A Guide to the Essential Nutrients — and Why Your Body Needs Them
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It's no secret that foods such as fruits, veggies, and whole grains are integral components of a healthy diet. But what makes these eats so good for you, exactly? It's all thanks to their essential nutrients, aka compounds you need to survive but your body can't make on its own. Specifically, "essential nutrients are important for overall health because [we need them for] a healthy functioning body," notes Andrea Mathis, M.A., R.D.N., L.D., registered dietitian and founder of Beautiful Eats & Things. Not only are essential nutrients vital for overall good health, but, according to the World Health Organization, they're also key for growth, reproduction, and disease prevention.
Essential nutrients are classified as either macronutrients or micronutrients. Quick refresher: Macronutrients are consumed in relatively large quantities and include carbohydrates, protein, and fat — all of which provide your body with energy (via calories). Micronutrients, on the other hand, are needed in small amounts and consist of vitamins and minerals. And then there's water, an essential nutrient that's in a league of its own.
Now, if you've been keeping count, you've likely realized that there are six essential nutrients: carbohydrates, protein, fat, vitamins, minerals, and water. But why are these bad boys in particular considered essential? Read on for a deep dive into essential nutrients, below.
Carbohydrates
Despite the seemingly perpetual low-carb craze, carbohydrates are actually pretty darn good for your body. For one, when digested, carbs break down into a type of monosaccharide (aka sugar molecule) called glucose. Sound familiar? That's because glucose is the body's main source of energy; meaning, it (and, thus, carbs) help vital organs, such as the kidneys, function properly, explains Mathis.
Carbs also preserve muscle mass, according to Oklahoma State University Extension. Basically, if you don't eat enough carbs (and therefore, glucose), the liver is forced to break down protein in your muscle and convert it into glucose, triggering muscle loss, according to a 2019 scientific review. Consuming enough carbs, however, can protect said muscle, as it prevents the body from tapping into it for protein for fuel.
And need not forget fiber, a type of carb with a myriad of functions. Soluble fiber (which dissolves in water) manages healthy blood cholesterol levels, thus protecting the heart. It also bulks up the stool, making it easier to pass and potentially easing constipation, according to the University of California San Francisco. Meanwhile, insoluble fiber (which doesn't dissolve in water) promotes the movement of food in your GI tract, helping you stay regular.
Recommended Intake
Given carbohydrate's range of important functions, it's no surprise that most of your energy (aka caloric) intake should come from this nutrient. In fact, according to the 2020 to 2025 Dietary Guidelines for Americans, adults should get 45 to 65 percent of their daily calories from carbohydrates. This equals about 130 grams of carbs per day — a number that might be higher or lower depending on your overall caloric needs.
Sources
Not all carbs are equal. ICYDK, carbohydrates fall into two categories: simple carbs (think: white-flour products, candy, sugar-sweetened beverages) and complex carbs (think: whole grains, beans, veggies). Unlike simple carbs, complex ones are generally higher in fiber and digest more slowly, thereby providing a steady flow of energy and keeping you fuller for longer. So, while there's no reason to write off a good old bowl of pasta, know that complex carbs are typically the healthier option when it comes to filling up on this essential nutrient.
Protein
When it comes to nutrition, protein gets a lot of attention — and for good reason. See, protein is required to keep seemingly every part of your body running smoothly. In fact, it's often considered the body's "building blocks," as it provides structure to cells and tissues (e.g. muscles, organs), according to the National Center for Biotechnology Information (NCBI). What's more, protein also "allows [the] body to repair cells and make new ones," says Mathis, making the nutrient especially crucial during periods of development, such as puberty and pregnancy. But that's not all: The essential macronutrient is also needed to transport other compounds (think: oxygen), clot blood to prevent excessive bleeding, and contract muscles during movement, according to the Academy of Nutrition and Dietetics.
It's also important to note that protein is made from small compounds known as amino acids, according to Harvard T.H. Chan School of Public Health. And while the body can create some amino acids on its own (called non-essential amino acids), it needs to get many of them (essential amino acids) from food, namely those rich in protein.
Recommended Intake
While your protein needs depend on many factors, including your age and activity level, according to the 2020 to 2025 Dietary Guidelines for Americans, adults should get about 10 to 35 percent of their daily calories from protein. More specifically, the average person needs a minimum of 0.8 grams of protein per kilogram of body weight (or 0.36 grams of protein per pound of body weight), according to Marissa Meshulam, M.S., R.D., C.D.N., registered dietitian and founder of MPM Nutrition. For athletes, that rec is bumped up to 1.2 to 2 grams of protein per kilogram of body weight (or 0.55 to 0.9 grams of protein per pound), she adds. That's because physical activity breaks down muscle tissue, and protein is needed to help repair it, according to the Academy of Nutrition and Dietetics. (Related: What Eating the *Right* Amount of Protein Every Day Actually Looks Like)
Sources
Protein sources include meat, dairy, and legumes, plus some veggies and grains. But Mathis says that leaner protein — e.g. poultry sans-skin, seafood, eggs, legumes, nuts, soy — is the healthiest choice, as it contains little to no saturated fat (more on that below). Animal sources and some plants (looking at you, soy and quinoa) are considered complete proteins, meaning they contain all nine essential amino acids, according to NCBI. Other plant sources, such as nuts, are incomplete proteins, as they only offer some of those amino acids. However, as long as you're getting varied plant proteins throughout the day, you'll be able to get all the essential amino acids you need, notes Meshulam.
