How Salivary Amylase Aids Digestion?

While one may believe that the digestion of food happens in the stomach, it’s not the case. The digestion process starts as soon as we take our first bite or sip. Salivary enzymes play a pivotal role in the breakdown of food while we’re still chewing. And depending upon the reactions they help catalyse, they can be categorised as salivary amylase, salivary protease, and salivary lipase. Read through to know more about the role of salivary amylase.

What is Salivary Amylase?

Salivary amylase is a digestive enzyme produced by the salivary gland. Its secretion in the saliva starts as soon as a food piece or drink goes into the mouth. The salivary amylase aids in digestion as it helps break down the food while the saliva moistens the mouth. The salivary amylase helps digest the starch and carbohydrates. It helps in the breakdown of complex carbohydrates into sugars, which the body can absorb easily.

Likewise, the salivary protease helps in the breakdown of proteins and salivary lipase is responsible for the breakdown of fats into glycerol and fatty acids.

Salivary Amylase and Digestion

Enzymes play a pivotal role in the digestion of foods. Salivary amylase helps catalyse the carbohydrates present in the food into simple sugar. During the digestion process, amylose and amylopectin, the complex carbohydrates present in the food, are broken down into maltose, the body’s primary source of energy. Complex carbohydrates are partially hydrolysed in mouth by salivary amylase

This chemical reaction in the body promotes digestion and absorption of energy from the food. Thus, healthy digestion is required for a healthy body.

Link Between Salivary Amylase and Obesity

Research suggests that people with low salivary amylase expression have a higher Body Mass Index (BMI) and therefore are obese or overweight. Low levels also lead to glucose mal-absorption. This lowers the ability to digest and use complex carbohydrates to generate energy.

However, it’s not known whether obesity lowers the expression of the salivary amylase or a decrease in its levels fuels obesity. But the imbalance affects each other in a vicious circle.

Link Between Salivary Amylase and Weight Loss

On the other hand, a high expression of salivary amylase in the body is associated with weight loss. Research shows that people with higher levels of amylase in their bodies tend to lose weight faster than counterparts who have normal or low levels of amylase. 

A higher salivary amylase activity increases glucose tolerance after the consumption of starch. It decreases insulin resistance, metabolic syndrome, and type 2 diabetes.

Normal Range of Salivary Amylase

Not everyone produces the same levels of salivary amylase. Some may produce high levels, while others may be deficient. Both conditions will affect the breakdown of food and its absorption. The levels of amylase in the blood can be tested through a blood or urine test. The normal range of the amylase in the blood or urine is between 28 and 100 U/dl. The report may either show a normal value or have an increased/decreased level. The implications of each are as follows:

1. Higher than Normal Levels

Hyperamylasemia is a medical condition wherein the levels of amylase in the blood or urine increase beyond the normal levels. The condition may be categorised as:

1. Mild hyperamylasemia (100 – 150 U/dl)
2. Moderate hyperamylasemia (150 – 200 U/dl)
3. Marked hyperamylasemia (200 – 500 U/dl)
4. Severe hyperamylasemia (> 500 U/dl)

Factors that lead to hyperamylasemia are alcohol; pregnancy; burns; and drugs like Antineoplastics, oral contraceptives, Antihypertensives, antihistamines, Antituberculars, Aspirin, Iodinated contrast, Diuretics, and Opiate.

Hyperamylasemia may hint toward the following medical conditions:

1. Acute pancreatitis (inflammation of the pancreas)
2. Pancreatic cancer or blockage in the bile duct
3. Cancer of the ovaries
4. Lung cancer
5. Cholecystitis (inflammation of the gallbladder)
6. Infection of the salivary glands (mumps)
7. Intestinal blockage
8. Ulcer
9. Kidney failure
10. Peptic ulcer
11. Gastroenteritis
12. Ectopic pregnancy 
13. Viral hepatitis
14. HIV
15. Cystic Fibrosis

To lower the levels of salivary amylase in the blood, you should follow a low-fat diet. Cut down on the consumption of red meat and sausages and go high on fibre derived from fruits and vegetables. People with Hyperamylasemia must abstain from alcohol.

2. Lower Than Normal Levels

Hyperamylasemia is a medical condition wherein the levels of amylase in the blood or urine fall below the normal levels. The condition may be categorised as Mild Hypoamylasemia (0 – 28 U/dl in adults). The factors that lead to Hypoamylasemia are obesity and drugs like antibiotics, anticoagulants, and citrates.

Hypoamylasemia may hint toward the following medical conditions:

1. Type 1 diabetes
2. Type 2 diabetes
3. Diabetes mellitus
4. Metabolic syndrome
5. Fatty liver
6. Cystic fibrosis

To increase the levels of amylase in the blood, try losing weight and reduce the intake of carbohydrates.

Conclusion

Amylase is a digestive enzyme that helps in the breakdown of starch and carbohydrates. The amylase secreted by the salivary gland is called salivary amylase. The primary role of the salivary amylase is to start the digestion process in the mouth as it breaks down carbohydrates into simple sugar. But medical conditions and a range of factors can lead to the improper secretion of the enzyme. This in turn affects the digestion process, leading to unexplained weight loss or weight gain. Thankfully, a diagnosis of the condition is possible through simple blood and urine tests.