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Effect of PH on Digestion

author image Jessica Bruso
Based in Massachusetts, Jessica Bruso has been writing since 2008. She holds a master of science degree in food policy and applied nutrition and a bachelor of arts degree in international relations, both from Tufts University.
Effect of PH on Digestion
Different pH levels facilitate digestion of food through enzymes. Photo Credit meat image by Svetlana Kashkina from <a href="http://www.fotolia.com">Fotolia.com</a>

How acid or how alkaline your digestive system is can affect how well your food is digested. This is measured using the pH scale, with lower numbers indicating an acid environment and higher numbers indicating an alkaline environment. Not all parts of your digestive tract have the same pH because different stages of the digestive process require different levels of acidity.

Digestive Process

Digestion is the process of breaking down the food you eat into components that are small enough for your body to absorb. The process starts with your teeth and saliva, then after you swallow, the food passes down your esophagus and into your stomach, where enzymes break down the food further. Digestion and the absorption of nutrients continue in the intestines, using enzymes made in the liver, gallbladder and pancreas.

Enzymes and pH

Enzymes are a type of protein that cause chemical reactions, such as the breakdown of carbohydrates into glucose, protein into amino acids and fat into fatty acids and glycerol. Different enzymes are more effective at different pH levels. If the pH levels are too high or too low for a particular enzyme, it might get denatured and will no longer perform its function.

Digestive System pH Levels

Components in saliva help keep the pH in your mouth between 6.5 and 7 so that the enzyme salivary amylase can start to break down carbohydrates. The enzymes that help digest food in the stomach, such as pepsin, work best at a pH around 2, while those that function in the intestines, including peptidases and maltase, work best at a pH around 7.5.


Antacids increase the pH in the stomach, which might make the enzymes in the stomach less effective. The low pH of the juices in the stomach can cause ulcers if they eat through the walls of the small intestine or stomach. This low pH also kills many microorganisms in the food you eat, helping prevent illnesses.

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