Blood tests for vitamin C and plant pigments stay accurate even after years in storage, making them trustworthy tools to measure how much fruit and vegetables people eat over time.

People with more vitamin C in their blood — which comes from eating fruits and vegetables — are less likely to get type 2 diabetes, even after accounting for other healthy habits.

People who eat about 66 grams more fruits and vegetables each day — roughly one extra apple or a cup of carrots — have a 25% lower chance of getting type 2 diabetes, according to blood tests that measure plant nutrients.

When people who don't eat much fruit or veggies start eating about 8 servings a day for 3 months, the level of vitamin C in their blood goes up by 35%, meaning their body gets more of this important nutrient.