Ketone bodies facts for kids
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Ketone bodies are special water-soluble molecules. Your liver makes them from fatty acids. They are like backup fuel for your body.
When your body doesn't have enough sugar (glucose) for energy, it turns to fat. The liver then breaks down fat into these ketone bodies. They can travel through your blood to other parts of your body. There, they are used to create energy.
The main types of ketone bodies are acetoacetic acid, beta-hydroxybutyrate, and acetone. Acetone is a natural byproduct of acetoacetate. You might know acetone as a chemical in nail polish remover!
Your body makes ketone bodies in several situations. This happens when you haven't eaten for a while (fasting). It also occurs during diets with very few carbohydrates. Long periods of intense exercise can also trigger their production. In some health conditions, like type 1 diabetes that isn't managed well, ketone bodies can also build up.
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How Your Body Makes Ketone Bodies
Your body stores fat in special fat cells. When your body needs energy, these fats are released into your blood. This happens when your insulin levels are low. It also occurs when other hormones, like glucagon, are high. This is common between meals, during fasting, or after lots of exercise.
These fats are a great source of energy. Most cells in your body can use them. Inside your cells, fats are broken down into smaller units called acetyl-CoA. These units then go into a process called the citric acid cycle. This cycle helps create energy for your cells.
However, your liver is a bit different. During times of low sugar, the liver uses its resources to make new sugar. This means it can't use all the acetyl-CoA for its own energy. Instead, the liver converts these acetyl-CoA units into ketone bodies.
The liver then releases these ketone bodies into your blood. Other parts of your body, like your muscles and brain, can pick them up. They convert the ketone bodies back into acetyl-CoA. Then, they use them for energy in their own citric acid cycles.
One important thing about ketone bodies is that they can cross the blood–brain barrier. This means they can reach your brain. Your brain normally relies on sugar for fuel. But when sugar is low, ketone bodies become a vital alternative energy source for your brain cells.
Sometimes, when there are many ketone bodies in the blood, it can cause a specific smell. This smell is often described as fruity. It can also smell like nail polish remover because of the acetone. You might notice this smell on someone's breath.
How Different Organs Use Ketone Bodies
Ketone bodies are like a versatile fuel. Many organs in your body can use them for energy. This includes your heart, brain, and muscles. However, your liver, which makes them, cannot use them for energy. This is because the liver lacks a specific enzyme needed for this process.
The Heart's Energy Choice
Normally, your heart gets most of its energy from fatty acids. But when your body is in a state where it's using a lot of ketones, your heart actually prefers to burn ketone bodies. It's a very efficient fuel for the heart.
The Brain's Backup Fuel
Your brain usually runs on glucose (sugar). But if there isn't much glucose available, the brain can switch to using ketone bodies. This is very important during times of fasting or when following a low-carb diet.
After a few days of strict fasting, ketone bodies can provide about a quarter of the brain's energy. If fasting continues for longer, ketone bodies can become the main fuel. They can supply up to two-thirds of the brain's energy needs. This ability to use ketones was important for the development of the human brain over time.
Research also suggests that ketones made from certain healthy fats, like omega-3 fatty acids, might help protect the brain. They could help reduce problems with thinking and memory as people get older.
Ketosis and Ketoacidosis: What's the Difference?
Your body always produces and uses some ketone bodies. Their level in your blood is usually very low.
When your body makes more ketone bodies than it uses, their level in the blood goes up. This condition is called ketonemia. If these extra ketones start to show up in your urine, it's called ketonuria. Together, ketonemia and ketonuria are known as ketosis. The fruity or nail polish remover smell on the breath is a common sign of ketosis.
Nutritional ketosis is a mild form of ketosis. It happens when people follow a low-carbohydrate diet. In this state, ketone levels are moderately increased. This is generally considered a normal and safe adaptation.
However, there is a very serious condition called diabetic ketoacidosis. This mostly affects people with type 1 diabetes if they don't have enough insulin. In this situation, ketone levels become extremely high. This makes the blood too acidic. This can lead to severe dehydration and is a medical emergency. It's very different from the mild ketosis that happens with a low-carb diet.
Scientists are studying ketosis for its potential benefits. For example, they are looking at how it might help with brain conditions like Alzheimer's disease. They are also researching its effects in children with Angelman syndrome.
See also
- Fatty acid metabolism
