2.1: Nutritional Status

Nutritional adequacy implies daily optimal nutrient intake for optimal physiological function. This may vary from person to person, as everyone has their own slightly different nutritional needs. Though in any individual, optimal nutrient intake (nutritional adequacy) correlates with optimal health impacts (Figure 2.1).

Figure 2.1 Optimal nutrient intake correlates with optimal health effects. “Bell curve of intake vs health effect” is from the Medical gallery of Mikael Häggström 2014, WikiJournal of Medicine. Licensed by Creative Commons CC0 1.0.

With too little intake of a nutrient, we can end up in a deficiency, or undernutrition, status. On the other end of the bell curve is nutritional toxicity, resulting from overconsumption of a nutrient. Either of these situations would be considered malnutrition — a state of poor nutrition with an imbalance between the nutrients required and nutrients consumed. A primary malnutrition is typically due to inadequate or excess food intake, whereby the malnutrition can be addressed by a change in diet. A secondary malnutrition is typically due to other factors such as an underlying condition. For example, a person may be deficient in vitamin B1 because their diet is lacking vitamin-rich fruits and vegetables, or because an illness interferes with the absorption of vitamin B1. Someone with celiac disease, a digestive disorder triggered by an immune reaction to gluten (protein in wheat, barley, and rye) that damages the intestinal lining, may have multiple nutritional deficiencies, not because they aren’t eating well (this would be a primary malnutrition) but because their damaged intestines can’t absorb and use the nutrients they’re consuming (hence, a secondary malnutrition).

Diet Assessment for Nutritional Adequacy

Clinical methodology can be used to assess nutritional status. A clinical exam can assess a patient’s medical history and appearance of skin, hair, eyes, and so forth. Anthropometric measurements can be taken to establish height, weight, and body circumference. Blood and/or urine tests can be obtained to look at things such as protein status or vitamin and mineral status. Biomarkers, or indicators that reflect a nutrient’s function, can be evaluated. For example, hemoglobin content of the blood is often measured as a biomarker for iron status. This is because hemoglobin levels decrease during iron deficiency; so, biomarkers can help diagnose a specific nutrient issue. Even further, clinicians can assess body composition, distribution of fat, water, muscle, and mineral mass in tissues, or perform functional neurological or developmental tests that imply nutrient status.

Whether seeking the help of a clinician for assessment of nutritional status and adequate intake or using one’s own resources, retrospective and/or prospective dietary assessments are tools used to aid in the understanding of an individual’s intake.

Retrospective Dietary Assessments

Retrospective dietary assessments are methods used to evaluate an individual’s past food and nutrient intake, typically relying on memory and self-reporting. Common tools include food frequency questionnaires (FFQs) (Table 2.1), 24- hour dietary recalls, and diet histories. These assessments are valuable in epidemiological research and clinical settings to identify dietary patterns, estimate nutrient intake, and explore associations between diet and health outcomes. However, their accuracy can be limited by recall bias, misreporting, and the difficulty individuals may have in estimating portion sizes or remembering food consumed over extended periods. Additionally, humans tend to lack honesty with these tools, often overestimating the amount and frequency at which they’re consuming “healthy” items and underestimating “unhealthy” items. Despite these limitations, retrospective assessments remain widely used due to their practicality and cost-effectiveness compared to prospective methods.

Table 2.1 Food frequency questionnaire example

Food Item	Never	1–3x/ month	1x/ week	2–4x/ week	5–6x/ week	1x/day	2–3x/day	4–5x/day	6+x/day
Fruits (apples, bananas, etc.)	☐	☐	☐	☐	☐	☐	☐	☐	☐
Vegetables (carrots, potatoes, etc.)	☐	☐	☐	☐	☐	☐	☐	☐	☐
Dairy (cheese, milk, yogurt, etc.)	☐	☐	☐	☐	☐	☐	☐	☐	☐
Red meat (beef, pork, lamb)	☐	☐	☐	☐	☐	☐	☐	☐	☐
Sweetened beverages	☐	☐	☐	☐	☐	☐	☐	☐	☐
Leafy greens (spinach, kale, etc.)	☐	☐	☐	☐	☐	☐	☐	☐	☐
Grains (breads, pasta, rice, etc.)	☐	☐	☐	☐	☐	☐	☐	☐	☐
Sweets (candy, cookies, pie, etc.)	☐	☐	☐	☐	☐	☐	☐	☐	☐
Nuts (almonds, cashews, etc.)	☐	☐	☐	☐	☐	☐	☐	☐	☐

Prospective Dietary Assessments

Prospective dietary assessments involve the real-time or forward-looking collection of dietary intake data, typically recorded by individuals as they consume foods and beverages. Common methods include food diaries or food records, where individuals document everything they eat and drink over a specified period, often ranging from three to seven days (Table 2.2). The ideal prospective assessment is kept for at least three days, including part of a weekend to account for potential variations in diet from weekdays to weekends. These are typically considered to be one of the most accurate dietary assessment methods. This approach reduces reliance on memory and can provide more accurate and detailed information about portion sizes, meal timing, and preparation methods. Many computerized nutrient databases now exist to allow ease of recording intake as well as caloric and nutrient consumption. And while prospective methods can yield high-quality data, they may still be burdensome for people and prone to underreporting or changes in eating behavior due to increased self-awareness. Despite these challenges, prospective assessments are valuable tools in both research and clinical practice for closely monitoring dietary intake and identifying relationships between diet and health outcomes.

Table 2.2 Example day of dietary journal

Time	Food & Beverage	Amount	Notes (Hunger, Mood, etc.)
7:30 AM	Oatmeal with banana and almonds	1 cup oatmeal, 1/2 banana, 1 tbsp almonds	Slightly hungry, feeling good
10:00 AM	Greek yogurt with honey	1 small container, 1 tsp honey	Light snack, felt energized
12:45 PM	Grilled chicken sandwich, side salad	1 sandwich, 1 cup salad	Moderately hungry, satisfied after
3:30 PM	Apple and peanut butter	1 medium apple, 1 tbsp PB	Craving something sweet
6:30 PM	Spaghetti with marinara sauce, steamed broccoli	1.5 cups pasta, 1 cup broccoli	Very hungry, comfort meal
8:00 PM	Herbal tea and chocolate chip cookies	1 cup tea, 4 cookies	Relaxed, nice treat