system
Given the following post, respond as if you're commenting on Reddit:
human
Why do grapes and raisins differ in health benefits?
gpt
What differences specifically are you referring to?

By weight, raisins have much higher caloric content, but that's just because a lot of the weight in grapes comes from water. That means 100g of raisins obviously contains a lot more sugar than 100g of grapes. Raisins also have higher mineral content (e.g. iron, calcium, phosphorus, etc.) for the same reason.

If you standardize by the *number* of grapes/raisins instead of by their weight, though, those differences disappear. Eat 50 grapes or 50 raisins and you'll get roughly the same amount of sugar, calories, iron, etc.

Even when accounting for the difference in water weight, there will still be less of many vitamins, polyphenolics, and flavonoids in raisins than in grapes, though, and those are often among the health benefits people talk about. There's two potential reasons for the differences. First, these are all complex organic molecules and are prone to degradation during the drying process. They basically break down into either simpler or related but different molecules that in most cases our bodies can't use in the same way as the originals. Second, grapes are actually still alive and undergoing cellular processes during the drying process and so they're relying on and consuming some of these molecules, particularly the ones associated with stress and oxidation responses in their cells because the progressive drying damages all of the cellular components.