All types of mushrooms are rich in vitamin B3. Shiitake mushrooms are the best with 100 grams serving providing 14.1 mg or 71% DV of niacin. They also possess anti-cancer properties. A 100 grams serving of grilled Portobello provides 6.3 mg or 31% DV of vitamin B3. Other mushrooms that contain significant amounts of niacin include cooked white mushroom (35% DV), raw oyster (21% DV), raw brown mushroom (14% DV) and raw chanterelle (11% DV).
Among the fruits, avocado is a good source of vitamin B3. A single avocado provides 3.5 mg or 17% DV of niacin. However, it should be consumed in moderation as it is also high in calories. Just half an avocado contains 160 calories.