Scientists agree that there are six primary nutrients that the human body cannot produce. Therefore, people need to get them from a range of foods in order to stay healthy.
The World Health Organization (WHO) classifies nutrients as either micro- or macronutrients. Micronutrients are those needed in small doses, such as vitamins and minerals.
Macronutrients, on the other hand, are those that are often consumed in large quantities, including proteins, fats and carbohydrates. Water also belongs to this group.
People need to consume all six, as each one supports a range of important cellular processes, from protein synthesis to reproduction.
Read on to learn about the specific functions, health benefits and food sources for each one:
Vitamins are organic compounds that the human body requires in relatively small quantities. This is because it either does not produce enough of the nutrient or does not produce that nutrient at all.
For instance, humans can make vitamin D from sunlight through their kidneys and vitamin K through gut bacteria. But these organs make so little that a person should still eat foods rich in the nutrients or take supplements in order to avoid nutritional deficiencies.
Some of the important functions and health benefits of vitamins include boosting immune health, slashing cancer risk, strengthening bones, supporting blood circulation and maintaining efficient neural connections.
There are 13 essential vitamins in total. These include vitamins A, C, D, E and K. The remaining eight vitamins make up the vitamin B complex that acts as an important building block of a healthy body.
These include thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), B6, biotin (B7), folate (B9) and cyanocobalamin (B12).
Vitamins can be found in abundance in plant-based foods like fruits, vegetables, legumes, nuts and grains.
Much like vitamins, minerals are essential for a number of functions, including bone formation and metabolism. Minerals can also be classified as either a major mineral or a trace mineral.
Major minerals, like magnesium, calcium, phosphorus, sodium and potassium, are those that support bone formation, maintain hydration and support skin health.
Trace minerals, on the other hand, are those needed to regulate blood clots, reduce blood pressure, boost blood circulation and support immune health. Notable trace minerals include iron, selenium, zinc, manganese, copper and iodine.
Minerals can be found in plant-based foods like fruits, salad greens, grains, beans, legumes, nuts and seeds. That said, some animal products also contain modest amounts of minerals. These include lean meat, seafood, milk, cheese, eggs and chicken.
Protein is the building block of skin, muscles, bones, nails and hair. On top of providing structural support to tissues and organs, protein also aids in forming antibodies, hormones and other essential substances needed for different processes. It also doubles as a fuel source for cells and tissues if needed.
Some of the major sources of protein are lean meats, poultry, fish, seafood, eggs and other animal products. It can also be found in a number of plant-based foods, including beans, legumes, nuts, seeds and some grains.
Fats often get linked to junk foods and bad health, but people forget that not all fats are the same. In fact, the human body needs a certain amount of fat to maintain optimal health, including brain health and joint health. That being said, it's important to distinguish the good fats from the bad ones.
Good or healthful fats, like monounsaturated and polyunsaturated fats, are those that aid in muscle movement, hormone production, immune response and blood sugar regulation. These can be found in nuts, seeds, coconut oil, olive oil, avocados and fish.
On the other hand, bad fats, like trans fats and saturated fats, are those that raise the risk of heart conditions. Fried and processed foods are abundant in these fats. Steer clear of them as much as possible.
Carbohydrates are the body's primary energy source. These nutrients act as fuel for involuntary but important body functions, like the beating of the heart, breathing and digestive processes.
Like fats, there are also good and bad sources of carbohydrates. The good ones are called complex carbohydrates, and they come from whole grains and whole-grain foods, such as quinoa, brown rice, whole-grain pasta, whole-wheat bread and oatmeal.
Bad ones, called simple carbohydrates, are those that come from refined grains and processed grain products, such as white bread, white rice, white flour and white pasta.
The body of the average human adult is about 60 percent water, according to the United States Geological Survey (USGS). The lungs are composed of the most water at 83 percent, followed by the brain and the heart at 73 percent. Even bones hold some water at 31 percent.
Because it makes up a considerable chunk of various vital organs, even the slightest dehydration can cause side effects, like headaches and fatigue. (Related: Could you be suffering from a dehydration headache?)
On top of keeping the body hydrated, water also helps in flushing out toxins, transporting nutrients and lubricating the joints to keep them flexible.
Although not strictly a nutrient, the Institute of Medicine (IOM) of the National Academy of Sciences (NAS) recommends that adult men should drink at least 101 ounces (oz) or about 13 cups of water every day.
Women should drink at least 74 oz or a little more than nine cups, and children should drink anywhere between five to 11 cups a day depending on their age group.
People need to get all six essential nutrients in order to maintain optimal health. Make sure to drink enough water and to eat healthful food sources of vitamins, minerals, fats, protein and carbohydrates.