Inulin

Inulin is a natural chemical found in many plants. Plants use inulin to store energy, often in their roots or underground stems. Unlike some plants that store energy as starch, these plants use inulin instead.

Inulin belongs to a group called dietary fiber, specifically a type known as fructans. In 2018, the United States Food and Drug Administration allowed inulin to be added to foods to improve their nutritional value. Because of this, you might find inulin in many processed food products today.

Inulin is also important because doctors use it to check how well kidneys are working. When they need the most accurate way to measure kidney function, they use inulin as the best comparison method.

Origin and history

Inulin is a natural energy source found in more than 36,000 kinds of plants, such as agave, wheat, onion, bananas, garlic, asparagus, Jerusalem artichoke, and chicory. Plants use inulin to store energy and to help them survive cold weather. Because it can dissolve in water, inulin helps plants control the water inside their cells.

Inulin was first found in 1804 by a German scientist named Valentin Rose. He discovered it in the roots of a plant called Inula helenium. Later, scientists studied its structure. Inulin is also used by doctors to measure how well the kidneys are working.

Chemical structure and properties

Inulin is made of chains of a sugar called fructose. Our bodies can't break these chains down easily. This means inulin doesn't give us many calories and works like dietary fiber, which is good for us.

Inulin has no color or smell, so it doesn't change how food tastes or looks. Some types of inulin are a little sweet, like table sugar, while others aren't sweet at all. Inulin mixes well with liquids and can make a thick, creamy texture like fat. This helps keep foods stable and can help keep mixtures mixed.

Uses

Harvesting and extraction

Chicory root is the main source for getting inulin for commercial use. The process to get inulin is similar to how we get sugar from sugar beets. After harvesting, the chicory roots are sliced, washed, and soaked in a solvent like hot water or ethanol. The inulin is then separated, cleaned, and dried. Inulin can also be made from sucrose.

Processed foods

Inulin is safe to use in foods, as approved by the U.S. Food and Drug Administration. It is used in many processed foods because it works well in manufacturing. It can add fiber to foods and tastes only a little sweet—about 10% as sweet as sugar. Inulin can replace sugar, fat, and flour in recipes. It has less energy than regular carbohydrates and can help the body absorb important minerals like calcium and possibly magnesium. It also helps good bacteria grow in the digestive system.

Medical

Inulin is used by doctors to check how well kidneys are working. This is done by measuring how much fluid the kidneys filter each minute. Although inulin is the best way to do this test, it is not used often because it is expensive and needs many blood samples over several hours.

Possible side effects

When eaten in larger amounts, inulin can cause some stomach problems like bloating, gas, and diarrhea.

Industrial use

Inulin can be turned into ethanol, a type of fuel, through a special process. This could help make fuel from plants that have a lot of inulin.

Biochemistry

Inulins are special sugars made mostly from a sugar called fructose. They are formed by linking fructose units together in a straight chain. These chains can be short with just a few fructose units, or very long with up to around 200 units. Inulins can have a small piece of another sugar, glucose, at the end, or they might not. Inulins are stored forms of energy in many plants.

Calculation of glomerular filtration rate

Inulin is special because it moves through a part of the kidney called the glomerulus without being changed. This helps doctors measure how much blood the kidneys filter each minute, called the glomerular filtration rate (GFR).

Doctors used to use inulin often for this test, but now they use simpler ways, like measuring creatinine in the blood and urine. Inulin must be given through an infusion, which can be tricky, but it helps doctors know exactly how much inulin was given.

Metabolism in vivo

Inulin is a type of fiber that our bodies cannot easily break down. It passes through most of our digestive system without being digested. Only in the lower part, called the colon, special tiny living things called bacteria break down inulin. This releases gases like carbon dioxide, hydrogen, and methane.

Inulin is a soluble fiber, meaning it dissolves in water. Soluble fibers can help keep our blood health good by possibly lowering cholesterol and sugar levels. Because our body cannot break down inulin into simple sugars, it does not raise blood sugar levels. This can be good for people with diabetes. Inulin also helps friendly bacteria in our gut grow. It moves through the stomach and the first part of the small intestine without being digested, making it ready for the bacteria in the gut to use.

Some traditional foods contain a lot of inulin, like chicory, garlic, and leek. These foods have been valued for good health for many years. Studies have shown that inulin can sometimes cause stomach problems like bloating and gas, but it might also help prevent certain travel illnesses and improve how the body absorbs important minerals like calcium.

Natural sources

Many foods contain inulin, a special sugar stored by plants. Some of these foods include chicory root, which has up to 18 grams per 100 grams, and Jerusalem artichoke with up to 13 grams per 100 grams. Other foods with inulin are dandelion greens, garlic, leeks, onions, asparagus, wheat bran, barley, and bananas.