Hazelnuts are the fruit of the hazel shrub and grow mainly in the northern hemisphere. Hazelnuts contain a lot of fat and thus many calories, but the nuts are very healthy! The fats contained therein are unsaturated fatty acids and so-called "healthy fats". Similarly, large amounts of vitamin E, several B vitamins, magnesium, phosphorus, potassium, iron and calcium, and fiber are present in the healthy nuts.