L-Carnitine and L-Citrulline Explained Simply for Beginners

Two names on the SodaSteel ingredient list sound like chemistry homework: L-Carnitine and L-Citrulline. Both are amino acid names, and both have charming word histories. This guide explains in plain language what an amino acid is, where these two names appear in foods, and why citrulline shares its name with a watermelon. We keep to vocabulary and kitchen information only. For the product overview, see What Is SodaSteel.

What is an amino acid?

Amino acids are small molecules that serve as building blocks in biology. Chemists give them that name because each one contains an amino group and a carboxylic acid group joined to a central carbon atom. Living things string amino acids together into long chains called proteins. Twenty amino acids are used for the standard protein-building code, but there are many more amino acids in nature that do not become part of proteins at all, and some of those still appear in foods and in laboratory studies.

The letter "L" at the front of a name, as in L-carnitine or L-citrulline, is a chemistry convention. Many amino acids exist in two mirror-image forms, like a left hand and a right hand. The L stands for "levo", from the Latin for left, and it labels the form that is most common in living things. If you see D-forms and L-forms on a chemistry page, that is the distinction being made.

Where the name carnitine comes from

Carnitine takes its name from the Latin word carnis, meaning flesh or meat. The compound was first isolated from meat extract in the early twentieth century, and the name stuck. In everyday food terms, red meat such as beef and lamb is the best-known source listed in nutrition references, with smaller amounts in pork, fish, poultry and dairy products. Plant foods generally contain very little.

• Beef and lamb: the classic examples in food tables.
• Pork, fish and poultry: present in smaller amounts.
• Milk and dairy: yogurt and cheese are listed too.

The NIH Office of Dietary Supplements maintains a helpful consumer guide to dietary supplements for readers who want to dig into labels and ingredient names.

Where the name citrulline comes from

Citrulline has a name with a fruity backstory. It was first isolated from watermelon in the 1930s, and the watermelon's Latin botanical name is Citrullus lanatus. The compound was named after the genus Citrullus, which is where the word comes from. Watermelon is a member of the gourd family, along with cucumbers, pumpkins and squash, and its rind and flesh are classic ingredients in summer cooking around the world.

Foods that appear in citrulline lists include watermelon, cucumbers, pumpkins and other members of the gourd family. In the kitchen, those are some of the most refreshing foods of the season.

• Watermelon wedges, cubes or frozen pops.
• Watermelon and feta salad with mint and lime.
• Cucumber salad with rice vinegar and sesame.
• Roasted pumpkin or squash soup.

Even the rind is used: pickled watermelon rind is a traditional preserve in several cuisines.

Amino acids on a food label and a supplement label

You will notice that foods are labeled with protein rather than individual amino acids. Protein-rich foods such as meat, dairy, eggs, beans and tofu contain a wide mix of amino acids, and the exact profile varies by food. A supplement label, by contrast, lists named ingredients such as L-Carnitine and L-Citrulline in a Supplement Facts panel. If you want a friendly walk-through of those panels, watch for our upcoming guide Gummy Supplements Explained, which covers how finished gummies are made and labeled. The FDA also provides general information on its dietary supplements page.

Fun facts for curious cooks

Word origins like these turn food shopping into a small adventure. Watermelon is roughly nine-tenths water and has been cultivated for thousands of years, with early images of the fruit appearing in ancient Egyptian art. Cucumbers, pumpkins and squash share the same broad family, and their flowers, seeds and shoots are used in kitchens from Mexico to India. On the carnitine side, the word came from a laboratory in the early twentieth century, but meat has been a part of human cooking for far longer. A taste for variety, rather than any single ingredient, is the secret of a happy kitchen. Try one new gourd, bean or cut of meat each month and see what you discover.

Plate ideas that bring these foods together

You do not need a laboratory to enjoy these foods. A few easy combinations show how ordinary the ingredients are.

• Beef and vegetable stir-fry with a cucumber side salad.
• Yogurt bowl with fruit and seeds for breakfast.
• Grilled chicken with a watermelon and mint salad in summer.
• Bean and squash chili for a cool evening.

The USDA MyPlate site shows how to build balanced plates with protein foods, vegetables, fruits, grains and dairy, and it is a practical companion to any list like this one. The post B Vitamins in Everyday Foods offers a parallel kitchen list.

L-Carnitine and L-Citrulline in the SodaSteel lineup

SodaSteel is a dietary supplement in gummy form, and the bottle artwork shows 60 gummies. The brand names nine ingredients: Vitamin B3, Vitamin B6, Zinc, L-Carnitine, L-Citrulline, Grape Seed Extract, Panax Ginseng, Maca Root and Rhodiola Rosea. Amounts are not published, so none are stated here. The brand describes the gummies as stimulant-free, non-GMO and gluten-free, and the bottle label reads "Supports Stamina", "Maintain Healthy Muscle" and "Maintain Energy". For the complete list, visit the ingredients page, and follow the serving directions printed on the bottle label.

Word origins make labels friendlier

Once you know that carnitine is the meat word and citrulline is the watermelon word, the names stop being intimidating. Chemistry vocabulary often hides a very down-to-earth story. When you are ready to compare bottles, the order page shows the current price and offer, the 60-day money-back guarantee, and pack options of 2, 3 and 6 bottles. Check today's offer on the order page