Image by Alto Images / Stocksy May 31, 2026 An essential vitamin with secret superpowers, vitamin C does more than it's famed for. Found in citrus fruits, berries, peppers, and other plant foods, vitamin C provides your brain with the support it needs for optimal memory, cognitive function, and mood regulation.* It seems like vitamin C is the original trendy vitamin that was quickly overlooked when research about vitamin D and other essential nutrients came out.