How Much of the Essential Nutrients Do We Need?

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 develop a more detailed set of nutrition recommendations collectively called the Dietary Reference Intakes or DRIs (Tables 3.2a–e). 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.

The DRIs are periodically scrutinized and revised based on the most current research findings. 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 to promote general well-being for about 98 percent of a specific gender, age, and condition. On the other hand, for some nutrients such as vitamin D and calcium, an Adequate Intake (AI) level is listed instead of RDA.

An RDA is the level of an essential nutrient determined to be adequate for most people to prevent deficiency and to support well-being. Like RDAs, AIs are also recommendations for a given nutrient, however there is 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. An RDA is set when research allows for a more detailed understanding of how much of a 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. Sodium, potassium, and chloride also have AI levels. 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.