Top 6 Foods to Block DHT and Prevent Hair Loss. Dihydrotestosterone (DHT) is a hormone similar to testosterone, which helps grow body hair during puberty. However, high DHT levels can cause hair loss. Your body converts about 10% of testosterone into DHT with the help of an enzyme called 5-alpha reductase. Some foods might block this enzyme, reducing DHT and potentially preventing hair loss. Here are six such foods.