If you’re feeling exhausted, not able to sleep, and mood is all over the place and your doctor says: your labs look normal, here’s what I want you to know!

Standard lab panels almost never test for micronutrient deficiencies like magnesium, omega 3 fats and more. And nutrient deficiencies are so common! 

In 2005 I had my first nutrient deficiency test done and learning this information about my body was so eye opening. 

In 2014, I started running nutrient deficiency testing on thousands of women, alongside the brilliant doctors I worked with at the Cleveland Clinic Center for Functional Medicine. 

And I continued doing so with my team of Dietitians in our virtual nutrition business. 12 years later, I can tell you that we see nutrient deficiencies flagged every single day, even in women who eat very healthy diets.

In today’s article, I’m sharing the five most common nutrient deficiencies I see in women, the symptoms they cause, how to get the right tests, and exactly what you can do about it.

Why Nutrient Deficiencies Go Undetected

Micronutrients are the building blocks for every cellular process in your body. 

Each of your cells contains more than 1,000 mitochondria responsible for producing energy and those mitochondria are completely dependent on vitamins and minerals. 

Yet most conventional doctors aren’t testing for them, and when they do, they’re using reference ranges that identify only severe deficiency, not the optimal levels your body needs to truly thrive.

The result? Women being told their labs are “normal” while experiencing a long list of symptoms. 

Common symptoms linked to nutrient deficiencies:

• Extreme fatigue and low energy
• Insomnia and disrupted sleep
• Anxiety, depression, and mood swings
• Brain fog, difficulty focusing, and memory issues
• Blood sugar imbalances and poor metabolic health
• Hormonal disruptions and PMS
• Chronic inflammation
• Cognitive decline

Nutrient #1: Magnesium

Magnesium is one of the most important minerals in the human body and one of the most chronically depleted. It’s involved in over 300 enzymatic reactions, meaning even a modest deficiency can trigger a cascade of problems throughout your entire system.

What Magnesium Does

• Regulates muscle and nerve function
• Supports energy production and reduces fatigue
• Improves sleep quality
• Controls blood sugar and insulin sensitivity
• Reduces blood pressure through vasodilation
• Lowers inflammatory markers (interleukin-6 and TNF-alpha)
• Calms the central nervous system and reduces stress sensitivity
• Supports HPA axis regulation (your stress-response system)

The Magnesium-Stress Cycle You Need to Know

When magnesium levels are low, your adrenal glands become much more reactive to small stressors, releasing adrenaline and cortisol at a lower threshold. Stress itself then causes you to excrete more magnesium through urine. This can create a vicious cycle: low magnesium increases stress reactivity, which depletes magnesium further.

A 2016 study on rugby players found that magnesium supplementation significantly reduced interleukin-6 (an inflammatory marker released during physical stress) and improved HPA axis activity compared to the control group.

Signs You May Be Deficient

• Muscle cramps or twitching
• Numbness or tingling
• Fatigue and weakness
• Irregular heartbeats
• Elevated blood pressure
• Nausea or decreased appetite
• Difficulty staying asleep

How to Get More Magnesium

Top food sources:

• Pumpkin seeds
• Almonds
• Spinach and kale
• Beans and legumes
• Dark chocolate
• Epsom salt baths (magnesium absorbs through skin!)

Supplementation form matters: magnesium bisglycinate and magnesium citrate are most commonly recommended depending on your symptoms.

Nutrient #2: Omega-3 Fatty Acids

Every woman should know her omega-3 index. This is one of the most powerful, measurable markers of inflammation in your body. And omega 3s are severely lacking in the American diet.

Omega-3 polyunsaturated fats (EPA and DHA) increase production of anti-inflammatory compounds and reduce pro-inflammatory cytokines like TNF-alpha and reactive oxygen species. Because omega-3s are essential fatty acids, your body cannot produce them. That means you need to get enough from food and supplementation.

Target Range to Aim For

Optimal Omega Index: 8-12%

This therapeutic range supports cognitive health, cardiovascular health, hormonal balance, lower rates of depression and a healthy inflammatory response. 

Conditions Improved by Optimal Omega-3 Levels

• Chronic inflammation
• Inflammatory bowel disease
• Cognitive decline and memory issues
• Cardiovascular issues (high cholesterol, hypertension)
• Osteoarthritis
• Depression
• Hormonal imbalances
• Fatigue

How to Get More Omega-3s

Aim for 2–3 servings per week of omega-3-rich fish: salmon, mackerel, sardines, anchovies. Plant-based sources like chia and flaxseeds provide ALA, but most women only convert about 8–10% into usable EPA and DHA — and this conversion becomes even less efficient through menopause. Even eating fish 2–3x per week, many women still test deficient. Targeted supplementation with the right dose is often essential.

Nutrient #3: Vitamin D

Vitamin D is the one nutrient most doctors do test. But they’re often interpreting the results incorrectly. Conventional labs flag anything above 30 ng/mL as “normal.” From a health-optimization standpoint, that bar is far too low.

Vitamin D functions as both a vitamin and a pro-hormone, meaning it plays a direct role in hormone production, immune regulation, nervous system function, mood, and metabolic health.

