All the necessary stuffs contained in natural foods we eat. If your diet is correct and various, then all the desired substances can be obtained from food.
There are 8 vitamins and supplements are important for healthy life.
Modern man eats far from the way people ate before. The modern products often contains almost no vitamins. Proteins, fats and carbohydrates (and not the best quality) that's all that our body can extract useful from these products. As for fresh vegetables and fruits, their content of vitamins and especially minerals directly depends on the conditions in which they were grown.
If the soil is poor in minerals - in plants these substances would be too little. If the growth and maturation of fruits and vegetables was artificially accelerated, they will not have time to accumulate enough minerals, even on the mineral-rich soil. Transportation and storage with use of antibiotics, radiation, preservatives, and just refrigerators, destroys most of the vitamins. As a result, there is no way to get the vitamins and minerals from food in the right quantity and you need to take vitamin and mineral supplements.