An ancient crop, lentils have had a place in human agriculture for more than 8,500 years, according to Purdue University. They make up a part of the protein food group, and the U.S. Department of Agriculture recommends eating legumes, including lentils, to increase the variety of protein sources in your diet. At 230 calories per 1-cup serving, boiled lentils offer energy to fuel your daily functioning, and they make a smart addition to your diet because of their broad nutrient profile.

High in Protein and Fiber

Lentils make a satisfying addition to meals because of their protein and fiber content. Fiber helps food remain in your stomach for longer after eating, keeping you feeling full for longer after your meal. A fiber-rich diet also softens your stool, which keeps you regular, and helps control your blood sugar. The protein in lentils provides amino acids -- compounds your body can reassemble into hormones, as well as use for new cell growth. A 1-cup serving of boiled lentils contains 15.6 grams of dietary fiber -- 41 percent of the daily fiber need for men and 60 percent for women, determined by the Institute of Medicine. Each cup also boasts 17.9 grams of protein, which is 39 percent of the daily intake for women and 32 percent for men, recommended by the USDA.

Rich Source of Folate and Pantothenic Acid

Lentils also make worthwhile meal additions because they're high in folate and pantothenic acid, two B-complex vitamins your cells need to function. Your cells use pantothenic acid to make coenzyme A, a chemical needed for brain function, energy production and hormone synthesis. The folate in lentils allows your cells to control gene activity, a process important for cancer prevention. Each cup of boiled lentils contains 1.26 milligrams of pantothenic acid and 358 micrograms of folate -- 25 percent and 90 percent of the recommended daily intakes, respectively, set by the Institute of Medicine.

Packed with Iron and Zinc

Add lentils to your diet to add nutritional value in the form of iron and zinc. A 1-cup portion of boiled lentils contains 2.5 milligram of zinc, which is 23 percent of the recommended daily intake for men and 31 percent for women. Eat a cup of lentils, and you'll also consume more iron -- 6.6 milligrams, which is 83 percent and 37 percent of the daily intakes recommended for men and women, respectively. The zinc in lentils helps maintain immune function and activates proteins that control gene activity in your cells. Iron from lentils gets utilized to make energy, and it gets incorporated into the proteins hemoglobin and myoglobin. Hemoglobin is involved in oxygen transport, while myoglobin helps store oxygen.

Versatile in the Kitchen

Lentils have a mild, slightly earthy flavor that works well in a variety of dishes. Keep a container of cooked lentils in your freezer, packaged in individual servings, and thaw them for use in soups, salads and chilli. Alternatively, make low-sodium lentil pilaf by cooking lentils in no-sodium chicken or vegetable broth, and then adding vegetables -- such as steamed broccoli and cauliflower, or roasted butternut squash and fennel -- for nutritional value and texture.