Nutrient Density

The term "nutrient density" refers to the proportion of micronutrients found within a particular food in comparison to that food’s overall calories. Sometimes described as being nutrient rich or micronutrient dense, nutrient-dense foods are typically considered to be the healthier counterpart of energy-rich or nutrient-poor foods, which are those containing a significant amount of calories but a correspondingly low proportion of nutrients. Foods typically considered nutrient dense include leafy greens such as spinach, fish such as salmon, and whole-grain products such as whole-wheat flour or cereal. Nutrient density is particularly important in light of the serious ramifications of nutrient deficiency. Among the essential nutrients found in many nutrient-dense foods are iron, iodine, and vitamin A, deficiencies of which can cause major health problems. In light of such risks, some food manufacturers add essential micronutrients to certain foods, thus improving their nutrient density through a process known as "fortification."

Background

In general, nutrients are categorized as macronutrients and micronutrients. Macronutrients include fats, carbohydrates, and proteins. Such nutrients, which are typically consumed in relatively large quantities, supply energy to the body and play essential roles in the body’s regular functions: carbohydrates are a primary fuel source for the body, fats help maintain normal growth, and proteins are essential to building muscles. Micronutrients, on the other hand, are consumed in much smaller amounts but are no less essential. Generally, such nutrients are categorized as vitamins or minerals. Some of the minerals most crucial to the body’s functions include calcium, iodine, iron, potassium, and zinc, while similarly essential vitamins include folate (also known as vitamin B₉ or folic acid) and vitamins A, C, and D, among others.

Micronutrients are especially important to the human diet because a lack of certain nutrients can cause serious health problems. A deficiency of iron, for example, can cause anemia, which can be detrimental to growth and development in children and can cause severe fatigue and weakness in adults. Vitamin A deficiency can cause severe visual impairment and is one of the leading causes of blindness among children. Because of the serious nature of these issues, health-focused groups such as the World Health Organization (WHO) have made efforts to combat such nutrient deficiencies in the areas where they are endemic. This is accomplished in large part through education and outreach programs—such as those promoting breastfeeding, which passes numerous essential macronutrients and micronutrients from mother to child—among pregnant women and new mothers. Other efforts to reduce eliminate nutrient deficiencies have focused on adding essential micronutrients to the less-nutritious foods available to many vulnerable populations, thus rendering such foods more nutrient dense.

Overview

Nutrient density has long been the subject of significant study, as scientists and organizations such as the WHO have sought to improve the diets and overall health of populations worldwide. However, such experts have at times faced difficulties in quantifying nutrient density. In general, foods considered nutrient dense have a high percentage of micronutrients in relation to their calories per serving. While this definition provides a basic understanding of the concept, some scientists have attempted to develop simplified means of expressing a food’s nutrient density, such as through a numerical score. Various experts and organizations have introduced their own systems of quantifying nutrient density, but none has yet to be conclusively proven more accurate or useful than the others.

Although individual scientists, organizations, and government bodies frequently disagree on which foods should be considered nutrient dense, numerous foods are widely considered to fall within that category due to their high micronutrient values and relatively low caloric content. Many vegetables are generally considered nutrient dense, as they frequently contain high proportions of vitamins and minerals. Nutrient-dense vegetables include broccoli, carrots, and leafy greens such as spinach, kale, and collard greens. Fruits such as strawberries and oranges are considered relatively nutrient dense, as are many legumes and nuts. Fish, poultry, and other lean meats are likewise major sources of various nutrients, particularly iron and zinc, as are low-fat dairy products. Whole grains are likewise considered nutrient dense by many experts.

Generally, foods that are highly processed are less nutrient dense than their unprocessed or minimally processed counterparts. This is because some of the processes these foods undergo can strip certain nutrients from the food. For example, white flour has fewer micronutrients than whole-wheat flour because the former is made from only the endosperm, or innermost part, of the wheat berry. Whole-wheat flour, on the other hand, retains the outer bran and germ of the wheat berry, which contain much of wheat’s iron and other vitamins and minerals. Cooking processes can also reduce the nutrient density of foods. Boiling vegetables, for instance, can decrease the levels of some vitamins, as certain vitamins are water soluble—that is, capable of dissolving in water. However, some cooking methods can increase the bioavailability—ability to be absorbed by the body—of certain nutrients. Thus, an individual seeking to maximize his or her micronutrient intake should evaluate cooking methods on a case-by-case basis.

Some foods are fortified to improve their nutritional value. Fortification is the process of adding micronutrients to foods, thereby increasing their nutrient density and ensuring that populations who may not ordinarily consume enough of certain micronutrients have the opportunity to do so. Table salt, for instance, is frequently fortified with iodine to reduce the risk of iodine deficiency, which can impair cognitive function. As white flour loses much of its iron in the manufacturing process, it is often fortified with that mineral, a process known as "enrichment." Although fortification is often beneficial, it does present some health risks, as individuals who consume too many fortified foods could potentially consume dangerous levels of micronutrients. Just as a deficiency of micronutrients can cause a variety of serious health problems, an excess can be harmful as well, leading at times to medical issues such as organ damage.

Bibliography

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