Differences between vegetables
When formulating a diet for an animal, it is important that vegetables are used that meet the needs of the animal. The definition of vegetables is: 'all edible parts of plants that are not fruits or seeds'. This broad definition ensures that vegetables have very diverse nutritional values. Vegetables can be divided into four categories: leafy vegetables, root vegetables, fruit vegetables and other vegetables. The last two categories are occasionally also grouped together as watery vegetables. Table 1 shows examples of the four categories with associated vegetables. The nutritional differences per category are explained below, supported by various bar charts from table 2.
Table 1. Different vegetables divided over four categories
Leaves are the parts of plants where most photosynthesis takes place. As a result, these are the parts of the plant that often contain the most nutrients. For example, leafy vegetables are often rich in vitamins and minerals. In addition, leafy vegetables are one of the few natural sources of folic acid (vitamin B11), which is important for the production of red blood cells and the proper functioning of the nerves. Leafy greens are low in available carbohydrates but relatively high in protein, fat and fibre. Table 2 shows the nutritional values of some leafy vegetables.
Based on their properties, root vegetables can be divided into true roots or modified stems. Sweet potato, carrots and cassava are examples of true roots. While potatoes, radishes and beets are examples of modified stems. Root vegetables mainly grow below soil and function as a storage space for starch. As a result, they often also contain a high content of fibre and available carbohydrates, which mainly consist of starches instead of sugars. On the other hand, the amount of water is also on the lower side. Table 2 shows the nutritional values of some root vegetables.
Fruit vegetables include tomatoes, bell peppers and cucumbers. These are all characterized by having a fleshy and seed-rich texture. Fruit vegetables are relatively low in protein, fat, fibre, available carbohydrates and minerals. However, they contain a relatively high amount of water and vitamins. The available carbohydrates in fruit vegetables mainly consist of sugars and hardly any starch, which means that the total amount of sugar is also relatively high. Table 2 shows the nutritional values of some fruit vegetables.
As the name suggests, the other vegetables category is suitable for vegetables that are more difficult to place in one of the other three categories. Because this category is quite diverse, it is more difficult to make general statements. A remarkable feature of many of these vegetables is that they mainly consist of a stem. These vegetables also often contain a higher content of proteins, fibers and vitamins. On the other hand, the amount of available carbohydrates is often lower. Table 2 shows the nutritional values of some vegetables within this category.
*Graphs are based on the average values of the different categories in table 2*
Table 2. Nutritional composition of different vegetables divided over four categories
Source: Food composition and nutrition tables, Souci, Fachmann and Kraut, 7th revised and completed edition