Nutrient Status Evidence

Micronutrient Deficiency Prevalence

The World Health Organization (WHO) states that micronutrients are vital to healthy development, growth, disease prevention, and overall well-being.R65 The Centers for Disease Control and Prevention (CDC) reports that, in the general U.S. population, deficiency rates are about 10% for vitamin B6, vitamin D, and iron, with meaningful subgroup variation.R9 A nationally representative National Health and Nutrition Examination Survey (NHANES)-based review found substantial inadequacy in several immune-related nutrients, including vitamins A, C, D, E, and zinc.R49 The National Institutes of Health (NIH) Dietary Reference Intakes (DRI) establish the recommended intake levels for vitamins and minerals that define adequacy and deficiency thresholds used in clinical evaluation.R39 The U.S. Department of Agriculture (USDA) Dietary Guidelines for Americans identify key nutrients of public health concern — including calcium, vitamin D, potassium, and iron — where intake gaps are most clinically significant.R60

Absorption, Gut Integrity, and Clinical Impact

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) states that celiac disease damages the small intestine and can keep the body from getting the nutrients it needs.R37 Beyond diagnosed conditions, compromised gut integrity — sometimes referred to as increased intestinal permeability or "leaky gut" — can impair the absorption of nutrients even when dietary intake appears adequate. When the intestinal lining is not functioning optimally, nutrients may pass through the gut without being properly absorbed, contributing to functional deficiencies that are not explained by diet alone.R58 This is a clinically important distinction: a patient may be consuming sufficient nutrients yet still present with deficiency patterns if absorption is impaired.

Lactose Intolerance and Nutrient Utilization

NIDDK explains that lactose intolerance reflects a specific form of absorption dysfunction in which the small intestine cannot fully digest lactose, illustrating how targeted intolerance patterns can directly affect nutrient utilization and overall digestive comfort.R38 Identifying these patterns through structured testing supports more precise dietary guidance.

Clinical Implication for Providers

The distinction between intake and absorption is clinically meaningful. A patient who is eating well or supplementing appropriately but not progressing may warrant investigation into whether nutrients are being absorbed and utilized effectively. Nutrient status testing can reveal these gaps, giving providers a more complete picture of what is driving persistent symptoms or limited clinical progress.