The Four Most Overlooked Vitamin Deficiencies That Affect Energy, Mood, and Focus

By Nervana Medical – Integrative Health & Wellness, Sandy, Utah

Even in higher-income countries like the United States, vitamin and nutrient deficiencies remain surprisingly common. At Nervana Medical, we routinely see patients with low levels of key nutrients such as vitamin D, vitamin B6, vitamin B12, and iron; often without obvious symptoms at first. These deficiencies can affect energy, mood, hormones, immune function, and long-term health.

Let’s look at what the latest research shows, who is most at risk, and how testing and targeted replacement can help restore balance and wellbeing.

The Most Common Deficiencies Found in Lab Testing

1. Vitamin D

• Prevalence: Around 26 % of adults have vitamin D insufficiency, and 5–7 % have outright deficiency.
• Why it matters: Vitamin D supports bone strength, immunity, mood regulation, and inflammation balance.
• Why it’s common: Limited sun exposure, sunscreen use, darker skin tones, and indoor lifestyles all reduce natural vitamin D production.
• Optimization goal: We typically aim for 50–80 ng/mL of 25-OH vitamin D for optimal function, though this depends on each patient individually
  

2. Vitamin B6

• Prevalence: Roughly 16–23 % of adults show low levels of vitamin B6.
• Why it matters: B6 is essential for neurotransmitter production (serotonin, dopamine, GABA), red-blood-cell health, and nervous-system function.
• Common causes: Poor diet, certain medications (like oral contraceptives or some blood-pressure meds), and stress can all lower B6.
• Optimization goal: Maintain plasma PLP (the active form) around 30–60 nmol/L.
  

3. Vitamin B12

• Prevalence: Found in 2–4 % of adults, but deficiency rates rise with age.
  Why it matters: Low B12 can cause fatigue, depression, brain fog, numbness, balance problems, and long-term nerve damage if untreated.
  At-risk groups: Older adults, vegans/vegetarians, and anyone taking metformin or acid-blocking medications.
• Optimization goal: Keep serum B12 above 400 pg/mL; higher for patients with neurologic or mood symptoms.
  

4. Iron

• Prevalence: About 20 % of women in the U.S. and U.K. have low ferritin (iron storage).
• Why it matters: Even mild iron deficiency—before anemia develops—can cause fatigue, headaches, poor concentration, low mood, or hair thinning.
• At-risk groups: Women of reproductive age, frequent blood donors, those with heavy menstrual bleeding or plant-based diets.
  

How These Deficiencies Affect Mental and Physical Health

Each of these nutrients plays a key role in energy metabolism, neurotransmitter production, and hormonal balance. When levels are suboptimal, symptoms may overlap with common mental-health complaints such as low mood, anxiety, brain fog, or fatigue.
At Nervana Medical, we often identify subtle deficiencies in patients being treated for mood disorders, chronic fatigue, or hormone imbalance. Correcting these can dramatically improve treatment response and overall quality of life.

---

Who Should Consider Testing

Targeted serum testing is especially helpful for:

• Women of reproductive age or during perimenopause
• Older adults
• Those with limited sun exposure or restrictive diets
• Patients with chronic illnesses (thyroid disease, IBD, DM,CKD, autoimmune disorders)
• Anyone experiencing fatigue, low mood, or cognitive changes despite normal labs elsewhere
  

Our functional approach includes comprehensive panels for vitamins D, B6, B12, and ferritin, plus optional hormone and nutrient testing (magnesium, folate, thyroid, testosterone, estrogen, and cortisol).

How We Treat and Prevent Deficiencies

Nutrient	Typical Approach	Common Target
Vitamin D	Oral or sublingual D3, 2000–4000 IU/day, plus safe sun exposure *Consider with K2 if felt to have K2 deficiency	30–50 ng/mL
Vitamin B6	Oral PLP or IM/IV repletion if needed; 50–100 mg weekly	50–80 nmol/L PLP
Vitamin B12	Oral or injectable methylcobalamin (1000–2000 mcg)	>400 pg/mL
Iron	Dietary increase, oral iron (18–45 mg/day), or IV iron if needed	Ferritin >50 ng/mL

We always personalize dosing and frequency based on your lab results, diet, and symptoms. Our team also ensures levels stay in the optimal; not excessive range, as very high doses can cause side effects just as low doses can also. We typically recommend rotating supplementation of these vitamins/nutrients when replacing paternally for those who prefer paternal replacement.

