Yes they are ...
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Blueberries (one 148g serving) contain more nutrients per gram than most foods out there.
They are a source of Vitamin C, Vitamin K, and Folate. These flavonoids have strong antioxidant properties with many health benefits.
One cup of fresh, whole blueberries contain 24% of daily recommended levels of vitamin-C. Vitamin-C is a moderately powerful antioxidant, which may help the human body develop resistance against infectious agents and attack the harmful oxygen free radicals.
Blueberries are also an source of Vitamin K; 148 g of blueberries provide 36% of the RDA. Vitamin K, a great antioxidant, is required for blood clotting and building healthy bones.
Antioxidants such as the ones found in blueberries are said to be essential for boosting immunity. Some of these may play an important role in helping improve your immune system to fight off flu and other viruses.
Eat and be healthy.
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