There is no evidence that eating a specific food will increase T-cells. However, an adequate nutrient-dense diet does provide the building blocks for immune cells. Certain nutrients (e.g., beta carotene) in foods have been shown to improve T-cells but at much larger doses than is usually found in food. There are some theories about the potential benefits of coconut and garlic, but the claims for these foods have not been adequately studied, much less proven.