◆ IDUN Journal

What Actually Causes Hair to Thin — and What Can Be Reversed

By Siu Lie Tan, Founder · 6 min read

Most thinning is not the end of a follicle’s life. It is a pause — and pauses can end.

Hair thinning rarely arrives as a single event. It gathers quietly — more strands in the brush, a part that widens by a millimetre, a ponytail that feels thinner in the hand. Understanding why matters, because the cause largely decides what is reversible.

Shedding is not the same as thinning

Losing 50 to 100 hairs a day is normal; hair is always cycling. Two very different things get called "hair loss." The first is increased shedding — more hairs than usual entering the resting and falling phases at once. The second is miniaturisation — follicles that survive but produce progressively finer, shorter, weaker hairs each cycle. Shedding is usually a response to a shock; miniaturisation is usually hormonal and gradual. The good news is that both, caught in time, can respond.

The three patterns worth knowing

• Sudden, diffuse shedding. Often two to three months after a physical stress: illness, surgery, childbirth, a crash diet, a thyroid swing, or acute stress. This is telogen effluvium — a large group of follicles pushed into rest at once. It is typically highly reversible once the trigger passes and the scalp is supported.
• Gradual thinning at the hairline or crown. Genetic, tied to the follicle’s sensitivity to the hormone DHT, with each cycle producing finer hair. This is the slow miniaturisation of pattern thinning. Caught early, it can often be partially reversed; left long, follicles eventually close.
• Rapid loss following acute medical exposures such as chemotherapy or radiation, which interrupt the fast-dividing cells of the follicle directly.

Nutrient gaps — iron, zinc, protein, vitamin D and the B-vitamins — and autoimmune conditions can also interrupt the cycle by starving the follicle of the blood supply and building blocks it needs to grow.

How to read your own scalp

There is a simple, encouraging test. Look closely, in good light, at the thinning area.

If the follicles are still open and you can see fine hair tracks, the structure is intact — it has simply paused.

Open follicles with visible tracks mean the machinery is present and waiting; this is the situation most likely to recover. If what remains is fine, colourless "peach fuzz," the follicle is miniaturising under hormonal pressure — still worth acting on, and often partially reversible, but the window matters. Smooth, shiny scalp with no visible follicle openings suggests the follicle has closed, where regrowth is unlikely.

What genuinely helps a follicle recover

A follicle is a small, demanding organ. To complete its growth phase it needs three things: a steady blood supply carrying oxygen and nutrients, a calm environment free of chronic inflammation and oxidative stress, and time — support delivered consistently across a full cycle, not in bursts.

This is the logic behind 001. Its botanical oils are rich in antioxidants and anti-inflammatory compounds that lower the oxidative stress a struggling follicle sits in, while the act of massaging it in stimulates local circulation — the delivery system the follicle depends on. In IDUN’s testing, consistent use raised hair density by an average of 10.71% in four weeks. Not a miracle; a follicle given what it was missing, finishing the job it already knew how to do.

If your scalp still shows open follicles, the most useful thing you can do is start early and stay consistent. A paused follicle responds to patience far better than to intensity.

This article is for general educational purposes and is not medical advice. IDUN's cited results (+18.04% skin elasticity, +10.71% hair density at four weeks) reflect IDUN's own product testing. For a medical concern, consult a qualified professional.