Micronutrient inadequacy vs. deficiency, why they are not the same?

Key Take Outs

Establishing adequate intake
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Adequate Intake values
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Establishing deficiency
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Clinical implications
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01Establishing adequate intake
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02Adequate Intake values
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03Establishing deficiency
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04Clinical implications
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Ariana D. Bailey, PhD & Ashley C. Patterson, PhD

Does inadequate micronutrient intake mean a person is micronutrient deficient? Not necessarily.

In the article "Micronutrient Inadequacy vs. Deficiency: An Overview of Concepts, Measurement, and Implications," published in Nutrients by Mary R. L'Abbé and Heather H. Keller, the authors delve into the distinctions between these two terms, shedding light on their significance in the context of public health and clinical practice.

Inadequate micronutrient intake

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Micronutrient deficient

In a 2021 publication on nutrient intake for children 1-6 years of age based on analysis of National Health and Nutrition Examination Survey (NHANES) 2001-2016 data, iron and vitamin B6 deficiencies were found, despite adequate intake of both micronutrients among the majority of the study population. The reason for this is unknown but may be due to differing bioavailability of these micronutrients in different food sources, or the estimated average requirements (EAR) for intake of these nutrients are too low for children aged 1-6 years, or overreported intake.¹

Micronutrient inadequacy vs. deficiency, why they are not the same? - Table 1

Serum biomarker	% Population below cut-off for deficiency¹
	1-2 y	2-3 y	4-6 y	1-6 y
Ferritin	13	9	3.7	7.4
Hemoglobin	4.3	2.8	1.6	2.5
Vitamin B6	7.9	6.4	5.8	6.4

Cut-off values for deficiencies: ferritin, 12ng/mL (applied as cut-off for iron deficiency); hemoglobin, 11g/dL (applied as cut-off for anemia); vitamin B6, 20nmol/L.

Take iron as an example – spinach is often cited as a good source of iron, particularly for people who don’t eat meat, seafood or poultry. But the iron in spinach is a ‘non-heme iron’ (mainly found in plant sources and in fortified foods) which has lower bioavailability than ‘heme iron’ available only in animal products. Therefore, vegetarians need to consume almost twice as much iron as recommended for people who eat meat.^2,3

Establishing adequate intake

Estimated Average Requirements or EAR is the nutrient intake value that is estimated to meet the requirement of half the healthy individuals of a group. Not meeting EAR values establishes inadequacy of intake for a group:

For example, we can say: “~87% of US children 1-6 years of age have inadequate intakes of vitamin D.”

However, not meeting EAR values does not demonstrate deficiency:

We cannot say: “~87% of US children 1-6 years of age have vitamin D deficiency.”

What about Adequate Intake values?

An Adequate Intake or AI reference value is given to a nutrient when there isn’t enough evidence to calculate an EAR. The AI considers estimates of observed median nutrient intake by a group and is expected to meet or exceed group needs. AI values are established differently for each micronutrient and the relationship to the true requirement for the micronutrient is unknown. This means that it cannot be used to estimate if a proportion of the population has inadequate intake:

For example, we can say: “40% of children 1-6 years of age had adequate intakes of choline.”

We cannot subtract the 40% from 100 to get the inverse:

So, we cannot say: “60% of children 1-6 years of age had inadequate intakes of choline.”

With this in mind, let’s have a quick look at how to determine micronutrient deficiency.

How do we establish deficiency?

Ideally, micronutrient deficiency should be determined by a valid and reliable biomarker relative to reference values. Biomarkers are typically defined as biological measurements (i.e., blood, urine, etc.) that are used to indicate ‘normal biological processes, pathogenic processes, or pharmacologic responses to therapeutic intervention’.^4,5

Clinical implications

Now you understand that inadequate intakes and micronutrient deficiencies are defined differently. What do they mean to clinicians and dietitians?

The results from this study on nutrient intake for children 1-6 years of age¹ highlight the importance of dietary counseling and personalized nutrition. For example, understanding your patients’ dietary preferences and restrictions may help you to decide whether it would be necessary to test certain nutrient biomarkers. Other factors to consider include your patients’ age, medical history, poverty level, and ethnicity.

The full study and results can be accessed at: https://doi.org/10.3390/nu13030827.

Bailey A, Fulgoni III V, Shah N, Patterson A, Gutierrez-Orozco F, Mathews R, Walsh K. Nutrient intake adequacy from food and beverage intake of US children aged 1–6 years from NHANES 2001–2016. Nutrients 2021, 13(3):827. https://doi.org/10.3390/nu13030827
Hurrell R, Egli I: Iron bioavailability and dietary reference values. Am J Clin Nutr 2010, 91(5):1461S-1467S. https://doi.org/10.3945/ajcn.2010.28674f
National Institute of Health. Iron fact sheet – health professionals [Internet; cited 2024 Aug 29]. Available from: https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/
Strimbu K, Tavel JA: What are biomarkers? Curr Opin HIV AIDS 2010; 5: 463–466. https://doi.org/10.1097/coh.0b013e32833ed177
Bailey RL., West Jr KP, Black RE: The epidemiology of global micronutrient deficiencies. Ann Nutr Metab 2015, 66:22-33. https://doi.org/10.1159/000371618