One of the ways certain health products get marketed is by claiming that they make your body more alkaline (as opposed to acidic). Here's the deal. Your body maintains a tightly controlled pH level within the range of 7.35 and 7.45... always. If it didn't, you'd be dead. Nothing you ingest is going to make you more alkaline, so any product claiming to do so is being disingenuous.
There is something to keep in mind, however. Most of the food you eat will either be more acidic or more alkaline than your body's pH level. This isn't an immediate problem. Your body has buffering systems that counteract the pH level of the foods we eat to maintain the body's overall level. In order to neutralize acidic foods the body's phosphate buffer system uses calcium from the bones, which can weaken them over time if your diet is overly acidic. The calcium is then excreted through the urinary system which can lead to an increased risk of developing kidney stones.
Meat, dairy, sugar, and grains are acidic foods. Fruits and vegetables are alkaline. Your long-term health is best served by a diet that balances the foods from these two groups.