Functional Medicine Perspective

Functional medicine focuses on identifying the root cause of deficiencies; whether it’s poor absorption, low intake, inflammation, or medication effects and restoring balance through diet, lifestyle, and individualized supplementation.
This proactive approach not only corrects lab abnormalities but also helps patients feel better, recover faster, and prevent long-term complications.

---

Takeaway

Even in well-nourished populations, deficiencies in vitamin D, B6, B12, and iron are common and can silently affect energy, mood, and overall vitality.
Routine testing, guided by your provider, helps ensure you’re not running on empty.

At Nervana Medical, we offer comprehensive micronutrient panels and personalized repletion plans; through oral, IV, or IM therapy to help you feel and function your best.

---

References 

1. Allen LH. Micronutrients — Assessment, Requirements, Deficiencies, and Interventions. The New England Journal of Medicine. 2025;392(10):1006–1016. doi:10.1056/NEJMra2314150.
   
2. Patel H, McGuirk R. Vitamin B12 Deficiency: Common Questions and Answers. American Family Physician. 2025;112(3):294–300.
   
3. Han X, Ding S, Lu J, Li Y. Global, Regional, and National Burdens of Common Micronutrient Deficiencies From 1990 to 2019: A Secondary Trend Analysis Based on the Global Burden of Disease 2019 Study. EClinicalMedicine. 2022;44:101299. doi:10.1016/j.eclinm.2022.101299.
   
4. Bird JK, Murphy RA, Ciappio ED, McBurney MI. Risk of Deficiency in Multiple Concurrent Micronutrients in Children and Adults in the United States. Nutrients. 2017;9(7):E655. doi:10.3390/nu9070655.
   
5. Grant WB, Wimalawansa SJ, Pludowski P, Cheng RZ. Vitamin D: Evidence-Based Health Benefits and Recommendations for Population Guidelines. Nutrients. 2025;17(2):277. doi:10.3390/nu17020277.
   
6. Vanek VW, Borum P, Buchman A, et al. A.S.P.E.N. Position Paper: Recommendations for Changes in Commercially Available Parenteral Multivitamin and Multi-Trace Element Products. Nutrition in Clinical Practice. 2012;27(4):440–491. doi:10.1177/0884533612446706.
   
7. Auerbach M, DeLoughery TG, Tirnauer JS. Iron Deficiency in Adults: A Review. JAMA. 2025;333(20):1813–1823. doi:10.1001/jama.2025.0452.
   
8. Benson AE, Lo JO, Achebe MO, et al. Management of Iron Deficiency in Children, Adults, and Pregnant Individuals: Evidence-Based and Expert Consensus Recommendations. The Lancet Haematology. 2025;12(5):e376–e388. doi:10.1016/S2352-3026(25)00038-9.
   
9. Krist AH, Davidson KW, Mangione CM, et al. Screening for Vitamin D Deficiency in Adults: US Preventive Services Task Force Recommendation Statement. JAMA. 2021;325(14):1436–1442. doi:10.1001/jama.2021.3069.
   
10. Gana W, De Luca A, Debacq C, et al. Analysis of the Impact of Selected Vitamins Deficiencies on the Risk of Disability in Older People. Nutrients. 2021;13(9):3163. doi:10.3390/nu13093163.
    
11. Kato N, Kimoto A, Zhang P, et al. Relationship of Low Vitamin B6 Status With Sarcopenia, Frailty, and Mortality: A Narrative Review. Nutrients. 2024;16(1):177. doi:10.3390/nu16010177.
    
