Nuts and seeds—among the most celebrated heart-healthy foods—promote smooth, steady blood flow, which is critical for keeping your memory sharp. Their nutrient claim to fame? Unsaturated fats, which help to improve cholesterol levels and ease inflammation, ensuring a continuous supply of oxygen and nutrients to your think tank. Swap your 3 p.m. candy bar for a handful of almonds, cashews, pistachios or seeds (try sunflower or pumpkin) and you’ll be well-fueled to tackle your afternoon workload.