Science project

How Does Diet Affect Your pH?

Research Questions:

  • Can diet change pH?
  • Which foods can change the pH of my body?

The foods that you eat affect your body in many different ways. Certain “acidifying” diets are believed to lower the pH of your body, while “alkalizing” diets may raise your pH. The objective of this experiment is to learn about chemical balances within the human body by evaluating if/how minor diet modifications alter the pH of your saliva.


  • pH test strips
  • Either alkalizing or acidifying foods (dependent on the diet plan that you select)
  • Notebook for recording and analyzing results

Experimental Procedure:

  1. Keep a diary of your food intake for a week. During this week also analyze and record the pH of your saliva three times each day (eg, morning, noon and before bed).
  2. Research acidifying and alkalizing diets. Evaluate which type of diet you tend to follow. For example, acidifying foods include cranberries, prunes, grains, and beans. Alkalizing foods include almonds, milk, cottage cheese, and eggs.
  3. Select a diet to follow for approximately three weeks. If you usually eat a more acidifying diet, then follow an alkalizing diet. If you tend to follow a more alkalizing diet, then switch to an acidifying diet.
  4. Analyze and record the pH of your saliva three times each day for the duration of the experiment.
  5. Analyze you results. Do you notice changes in your pH after beginning your new diet? How quickly do changes take place? Does you pH return to its starting level when you stop the diet?

Terms/Concepts: pH, body chemistry, alkalizing diet, acidifying diet

References: “pH Balancing Foods.”

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