12. Obeid R, Andrès E, Češka R, et al. Diagnosis, Treatment and Long-Term Management of Vitamin B12 Deficiency in Adults: A Delphi Expert Consensus. Journal of Clinical Medicine. 2024;13(8):2176. doi:10.3390/jcm13082176.
    
13. Papazachariou A, Papakitsou I, Malikides V, Filippatos TD. Vitamin B12 Deficiency Among Older Adults and Its Associations With Geriatric Syndromes. Current Opinion in Clinical Nutrition and Metabolic Care. 2025;:00075197–990000000–00252. doi:10.1097/MCO.0000000000001171.
    
14. Santos HO, Martins CEC, Forbes SC, Delpino FM. A Scoping Review of Vitamin D for Nonskeletal Health: A Framework for Evidence-Based Clinical Practice. Clinical Therapeutics. 2023;45(5):e127–e150. doi:10.1016/j.clinthera.2023.03.016.
    
15. Demay MB, Pittas AG, Bikle DD, et al. Vitamin D for the Prevention of Disease: An Endocrine Society Clinical Practice Guideline. The Journal of Clinical Endocrinology & Metabolism. 2024;109(8):1907–1947. doi:10.1210/clinem/dgae290.
    
16. Fiani D, Chahine S, Zaboube M, et al. Psychiatric and Cognitive Outcomes of Iron Supplementation in Non-Anemic Children, Adolescents, and Menstruating Adults: A Meta-Analysis and Systematic Review. Neuroscience and Biobehavioral Reviews. 2025. doi:10.1016/j.neubiorev.2025.106372.
    
17. Hashash JG, Elkins J, Lewis JD, Binion DG. AGA Clinical Practice Update on Diet and Nutritional Therapies in Patients With Inflammatory Bowel Disease: Expert Review. Gastroenterology. 2024;166(3):521–532. doi:10.1053/j.gastro.2023.11.303.
    
18. Reddy P. Preventing Vitamin B6-Related Neurotoxicity. American Journal of Therapeutics. 2022 Nov–Dec;29(6):e637–e643. doi:10.1097/MJT.0000000000001460.
    
19. Mahadzir MDA, Tan S, Elena S, et al. Towards Defining Optimal Concentrations of Micronutrients in Adults to Optimize Health. Mechanisms of Ageing and Development. 2025;225:112062. doi:10.1016/j.mad.2025.112062.
    
20. Brown KH, Hess SY, Moore SE, et al. Neglected Micronutrients – Considering a Broader Set of Vitamins and Minerals in Public Health Nutrition Programs Worldwide: A Narrative Review. The American Journal of Clinical Nutrition. 2025. doi:10.1016/j.ajcnut.2025.06.030.
    
21. Cashman KD. Vitamin D Deficiency: Defining, Prevalence, Causes, and Strategies of Addressing. Calcified Tissue International. 2020;106(1):14–29. doi:10.1007/s00223-019-00559-4.
    
22. Wimalawansa SJ. Physiology of Vitamin D – Focusing on Disease Prevention. Nutrients. 2024;16(11):1666. doi:10.3390/nu16111666.
    
23. Langan RC, Goodbred AJ. Vitamin B12 Deficiency: Recognition and Management. American Family Physician. 2017;96(6):384–389.
    
24. Wolffenbuttel BHR, McCaddon A, Ahmadi KR, Green R. A Brief Overview of the Diagnosis and Treatment of Cobalamin (B12) Deficiency. Food and Nutrition Bulletin. 2024;45(1 Suppl):S40–S49. doi:10.1177/03795721241229500.
    
25. Iriarte-Gahete M, Tarancon-Diez L, Garrido-Rodríguez V, Leal M, Pacheco YM. Absolute and Functional Iron Deficiency: Biomarkers, Impact on Immune System, and Therapy. Blood Reviews. 2024;68:101227. doi:10.1016/j.blre.2024.101227.
    
26. Mahadzir MDA, Tan S, Elena S, et al. Towards Defining Optimal Concentrations of Micronutrients in Adults to Optimize Health. Mechanisms of Ageing and Development. 2025;225:112062. doi:10.1016/j.mad.2025.112062.