How to Spot Nutrient Deficiencies from Common Symptoms

Introduction

Not every symptom is a diagnosis. In fact, some of the most common complaints I hear — fatigue, irritability, dry skin, poor sleep — often stem from suboptimal nutrition, not disease. Our bodies rely on a constant supply of micronutrients to function. When we fall short, even slightly, symptoms begin to appear. The good news? Once identified, most deficiencies are correctable. Here’s how I connect the dots in patients with vague but persistent symptoms.

Why Are Nutrient Deficiencies So Common?

Today’s food system often prioritizes convenience over quality. Even people eating “healthy” diets can miss key nutrients due to:

• Soil depletion (lower mineral content in crops)
• Highly processed foods
• Restricted eating patterns
• Digestive issues or malabsorption
• Medication use (e.g., PPIs, metformin, birth control)
• Stress, which increases nutrient needs

Many deficiencies don’t cause disease — but they do create low-grade symptoms that affect daily life.

What Are the Most Common Deficiencies I See?

• Iron
• Vitamin D
• Magnesium
• Vitamin B12
• Omega-3 fatty acids
• Folate
• Zinc

Each of these has distinct symptoms — and blood tests to confirm.

What Symptoms Might Point to a Deficiency?

1. Fatigue or Brain Fog

• B12: Often low in vegetarians/vegans
• Iron: Especially in menstruating women
• Vitamin D or folate: Low levels impact energy and cognition

2. Muscle Cramps or Twitches

• Magnesium: Commonly depleted with stress or poor sleep
• Calcium: Often low in those with dairy-free diets

3. Hair Loss or Brittle Nails

• Iron, zinc, and biotin: All support hair and nail growth
• Protein deficiency: Can weaken structural tissues

4. Mood Swings or Anxiety

• Magnesium and B6: Both support neurotransmitter balance
• Omega-3s: Anti-inflammatory fats for brain health

5. Pale Skin or Dark Circles

• Iron: Essential for oxygen delivery
• B12: Deficiency can cause pallor and fatigue

What Blood Tests Can Help?

Ask your provider about:

• Ferritin (iron stores)
• Vitamin D (25-hydroxy)
• B12 and folate
• Magnesium (ideally RBC magnesium)
• Omega-3 index (via blood spot testing)
• Homocysteine (sensitive to B12, folate, B6)

Functional testing like micronutrient panels can also identify borderline deficiencies before they become symptomatic.

How Should You Replenish?

Start with food, then supplement if needed.

Top Food Sources by Nutrient

• Iron: Red meat, lentils, spinach (pair with vitamin C)
• Magnesium: Pumpkin seeds, leafy greens, dark chocolate
• B12: Meat, fish, eggs, fortified plant milks
• Omega-3s: Fatty fish, flaxseeds, walnuts
• Zinc: Oysters, beef, pumpkin seeds

If supplementing, aim for high-quality brands, ideally third-party tested for purity and absorption.

Should You Supplement Just In Case?

Not necessarily. While a basic multivitamin can help cover gaps, targeted supplementation based on testing is more effective and safer.

That said, I often recommend magnesium and D3/K2 as baseline support in most adults, especially during winter or periods of high stress.

Final Thoughts

Your body gives clues when something is missing — you just have to know how to listen. Instead of dismissing low energy, poor sleep, or brittle nails as “just stress,” ask what your body might be lacking.

Start with diet, ask for key lab tests, and use supplements strategically. With the right inputs, your body can rebuild and thrive — no mystery illness required.