energy and nutrient Influencing factors

 

For some food groups, the concept of this definition of nutrient density can also be applied in an easily understandable form. These include, for example, fresh vegetables, fresh fruit, fresh herbs, or fresh mushrooms. In practice, however, we encounter other influencing factors that make this classification of foods difficult. 

Different calorie needs

The recommendation to give preference to foods with a high nutrient density, by definition, focuses on low-calorie foods. However, not all want, need, or have to restrict their calorie intake, so that a fair evaluation of foods with a high calorie and high nutrient content (e.g., nuts, seeds) should also be permissible. It is a necessity, especially concerning diseases that require a lot of energy.

Desired and unwanted nutrients

For some of the primary nutrients, such as fats, some fractions can be assessed differently in terms of quality. Dietary fats contain saturated, monounsaturated, and polyunsaturated fatty acids. The latter can also be divided into omega-3 fatty acids and omega-6 fatty acids. While saturated fatty acids are sufficiently absorbed through food, omega-3 fatty acids are found in far fewer foods and require special attention. These should be taken into justification in the definition of nutrient density. 

On the other hand, some foods contain both recommended and less recommended nutrients. For example, Meat contains many essential amino acids and less desirable purines and inflammation-promoting omega-6 fatty acids. Here a more differentiated Meat view would be alluring, but again too complicated for practice. That could be taken to extremes if the content of omega-3 fatty acids in Meat from factory farming and Meat from grazing animals were included in a possible assessment.

Different portion sizes

As a rule, less than 100 g of herbs are consumed. If we convert the average nutrient content to portion size, the energy content is still shallow. But the nutrient content is also significantly lower. Therefore, vitamins and minerals, herbs, and spices only play a subordinate role. It also applies to the desired amounts of fiber, unsaturated fatty acids, or essential amino acids. Nevertheless, herbs and spices are valuable and recommendable due to other ingredients (e.g., secondary plant substances), which are only required in tiny quantities. 

In turn, we consume significantly more than 100 g of other foods. An average frozen pizza weighs between 380 and 400 g. This portion's energy content is then assessed as very high, with the nutrient content being relatively moderate. Most pizzas are abundant in carbohydrates and poor-quality fats. The fiber, vitamins, and minerals content are usually low, depending on the chosen topping. So if we take a targeted look at the desired nutrients, the average pizza does rather poorly.

Degree of processing and preparation

An apple has many nutrients per 100 g with relatively few calories and sugar and has a rather high nutrient density. On the other hand, Apple juice has fewer nutrients per 100 g with more calories and more sugar. The nutrient density here could be described as moderate. Applesauce probably has even fewer nutrients per 100 g with even more calories and sugar and has a relatively low nutrient density. However, if the nutrient sugar is included in the nutrient density, applesauce and apple juice may fare better than apples. The degree of preparation and processing also plays a role.

There is also trickery in the case of children's foods such as breakfast cereals. Here, sugar is often added in considerable quantities. It does not provide any other nutrients besides calories. However, by adding vitamins, the nutrient content is artificially increased. IT means that the nutrient density is higher. The food is still relatively not recommended. 

Different bioavailability of nutrients and interactions

The concept does not take into account the different availability of nutrients. Green vegetables are rich in iron. However, this is poorly absorbed by the body. On the other hand, animal iron sources are more readily available to the human body.

The same applies to fat-soluble vitamins: The body only sufficiently absorbs these in the presence of fat. An evaluation of foods based on the nutrient density can lead to incorrect results since low-fat (and therefore lower-energy) foods perform better than high-fat (and therefore higher-energy) foods.

Another practical example is that of the green smoothies. These consist of leaves, fruits, and various types of vegetables. This means that green smoothies have a very high nutrient density because the energy content is relatively low. But some vegetables and herbs contain substances such as oxalic acid, which inhibit the absorption of numerous vitamins. They hurt the nutrient density, but it can hardly be calculated. 

Other influences

The list of influencing factors could probably be continued indefinitely. In the case of plant-based foods, for example, the weather, the variety used for cultivation, the nature of the soil, the use of fertilizers and pesticides, and the time of harvest, storage, and transport all affect the nutrient content. On the other hand, in animal products, the age of the animals, housing conditions, feed, pharmaceuticals, or processing are essential factors influencing the content of various nutrients.

Ultimately, the nutrient density is usually determined for a single food. However, we rarely eat just one food but combine several for one meal. At this point, working with nutrient density becomes too complicated and impractical.