It shouldn’t be news to you that orange juice is packed with vitamin C. Vitamin C is also known as ascorbic acid, and it can block a key enzyme called alpha-amylase that breaks down starch into easily digestible sugars for your body to use as energy. This could slow down a spike in blood sugar in people who have diabetes. A 2016 article in the Biomedical and Pharmacology Journal found that people with type 1 diabetes have higher levels of salivary alpha-amylase than non-diabetic people. Supplementing with 500 to 1,000 milligrams of vitamin C could help control blood sugar and high blood pressure in people with type 2 diabetes, according to a 2023 review in Free Radical Biology and Medicine.
However, you don’t want to be loading up on orange juice or ascorbic acid supplements so that your body doesn’t digest starches. You need alpha-amylase produced by your salivary glands and pancreas to keep your digestive system working properly. Not enough of this digestive enzyme could cause diarrhea due to the undigested carbs sitting in your intestines, according to Johns Hopkins Medicine.