Iron is an essential trace mineral -- one that’s needed only in small amounts, but it plays a major role in how the body works and how you feel. Without adequate iron, the body can’t make red blood cells to carry oxygen, and you may feel more tired than usual, frequently dizzy or out of breath.

The muscular tongue functions in chewing, tasting and swallowing. Because of its nearly continuous use throughout the day, abnormalities become obvious very quickly, making the tongue a helpful marker of disease.

Approximately 29 percent of children in the United States take a dietary supplement that contains vitamin C, according to a survey published in the October 2007 issue of “Archives of Pediatric and Adolescent Medicine.

Eating a diet filled with fruits and vegetables will help keep your lungs healthy. This type of diet may lower your risk for lung cancer, one of the types of cancer with a relatively low survival rate.

Fish oil for supplements come from cold-water fish, such as salmon, anchovies, tuna, trout, mackerel and halibut. They contain compounds called omega-3 fatty acids, which are associated with several health benefits.

As a breastfeeding mother, you probably think about everything you consume in terms of the effect it will have on your breastfed baby. If you eat a lot of fruits and vegetables high in vitamin C or take supplements with this nutrient, you might wonder whether high doses could affect you or your infant.

Biotin, also known as vitamin H or B7, is a water-soluble complex vitamin that is vital for strong, healthy hair and nails, and can be found in foods like almonds, eggs, liver, pecans, sardines and whole grains.

Vitamins come in two varieties: water soluble and fat soluble. Water soluble vitamins, such as B complex vitamins and vitamin C, dissolve in water and are excreted through the kidneys if you have excess amounts in your body.

Vitamin C is a water-soluble vitamin that is found in many fruits and vegetables. Vitamin C plays an important role in collagen formation, and it also functions as an antioxidant, boosting the immune system. Although you need to consume vitamin C every day, too much can be toxic.

Ester C is a pH neutral product which has a different composition from regular vitamin C, which is ascorbic acid. The main component of this product is calcium ascorbate. Other ingredients of Ester C are compounds known as vitamin C metabolites, which are dehydroascorbic acid and calcium threonate.

While it's always best to get nutrients from food sources, these are the supplements that can help you get well-rounded nutrition while on the keto diet.

While the whole health picture is more complex than eating an apple a day to keep the doctor away, fruits and vegetables undeniably supply nutrition vital for good health. Apples, whether whole or as applesauce, contain fiber and vitamin C.