Folic acid is an essential B vitamin your follicles use to build new hair. It works as a co-enzyme in DNA and amino-acid synthesis, which is how rapidly dividing cells—like the hair-matrix cells at the base of each follicle—copy themselves and push out new strands. (Source)
When folate is low, you don’t just feel tired; dermatologists have long reported changes in hair, skin, and nails, including thinning hair and poor-quality growth. A large review on vitamins and minerals in hair loss notes that folate’s role in nucleic-acid production likely matters for the “highly proliferative hair follicle,” and that deficiency has been linked to hair changes and premature greying in several human studies. (Source)
Women are uniquely vulnerable to subtle B-vitamin and iron issues: heavy periods, pregnancy, postpartum shifts, dieting, and vegetarian/vegan eating patterns can all strain folate status. In real-world dermatology clinics, studies in women with chronic diffuse shedding (telogen effluvium) and other hair-loss complaints frequently measure ferritin, vitamin B12, and folate, because abnormalities in these nutrients show up more often in hair-loss patients than in the general population. (Source)
A recent randomized, placebo-controlled trial in women with thinning hair tested a multi-nutrient supplement containing biotin, folate, and other micronutrients. After 168 days, women on the supplement had ~10% higher hair density, while the placebo group slightly worsened; 80% of treated women improved versus 47% on placebo, and self-rated shedding, fullness, and breakage also improved. (Source) Folic acid wasn’t acting alone, but this kind of data supports the strategy Locklab uses: correcting common, low-grade nutrient shortfalls alongside powerful hair medications.
Homocysteine is a sulfur-containing amino-acid byproduct. When it builds up, it can damage the inner lining of blood vessels (the endothelium), stiffen arteries, and reduce micro-circulation—exactly what you don’t want in a scalp trying to regrow hair. A 2024 case-control study in androgenetic alopecia (pattern hair loss) found that people with AGA had higher blood homocysteine levels than controls, and that experimentally raising homocysteine in mice directly inhibited hair growth and lowered hair-growth markers like Ki-67 and VEGF in the follicles. (Source)
Folic acid is one of the body’s main tools for converting homocysteine into beneficial amino acids. Multiple randomized trials and meta-analyses in cardiovascular patients show that daily folic acid (typically 0.4–5 mg) lowers plasma homocysteine by roughly 20–25% and often improves flow-mediated dilation (a standard measure of endothelial function and blood-vessel responsiveness). (Source) While these studies look at heart and large-artery health—not hair directly—the same biology applies to the tiny vessels feeding each follicle. By helping keep homocysteine in check and supporting healthier endothelium, folic acid complements minoxidil’s vasodilator effect to maintain better blood flow and nutrient delivery to your scalp.
Each Locklab Women’s tablet contains 2.5 mg of vitamin B9 (folic acid)—a dose in the range used in vascular and homocysteine-lowering studies, chosen by our medical team to support vigorously dividing hair-matrix cells and healthy micro-circulation. It isn’t meant to treat severe folate deficiency on its own, but to help close the gap for women whose everyday diets, hormones, and life stages make them more vulnerable to subtle, hair-relevant shortfalls.
Selected clinical evidence on folate & hair / circulation
The goal of including folic acid in the tablet is simple: give your follicles the cellular building blocks and vascular support they need, while minoxidil handles the heavy lifting on growth activation.
