This has its basis in truth, because fresh fruit, including fresh fruit juice is quicker to digest than most other whole foods. Therefore mixing fruit with other foods such as grains or meats can cause indigestion somewhere along the digestive tract if eaten together. This depends on your ability to digest. If you are prone to variable appetite, gas or bloating(vata tendencies) or simply not hungry when you sit down to your meal, eating fruit with or after your food will undoubtedly leave you with some symptoms. Since the sweet taste is important to gain satisfaction from a meal, and fruits are a natural source, try eating the fruit or drinking the juice before the rest of the food. This will alleviate any potential indigestion.