulating your heartbeat.
    There are two kinds of minerals: macrominerals and trace minerals. Macrominerals are minerals your body needs in larger amounts. They include calcium, phosphorus, magnesium, sodium, potassium, chloride and sulfur. Your body needs just small amounts of trace minerals. These include iron, manganese, copper, iodine, zinc, cobalt, fluoride and selenium.

    Water

    Water is your body’s principal chemical component and makes up about 60 percent of your body weight. Every system in your body depends on water. For example, water flushes toxins out of vital organs, carries nutrients to your cells, and provides a moist environment for ear, nose and throat tissues.

    Lack of water can lead to dehydration, a condition that occurs when you don’t have enough water in your body to carry out normal functions. Even mild dehydration can drain your energy and make you tired.

    Every day you lose water through your breath, perspiration, urine and bowel movements. For your body to function properly, you must replenish its water supply by consuming beverages and foods that contain water.

    What are Antioxidants?

    Antioxidants are substances we consume that may help to reduce cell damage. Antioxidants may come from the foods we eat or from dietary supplements.

    Examples of antioxidants include

    • Beta-carotene

    • Lutein

    • Lycopene

    • Selenium

    • Vitamin A

    • Vitamin C

    • Vitamin E

    Antioxidants may help to reduce cell damage caused by free radicals. Free radicals are highly unstable molecules that are naturally formed when you exercise and when your body converts food into energy. Free radicals have been shown to cause “oxidative stress” in the body thus damaging healthy cells. Although not conclusive, research shows that antioxidants work to reduce the chances of cellular damage. Because antioxidants help to reduce cell damage, it had been theorized that they in turn help to reduce chances of many diseases, including cancer.

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