If I had a dollar for every client who came in with thinning hair and turned out to be vitamin D deficient, I could retire. It’s that common — especially in Chicago, where we get about five months of real sunlight a year.
The connection is real
Vitamin D plays a role in the hair follicle cycle. Specifically, it helps stimulate hair follicles that have gone dormant. When your levels are low, follicles can stay in the resting phase longer than they should, which means more shedding and slower regrowth.
This isn’t fringe science. Dermatologists routinely check vitamin D levels in patients with hair loss, and low levels are one of the most common findings. It’s also one of the most fixable, which is the good news.
Who’s most at risk
Anyone living above the 37th parallel — that’s basically everyone north of Virginia. Chicago sits at the 42nd. From roughly November through March, the sun is too low in the sky for your skin to synthesize meaningful vitamin D, even if you’re outside.
Add sunscreen use (necessary, but it blocks vitamin D synthesis), darker skin tones (more melanin means less conversion), and indoor lifestyles, and you’ve got a recipe for widespread deficiency. Some estimates suggest 40–50% of American adults are vitamin D insufficient.
How to know if it’s you
Get a blood test. Seriously, that’s it. Ask your doctor for a 25-hydroxyvitamin D test. Optimal levels are generally considered 40–60 ng/mL. Below 30 is insufficient. Below 20 is deficient.
Symptoms beyond hair loss: fatigue, muscle weakness, bone pain, mood changes. If you’re experiencing several of these along with increased shedding, vitamin D is worth checking.
What to do about it
If you’re deficient, your doctor will likely recommend supplementing with vitamin D3 (not D2 — D3 is better absorbed). Typical maintenance doses range from 1,000–5,000 IU daily depending on your levels. Take it with a meal that contains fat — vitamin D is fat-soluble and absorbs better that way.
You’ll also want to eat vitamin D-rich foods: fatty fish, egg yolks, fortified dairy. But realistically, if you live in Chicago, food alone probably won’t get you to optimal levels during winter. Supplementation is usually necessary.
How long until you see results
This is where patience matters. It takes about 3 months of consistent supplementation to bring levels up, and another 3–6 months after that to see visible changes in hair density. Your follicles need time to shift from resting back to active growth.
I tell clients to think of it as a 6-month commitment. If you’re expecting results in 2 weeks, you’ll be disappointed. If you’re consistent for 6 months, you’ll likely see meaningful improvement.
What we can do in the meantime
While you’re addressing the internal issue, we can help with the external. Davines Naturaltech Energizing scalp treatments stimulate follicle activity topically. Volumizing cuts and styling techniques create the appearance of fullness while your hair recovers. And honest conversation about what’s realistic — which is what we do best.
Book at Reverie if you want someone who looks at the whole picture, not just the surface.
