Human kind has depended on a variety of crops to fulfill their alimentary needs. Through history, the differences in geographical characteristics have provided human kind with a variety of plants to eat. Different crops have grown in different geographical areas due to difference in climate, topography and precipitation patterns (Leff et al. 2004). After humans learned and developed domestication of alimentary crops, the variety of such crops has diversified and spread beyond their natural range. Since the domestication of important crops, human kind has been favored with commercial exchange of crops increasing their diet and obtaining the benefits of plants nutritional value (George Metljan Foundation 2008). .
A varied diet includes cereals, vegetables, legumes fruits and products of animal source. Although in some areas of the world due to scarce meat availability or due to religious reasons, some people do not include animal proteins. In such cases legumes become the main source of protein in their diet (Friedman 1996 and Leff et al. 2004). Thus, the main objective of this literature review is to highlight the geographical distribution of some important crops of cereals, legumes, vegetables and fruits; as well to stress out their nutritional value to humans. .
The selected crops for cereals include: rice, oats and wheat. In the case of the legumes the listed crops are: lentils, beans and chickpeas. For vegetable crops, the included ones are: broccoli, onion and spinach. The selected fruits to be discussed include: avocado, apple and cranberries. It is expected that with this literature review, the reader is able to realize the nutritional value of a varied diet; as well to provide the reader with important facts of each cereal, legume, vegetable and fruit to be discussed. .
Cereals.
The cereal crops are a vital part of human diet, and their variety began in Eastern and South Eurasia.