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Nutrients -- What They Are and Why You Need Them

Nutrition Study Guide

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Updated June 09, 2014

Nutrients can be broken down into different types: macronutrients, micronutrients, and phytonutrients. Many of them are essential nutrients because your body can't make them, so you have to get them from the foods you eat.

Macronutrients: "Macro" means big. The macronutrients are the big nutrients, better known as protein, fats and carbohydrates. Everything you eat contains varying amounts of these nutrients. Despite the popularity of some fad diets that require you to reduce your intake of any one of these macronutrients, all of them are important for your health, and you need them every day.

Proteins are necessary for building the tissues in your body, including all the muscles, organs, skin and parts of the immune system. Your body can also use protein for energy or convert it to fat. Carbohydrates include sugar, starch and fiber. Sugars and starches are needed for the energy that your body needs to function every day. Extra carbohydrates are converted to fat.

Fats are needed for the membranes that surround all the cells in your body, for normal brain and nerve function, and for signaling hormones. Just like protein, the extra fat can be used as fuel for the body or can be stored as fat.

Micronutrients: "Micro" means small so the micronutrients are the nutrients that we need in small amounts. These include the 12 vitamins and 13 minerals that we need every day. Vitamins are categorized as water-soluble or fat-soluble depending on whether they can dissolve in fat or water. Minerals are divided into two groups, the major minerals and the trace minerals. They're available as dietary supplements, but be careful not to go over the tolerable upper levels.

Water-soluble vitamins include vitamin C and the seven B-complex vitamins. They have a variety of functions and you need all of them to be healthy. Chronic deficiencies of these vitamins can result in poor health.

Fat-soluble vitamins include vitamins A, D, E and K. Vitamins A and E come strictly from the foods you eat. However your body can make both vitamin D and vitamin K. Your body can store these vitamins in fat tissue. While it is extremely difficult to get too much of these vitamins from the foods you eat, you can build up toxic amounts of these four vitamins if you take massive amounts as dietary supplements every day.

Major minerals include calcium, phosphorus,chloride, magnesium, potassium and sodium. These minerals are particularly important for healthy bones, teeth, muscles and fluid balance in the body. The trace minerals are chromium, copper, fluoride, iodine, iron, selenium and zinc. Your body needs all of these minerals for a variety of processes to keep functioning.

Eating a healthy diet with lots of fruits, legumes, nuts, seeds, vegetables, whole grains, lean meats, poultry, fish and dairy products should provide you with all of the micronutrients you need. There are people who may need to take additional dietary supplements, such as women at risk of osteoporosis or people with age-related eye diseases. Always follow label directions if you take any dietary supplements.

Phytonutrients: "Phyto" refers to plants. Many different phytonutrients are found only in plants. Many of these natural chemicals are found in the colorful skins and flesh of fruits and vegetables. Some of the best known phytonutrients are the carotenoids, such as beta carotene, lutein, lycopene and zeaxanthin, plus flavonoids such as quercetin and anthocyanin.

Phytonutrients have a variety of functions in the body. Some of them may function as antioxidants that protect the cells in our bodies from free radical damage. Others, like falcarinol from carrots, may help to prevent cancer.

We don't know exactly how many of these different phytonutrients we need, however a healthy diet including at least five servings of fruits and colorful vegetables every day will supply your body with lots of phytonutrients.

Source:

Gropper SS, Smith JL, Groff JL. "Advanced Nutrition and Human Metabolism." Fourth Edition. Belmont, CA. Wadsworth Pub Co. 2005.

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