Understanding the Dietary Reference Intakes (DRIs)
The Dietary Reference Intakes (DRIs) are a set of nutrient reference values for healthy individuals established by the Food and Nutrition Board of the National Academies and Health Canada. These values guide nutrient intake for different life stages and genders. The DRIs include:
- Estimated Average Requirement (EAR): Average daily intake for half of healthy individuals in a group.
- Recommended Dietary Allowance (RDA): Sufficient intake for nearly all (97–98%) healthy people in a group, calculated from the EAR.
- Adequate Intake (AI): Used when there isn't enough data for an EAR and RDA. Based on approximations of nutrient intake by healthy individuals.
- Tolerable Upper Intake Level (UL): Maximum daily intake unlikely to cause adverse effects.
The Necessity of Adequate Intake (AI)
Establishing an RDA requires substantial scientific evidence, including controlled studies, to determine the EAR. When evidence is lacking, an expert judgment is made to set an Adequate Intake (AI) based on available data. For infants, the AI is based on average nutrient intake from human milk. For others, AIs may be based on population intake estimates or limited studies.
How Adequate Intake (AI) is Derived
Setting an AI relies more on qualitative observations and expert judgment than on the statistical analysis used for RDAs. Methods vary. Approaches include observed mean intake of healthy individuals, experimental approximations, and human milk intake for infants. For example, the AI for vitamin K was based on survey data, and choline's AI used experimental data.
AI vs. RDA: A Comparison
| Feature | Adequate Intake (AI) | Recommended Dietary Allowance (RDA) |
|---|---|---|
| Basis | Based on approximations of nutrient intake by healthy groups or experimental data. | Calculated statistically from the Estimated Average Requirement (EAR), based on strong scientific evidence. |
| Certainty | Less certain than the RDA; requires more judgment. | Represents a high degree of confidence it meets needs of almost all healthy people. |
| Uses for Individuals | Serves as a target goal for individual intake. | Serves as a target goal for individual intake. |
| Uses for Groups | Can indicate a low prevalence of inadequacy if mean intake is at or above the AI, but cannot assess inadequacy prevalence if intake is below the AI. | Can assess group adequacy based on EAR, but RDA itself should not be used as a cut-point. |
| Statistical Relationship | Does not have a consistent statistical relationship to the EAR. | Statistically derived from the EAR, typically at 2 standard deviations above EAR. |
Practical Implications for Dietary Planning
For individuals, the AI is a reliable target when an RDA isn't available. Meeting or exceeding the AI suggests adequate intake. Intake below the AI doesn't necessarily mean inadequacy and cannot be used to quantify risk. Instead, it highlights the need for more information and potentially a look at the overall diet. AI values are included in nutrition education. For public health, the AI is used to assess group intakes, but cannot determine the specific prevalence of inadequacy as the EAR is needed for that.
Conclusion
The Adequate Intake (AI) is a crucial part of nutrition guidance, providing benchmarks when data for an RDA is not available. It assures that dietary targets are based on the best possible approximations. The AI allows for guidance even with incomplete research, and as evidence grows, some AIs may become RDAs. Using AIs alongside other DRIs supports informed nutritional decisions.
What does it mean when there is not enough adequate information to establish a recommended dietary allowance (RDA) for a nutrient?
When there isn't enough robust scientific data, like a clear Estimated Average Requirement (EAR), to determine a specific value that meets the needs of 97–98% of the healthy population, an RDA cannot be established.
What is assigned instead of an RDA when there is insufficient evidence?
An Adequate Intake (AI) is assigned when there is insufficient scientific evidence to establish an RDA. {Link: ScienceDirect Topics https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/adequate-intake}.
How is an Adequate Intake (AI) value determined?
An AI is determined based on the best available information, which may include observing the average nutrient intake of healthy individuals or estimations from experimental studies. The AI for infants is based on human milk intake.
Can I use the Adequate Intake (AI) as a target for my daily nutrient intake?
Yes, the AI is intended to be used as a goal for individual nutrient intake. If your usual intake meets or exceeds the AI, there is a low likelihood of nutritional inadequacy.
What if my nutrient intake falls below the Adequate Intake (AI)?
If your intake is below the AI, it is not necessarily inadequate. However, it may suggest a need for further evaluation with a healthcare professional, especially if other indicators of nutritional status are a concern.
Is the Adequate Intake (AI) used for assessing population health?
For groups, if the mean intake is at or above the AI, it suggests a low prevalence of inadequacy. However, unlike the EAR, the AI cannot be used to determine the specific prevalence of inadequate intakes when the mean is below the AI.
Who establishes the Dietary Reference Intakes, including the Adequate Intake (AI)?
The Dietary Reference Intakes (DRIs), which include the AI, are established by the Food and Nutrition Board of the National Academies and Health Canada.
Conclusion
Dietary guidelines are dynamic, reflecting current evidence. The Adequate Intake (AI) serves as a valuable benchmark for nutrients lacking the data to establish an RDA. It assures consumers that dietary targets are based on the best available approximations. Using AIs alongside other dietary reference values allows for informed nutritional decisions.