Fat
Though fat often gets a bad rap, it actually has numerous vital functions in the body. Fat stores and provides energy, gives structure to cells, and supports the absorption of fat-soluble vitamins (e.g. vitamins A, D, E, and K), according to NCBI. Plus, when digested, it (along with protein and fiber) is responsible for the sense of satisfaction and fullness, according to Meshulam.
There are only two types of fats that are considered essential for humans. "Our bodies can create some fatty acids, meaning [these fats] are not essential in our diet," explains Meshulam. However, the body can't make omega-3 and omega-6 fatty acids, so you need to get them via food, she adds. These fats, appropriately called essential fatty acids, are unsaturated or "good" fats, according to Harvard T.H. Chan School of Public Health. In the body, they support healthy heart rhythms and blood cholesterol levels, making them beneficial for cardiovascular health. Omega-3 fatty acids boost particularly potent anti-inflammatory properties, which may help thwart inflammation-driven conditions like diabetes and heart disease, according to Oregon State University. This is a far cry from saturated and trans fats, aka "bad fats," which have been linked to high blood cholesterol levels and heart disease. (Related: The Expert-Approved Guide to Good Fats vs. Bad Fats)
Recommended Intake
Adults should get 20 to 35 percent of their daily calories from fat, according to the 2020 to 2025 Dietary Guidelines for Americans. But again, not all types of fat are equal. In fact, the guidelines recommend that less than 10 percent of daily calories should come from saturated fat, which can be achieved by replacing saturated fat with the unsaturated kind (again, omega-3 and omega-6) whenever possible. It's also recommended to get more omega-3s than omega-6s, as this ratio is key for reducing inflammation, according to a 2018 article in BMJ Journals. (Most people already get enough omega-6s, but many tend to be low in the omega-3 department, says Meshulam.)
Sources
Unsaturated fats can benefit the heart and overall health when they're eaten in place of foods high in saturated fat (such as red meats and many processed foods). To fuel up on "good" fats, reach for eats such as nuts and seeds, as well as their oils. Foods such as fatty fish (i.e., salmon), chia seeds, and walnuts are especially high in omega-3 fatty acids, according to Meshulam. (See also: Everything You Need to Know About Omega-3s and Omega-6s)
Vitamins
Now, it's time to talk about the essential micronutrients, beginning with vitamins. A quick recap: Unlike carbohydrates, protein, and fat, micronutrients are needed in small amounts and don't provide any calories. Still, they're vital components of a healthy diet, as the body can't make them (or, in some cases, can't make enough of them) on its own, according to NCBI. There are 13 essential vitamins, which are categorized into two groups — fat-soluble and water-soluble vitamins — depending on how they're handled by the body.
Fat-soluble vitamins, such as vitamins A, D, E, and K, are stored in fat, so they can easily accumulate in fat tissue. And while each nutrient has a unique purpose, in general, fat-soluble vitamins are involved in functions such as vision, immunity, and bone health, according to NCBI. Meanwhile, water-soluble vitamins need to dissolve in water in the body. This means water-soluble vitamins aren't easily stored, and any excess nutrients will leave the body via the urine, according to Harvard T.H. Chan School of Public Health. Water-soluble vitamins include vitamin C — a major player in immunity and collagen production — and the B vitamins — which are needed to repair DNA, produce energy, and support brain function.
Recommended Intake
Here are the daily recommended intakes of vitamins for adults, according to NCBI:
Vitamin A: 700 micrograms (women), 900 micrograms (men)
Vitamin D: 10 to 15 micrograms
Vitamin E: 15 milligrams
Vitamin K: 90 micrograms (women), 120 micrograms (men)
Vitamin C: 75 milligrams (women), 90 milligrams (men)
Thiamine (B1): 1.1 milligrams (women), 1.2 milligrams for men
Riboflavin (B2): 1.1 milligrams (women), 1.3 milligrams (men)
Niacin (B3): 14 milligrams (women), 16 milligrams (men)
Pantothenic acid (B5): 5 milligrams
Pyridoxine (B6): 1.3 milligrams
Biotin (B7): 30 micrograms
Folate (B9): 400 micrograms (800 micrograms for pregnant people)
Cobalamin (B12): 2.4 micrograms
Sources
Some plant foods are higher in certain nutrients (think: citrus fruits and vitamin C), but in general, eating a diet full of nutrient-dense foods is the best way to get all the vitamins you need, according to the 2020 to 2025 Dietary Guidelines for Americans. This includes plenty of fruits, veggies, whole grains, lean proteins, and unsaturated fats.
