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Essential Nutrients, Recommended Dietary Allowances (RDA), Adequate Intakes (AI) and Dietary Reference Intakes (DRI)

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What are essential nutrients? 

The list of nutrients includes hundreds of substances and list seems to keep getting longer. However, not all of the nutrients are deemed essential. Essential nutrients are those nutrients that are absolutely vital and are not made in the body either at all or in sufficient quantities to meet our needs. These essential nutrients must be in the foods we eat (or supplemented) and in sufficient quantities otherwise signs of deficiency can develop over time.

Essential nutrients can be grouped together based on general similarities such as those that provide energy (carbohydrates, proteins, fats), vitamins, minerals, and water (see Table below).

Click to see larger Nutrition Facts Panel

We can reinforce our understanding of the difference between nutrients and essential nutrients with a couple of examples. Glycine is an amino acid, which is absolutely necessary to make proteins in our cells. We have the ability to make ample glycine and therefore, theoretically, it does not need to be part of our diet. However, our body will gladly put the glycine we eat to work, so it is indeed a nutrient; it is just not considered an essential nutrient. Said another way, if glycine was lacking from our diet, it is unlikely that deficiency signs would develop because we can make plenty of it in our body. 


Essential Nutrients Classes

Energy Nutrients




Protein/Essential Amino Acids, Carbohydrates, Fat

Vitamins A, C, D, E, K and B6, B12 Thiamin, Folate, Biotin, Niacin, Riboflavin, Thiamin, Pantothenic acid, Choline

Calcium, Zinc, Copper, Sodium, Potassium, Iron, Phosphorus, Magnesium, Chromium, Chloride, Molybdenum, Fluoride, Selenium Manganese, Iodide, Chromium



What are the RDAs and DRIs? 

If our diet fails to consistently provide adequate amounts of an essential nutrient, over time signs of deficiency will result. To address this notion, the first Recommended Dietary Allowances (RDAs) were developed by the United States government in the early 1940s. Other countries have similar recommendations. Recently, US and Canadian scientists pooled their resources to modify developed a more detailed set of nutrition recommendations collectively called the Dietary Reference Intakes or DRIs (see DRI Table). The DRIs include the RDAs, which speak more to preventing deficiency and promoting normal growth, development and normal health for most people as well as other applications such as average requirements and toxicity levels.TheDRIs are periodically scrutinized and revised based on the most current research findings.


How are the RDAs and DRIs determined?

If an essential nutrient has enough research to allow for more specific recommendations to be made, then the recommendation level is called an RDA. Simply put, an RDA is the average daily level of nutrient needed to prevent deficiency and promote general well being for about 98% of a specific gender, age and condition. See hypothetical Balance Graphs and setting the RDA.

On the other hand, for some nutrients such as vitamin D and calcium, an Adequate Intake (AI) level is listed instead of RDA.


Like RDAs, AIs are also recommendations for a given nutrient, however there is not was not enough of a certain type of scientific information to designate a RDA quantity. Thus difference between a RDA and an AI is mostly the type and level of research studies that can be applied to the nutritional needs of a particular nutrient. A RDA is set when research allows for a more detailed understanding of how much of a nutrient is particular nutrient is needed to prevent deficiency and promote general health. Meanwhile, AIs tend to be based more on studies of large populations of people and an observed level of intake of that nutrient that is associated with general health and no deficiency.

Currently there are RDAs and/or AI for vitamins A, D, E, K and C, thiamin (B1), riboflavin (B2), niacin (B3), pyridoxine (B6), cobalamin (B12), folate, biotin and pantothenic acid as well as calcium, phosphorus, magnesium, iron, zinc, iodine, selenium, copper, manganese, fluoride, chromium, and molybdenum. Meanwhile, sodium, potassium, and chloride have Estimated Minimum Requirements. These elements are found in most foods, either naturally or after processing, and are extremely well absorbed into the body after we eat them. Therefore, a deficiency in any of these essential nutrients is unlikely, providing there are no confounding factors. 


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