Folic Acid in Winter: Why Deficiency Is Not Just a Pregnancy Issue

Folic acid (Vitamin B9) and its role in mood, hematopoiesis, and body detoxification.

Introduction

Folic acid is often mentioned in the context of pregnancy — supposedly a “women’s vitamin”.
In reality, vitamin B9 is needed by everyone, especially in autumn and winter, when the body switches to energy-saving mode and the diet becomes poorer in green vegetables.

Folic acid is involved in the synthesis of DNA, cell division, the production of red blood cells, and the regulation of homocysteine — an amino acid whose excess increases the risk of heart attacks and depression.
Therefore, B9 deficiency is not only about fertility, but also about energy, mood, and longevity.

How folic acid works

After absorption in the intestines, B9 is converted into 5-MTHF (methyl-tetrahydrofolate) — the active form that:

• transfers one-carbon groups during DNA synthesis;

• participates in the production of serotonin, dopamine, and norepinephrine;

• together with vitamins B12 and B6 lowers homocysteine levels — a toxic metabolite.

This process explains why folic acid affects the brain, mood, and heart.

Table 1. Main functions of folic acid

Why B9 deficiency is more common in winter

• Fewer fresh vegetables and greens.

• More frequent consumption of coffee, alcohol, and sugar, which reduce absorption.

• Use of antibiotics, contraceptives, or metformin — reduces bioavailability.

• Genetic MTHFR variants (in 30–40% of Ukrainians) reduce folic acid conversion to its active form.

Therefore, active forms — metafolin or 5-MTHF — are more effective for most people.

How folic acid affects mood

B9 directly influences serotonin levels, so its deficiency may present as depression, anxiety, or emotional instability. Read more about another vitamin involved in serotonin regulation in the article “Vitamin B8 (inositol): not only for fertility but also for mood in autumn“.
A study in the Journal of Affective Disorders (2024) showed that supplementing 400–800 µg of methylfolate for 6 weeks improved mood in 68% of participants with seasonal depressive symptoms.

Table 2. Combinations with folic acid

Optimal doses

• Preventive: 400 mcg/day.

• For anemia, depression, or pregnancy planning: 800–1000 mcg/day.

• Active form: L-5-MTHF is absorbed 2–3 times better than regular folic acid.

FAQ

1. Can you take folic acid without a doctor’s prescription?
Yes, in preventive doses (400 mcg/day) — it is safe for most people.

2. Does it affect sleep?
Yes, indirectly through serotonin and melatonin synthesis.

3. Does it help with hair loss?
Yes, when combined with biotin and zinc, it improves nourishment of hair follicles.

4. Should you take metafolin if you don’t have an MTHFR mutation?
Yes, the active form is safe and better absorbed in any case.

5. Which foods contain folates?
Spinach, broccoli, avocado, lentils, chickpeas, eggs, liver. But up to 70% of folates are lost during boiling.

Conclusions

Folic acid is the vitamin of cellular life.
It supports energy, mood, vascular health, and tissue renewal.
In autumn and winter, when emotional load increases and the amount of greens in the diet decreases, additional B9 support is a simple yet powerful way to maintain mental clarity and physical stability.

References

1. Kim, Y. I. J Affect Disord., 2024 — “Folate status and mood regulation.”

2. EFSA, 2025 — “Dietary reference values for folate.”

3. Lurie, J. Nutrients, 2023 — “MTHFR polymorphism and folate metabolism.”

4. O’Leary, F. Nutrients, 2024 — “Comparative bioavailability of L-5-MTHF vs folic acid.”

5. WHO, 2024 — “Folate in non-pregnant adults: guidelines for public health.”