In some cases, you might need to rely on supplements as vitamin sources. "For example, [if you] follow a vegan diet, [you] may need to supplement with vitamin B12," says Mathis. "Vitamin B12 is mainly found in animal products like meat, milk, and other dairy products," which are omitted in vegan diets. But remember: Supplements are not regulated by the Food and Drug Administration, so it's especially important to talk to your doc before adding anything to your routine. (See more: Are Dietary Supplements Really Safe?)
Minerals
Minerals are classified into two groups based on how much the body needs. First up are macrominerals, including calcium, magnesium, phosphorus, sodium, potassium, and chloride, which are needed in larger amounts — more than 100 milligrams per day — according to NCBI. On the flip side, microminerals, also called trace minerals, are needed in smaller amounts — less than 100 milligrams per day. Microminerals include iron, zinc, copper, iodine, and selenium. Like vitamins, each mineral specializes in different functions within the body. But overall, these micronutrients "are involved in the growth of our bones and teeth, [as well as] the function of our hearts, brains, and muscles," says Meshulam. They also support fluid balance, nerve cell communication, and blood health, according to the NLM.
Recommended Intake
Here are the recommended daily intakes for adults, according to NCBI:
Calcium: 1,200 milligrams (women), 1,000 milligrams (men)
Phosphorous: 700 milligrams
Magnesium: 400 milligrams
Sodium: 1,500 milligrams
Potassium: 4,700 milligrams
Chloride: 1,500 milligrams
Iron: 8 to 18 milligrams
Copper: 1 milligram
Zinc: 10 milligrams
Selenium: 55 micrograms
Iodine: 150 micrograms
BTW, your specific needs depend on your current health status. For example, you might need more iron during menstruation, as menstrual bleeding reduces your levels of the mineral, says Meshulam. The same goes during pregnancy, as extra iron is needed to make more blood and support the baby's development, according to NIH. Likewise, calcium absorption drops during menopause, which can lead to bone loss. This increases your calcium needs, according to the NIH. All that said, your doc can let you know when and if you need more of a certain mineral based on your medical conditions and/or certain blood tests.
Sources
As with vitamins, you'll get all the minerals you need if you eat a diverse and balanced diet. To recap, this includes plenty of fruits, vegetables, whole grains, lean protein, and "good" fats.
Water
Yes, you read that right: Water is considered one of the six essential nutrients. That's because water is required for vital bodily processes, including the regulation of body temperature and blood volume, according to the Academy of Nutrition and Dietetics. It's also needed to carry nutrients and oxygen between cells, lubricate the joints, and excrete waste via sweat and urine. What's more, water is the most abundant substance in your body; it makes up to a whopping 60 percent of your body weight, says Meshulam.
However, "you lose water through normal bodily functions, [like] sweating, breathing, and digesting," says Meshulam. And since the body can't make its own fresh water, you need to replenish its supply every single day. In fact, losing just 1.5 percent of your body's water can spark mild dehydration, leading to unpleasant symptoms such as fatigue and headache. Consider this: A person could live without food for six weeks, but only one week(ish) without H2O, according to the Academy of Nutrition and Dietetics.
Recommended Intake
The general rule of thumb is to divide your weight in pounds by two, then drink that amount in ounces, says Meshulam. "So, for a 140-pound person, that would be 70 ounces [of water per day]," she says. You'll need more water if you've been losing a lot of fluids, which can happen after vomiting, diarrhea, excessive sweating during exercise, or just moving around in hot weather, according to the Centers for Disease Control and Prevention. On that note, if you work out regularly, you'll definitely need to up your daily water intake, adds Meshulum. There isn't an exact guideline for how much more you should drink, because everyone sweats at different rates, which dictates how much water needs to be replenished, she explains. But generally speaking, the more you sweat, the more H2O you'll need to consume.
Sources
The best source of water is, well, water! However, drinks without added sugars (e.g. plain tea or 100-percent vegetable juice) can also help keep you hydrated, according to the CDC. When possible, choose these drinks over sugary beverages (see: soda), which contain extra cals and little nutrients. Similarly, try to sip on H2O while drinking alcohol, as the latter can increase urination and dehydration risk, according to Harvard T.H. Chan School of Public Health. Not a fan of plain H2O? Try flavoring your water with natural ingredients, such as crushed berries or fresh mint. (See more: These Infused Water Recipes Upgrade Your H2O with Barely Any Effort)