Know Your Numbers

Conventional ‘Normal’: Above 30 ng/mL

Optimal Therapeutic Range: 60-80ng/mL 

Vitamin D is a fat soluble nutrient, meaning excessive levels can be toxic. Always test before supplementing at higher doses. 

What Vitamin D Supports

• Bone density and musculoskeletal health
• Immune strength (antiviral and antimicrobial properties)
• Mood stability and mental health
• Central nervous system and stress resilience
• Insulin sensitivity and blood sugar regulation
• Hormone production

Factors That Reduce Absorption

• Darker skin pigmentation
• Higher body fat percentage
• Older age
• Living in northern climates or areas with limited sunlight
• Consistent sunscreen use

How to Optimize Vitamin D

Food sources: fatty fish, pasture-raised eggs, mushrooms grown in sunlight. 15 minutes of direct sun exposure without sunscreen can meaningfully support synthesis. Adults without regular sun exposure during winter may need 5,000+ IU daily — but testing 1–2x per year is essential to dial in the right dose.

Nutrient #4: B Vitamins (Especially B12 and B6)

B vitamins — B1, B2, B3, B6, B9 (folate), B12, and biotin — are essential for energy production, neurological function, hormonal balance, and mood. B12 and B6 are the deficiencies we see most frequently in women.

Vitamin B12: The Energy and Brain Vitamin

Vitamin B12 absorption naturally declines with age as stomach acid decreases. Your body needs intrinsic factor to absorb B12, and production of this drops over time. This makes B12 deficiency increasingly common.

Common symptoms:

• Extreme fatigue
• Anxiety and depressive symptoms
• Hormonal imbalances
• Cognitive decline
• Difficulty finding words (tip-of-the-tongue recall)

A B12 level of 200 pg/mL may not be flagged as deficient by your doctor but it’s far from optimal. Women who double or triple their B12 levels through targeted supplementation often see dramatic improvements in energy, clarity, and mood. 

If absorption is poor, sublingual (under-the-tongue) B12 or injections may be more effective than oral supplements.

Best food sources: liver and organ meats (highest), grass-fed beef, chicken, salmon. 

Vitamin B6: The Mood and Hormone Regulator

Vitamin B6 is central to neurotransmitter synthesis. It directly impacts serotonin, dopamine, and GABA, making it foundational for mood stability. It’s also involved in progesterone receptor sensitivity and estrogen metabolism, making it critical for hormonal balance, PMS symptoms, and blood sugar regulation.

Best food sources: salmon, chicken, grass-fed beef, beef liver, eggs, chickpeas (highest plant-based source), sweet potatoes, avocado, sunflower seeds.

Nutrient #5: Zinc

Most people associate zinc with immune support. And yes–the research does show an association. But zinc does far more: it’s critical for hormone production, fertility, nervous system health, and even muscle development.

Zinc’s Role in Women’s Hormonal Health

• Co-factor for enzymes involved in testosterone synthesis. And we know low testosterone causes fatigue, low libido, and poor muscle gains even with strength training
• Supports healthy follicular development and egg quality
• The corpus luteum requires zinc to produce progesterone, supporting the luteal phase and early pregnancy
• Deficiency is linked to irregular cycles, lack of ovulation, and difficulty conceiving

The Zinc-Copper Connection

Zinc and copper levels are directly connected and influence each other. Over-supplementing with zinc (this was common during COVID) can deplete copper levels. 

If you supplement with zinc, it must be in a form and dose that doesn’t disrupt your zinc-to-copper ratio — another reason why testing before supplementing matters.

Best Food Sources of Zinc

• Oysters — the single highest food source (canned smoked oysters from Trader Joe’s or Thrive Market are a great option)
• Grass-fed beef
• Pumpkin seeds
• Lentils and chickpeas
• Hemp seeds
• Cashews

The Bigger Picture: It’s Not Just What You Eat — It’s What You Absorb

Nutrient deficiencies in women are not always a consumption problem. They can also be an absorption problem.

We regularly see deficiencies in women eating beautiful organic vegetables, quality proteins, and mostly whole foods. The issue is poor digestion, leaky gut, bacterial overgrowth, or chronic stress directly impairing the body’s ability to absorb what it’s consuming.

The approach that I take isn’t simply to take a supplement for every flagged deficiency. It’s to ask: why is your body not absorbing what it’s being given?

Here’s what it can look like: 

+Step 1: Test, don’t guess. Run an organic acid test to help you better understand underlying deficiencies, neurotransmitter production, mitochondrial health and more. 

+Step 2: Understand your optimal therapeutic ranges, not just what’s “normal” 

+Step 3: Work to address the root cause. Why aren’t you absorbing these nutrients? 

+Step 4: Implement a personalized plan for specific nutrition and supplement recommendations tailored to your labs. 

Stop Guessing and Start Testing

If you’re tired of piecing these puzzle pieces together on your own, My Food is Health is my 12-week virtual program where we run an organic acid test on every participant to assess nutrient deficiencies and then provide a personalized nutrition and supplement plan supported by a team of Registered Dietitians.

Visit My Food is Health to learn more, or schedule a discovery call with lead dietitian Michelle to see if the program is right for you https://l.bttr.to/BLkbg.