By Kirstie Vesseur, Registered Clinical Nutritionist (CNA), Legacy Nutrition, NZ and Australia.
You pull a handful of hair from the shower drain and think, surely that is more than last month. Your ponytail feels thinner. You have started noticing your part in photos.
Hair loss is one of the most distressing symptoms women bring to me, and it is often brushed off. Shedding usually has a reason. Hair follicles are sensitive to what is going on inside the body, so they can be one of the first places to show strain. Here is what I look at, and what you can do.
How hair growth works
Each hair follows a cycle: a long growth phase, a short transition, then a resting phase before it sheds. After a shock to the body, more follicles can move into the resting phase at once. This is called telogen effluvium. The extra shedding usually starts two to four months after the trigger, which is why it often seems to come out of nowhere.
Common triggers include:
illness or a high fever
surgery
a major stressful event
childbirth
rapid weight loss or crash dieting
stopping the combined oral contraceptive pill
some medicines (if you think a medicine is involved, talk to your GP or pharmacist before stopping or changing it)
Once the trigger has passed, this type of shedding usually settles within about six months.
Why is my hair falling out? The usual suspects
Low iron stores
Low ferritin (your iron stores) is common in women with hair shedding, and studies show women with hair loss tend to have lower ferritin. What research has not yet shown is that iron supplements regrow hair in everyone. Still, if your iron is low, it is worth correcting for your energy and overall health, not only your hair. My article on why your ferritin might be low goes into the causes.
Thyroid
Both an underactive and an overactive thyroid can cause diffuse thinning across the scalp. A standard check often includes only TSH. If your hair is thinning along with tiredness, feeling cold or weight changes, it is reasonable to ask your GP about free T4 and thyroid antibodies (TPO) as well. Read more in thyroid health for women.
Hormones
Midlife changes: female pattern hair loss, where hair gradually becomes finer and thinner, especially along the part and crown, becomes more common after menopause.
PMOS (formerly PCOS): androgens such as testosterone may play a part for some women, and hair thinning can be more marked with PMOS. That said, most women with female pattern hair loss have normal androgen levels.
Coming off the pill: some women notice shedding a few months after stopping.
Not enough protein or energy
Hair is made mostly of keratin, a protein. Crash diets and long-term under-eating are recognised triggers for shedding.
Other nutrients
Lower zinc and vitamin D levels have been linked with some types of hair loss in observational studies. The evidence for B12 and folate is less clear. Biotin deficiency is uncommon, and there is no good evidence that biotin supplements help hair if you are not deficient.
Gut absorption
Coeliac disease damages the part of the small intestine where iron is absorbed, and acid-lowering medicines can reduce iron absorption. This is how you can eat well and still run low. If your iron keeps dropping despite good intake, talk to your GP about why.
What is worth testing
If your hair is shedding, these are reasonable tests to discuss with your GP:
full blood count and iron studies (including ferritin)
TSH, free T4 and thyroid antibodies
B12 and folate
vitamin D
zinc
if you have signs such as acne, irregular cycles or extra facial hair: testosterone, SHBG and free androgen index
See your GP or a dermatologist promptly if hair loss is patchy, comes with scalp redness, scaling, itch or pain, or you are losing eyebrows or body hair, or if it comes with other symptoms such as unexplained weight loss, fever, a racing heart or ongoing fatigue. These can point to conditions that need medical treatment.
How nutrition can help
Be patient. Because of the hair cycle, it usually takes three to six months before you see less shedding, and longer before thickness improves.
Protein at every meal
Adult women need at least 0.75 g of protein per kg of body weight a day, about 46 g for many women. A practical target is 20 to 30 g at each main meal. That looks like:
2 to 3 eggs plus a pottle (170 g) of Greek yoghurt at breakfast
a palm-sized piece (100 to 120 g) of fish, chicken or red meat at lunch or dinner
150 g of firm tofu or 1 cup of cooked lentils if you eat plant-based (about 18 to 20 g, so add pumpkin seeds, yoghurt or edamame)
Breakfast is often the meal that falls short.
Iron and zinc foods
lean red meat two to three times a week
mussels, sardines and eggs
pumpkin seeds, lentils and chickpeas
vitamin C foods (capsicum, kiwifruit, citrus) with plant iron sources
tea and coffee kept at least an hour away from meals, as they reduce iron absorption
Supplements, only when tests show a need
Iron: please test first, because too much iron is harmful. Your GP will set the dose. Iron bisglycinate is widely used and may cause fewer gut side effects (most trial evidence is in pregnancy). Small studies found iron taken every second day was absorbed better than daily dosing, so ask your GP whether alternate-day dosing suits you.
Zinc: if your zinc is low, 15 to 25 mg of elemental zinc a day with food (for example zinc picolinate or citrate) for two to three months is a common short-term approach. Keep your total from all supplements under the 40 mg a day upper limit, as long-term high zinc can lower copper.
Vitamin D: if your level is low, your GP can prescribe vitamin D3 (colecalciferol) at a dose based on your result. In New Zealand this is often a 1.25 mg (50,000 IU) capsule taken once a month. Do not exceed 80 mcg (3,200 IU) a day from over-the-counter supplements without medical advice.
Biotin: not recommended unless deficient. If you take it, tell your GP and the lab. It can distort some blood test results, including thyroid tests, so ask your GP or lab how long to stop it beforehand (often at least 8 hours, or up to 3 days for high-dose hair supplements).
Check with your GP or pharmacist before taking any supplement if you take medication, are pregnant or breastfeeding.
Thyroid-friendly foods
One or two Brazil nuts a day provide selenium. Content varies widely between nuts, so more is not better, and too much selenium can itself cause hair loss. Seafood, eggs and dairy provide iodine. Check with your GP before taking iodine supplements if you have Hashimoto's or another thyroid condition (pregnancy advice differs, so follow your midwife or GP).
Steady blood sugar for hormone balance
For PMOS and midlife hormone changes, build meals around protein and fibre: vegetables, legumes, whole grains and 1 to 2 tablespoons of ground flaxseed a day. Pair carbohydrates with protein to avoid big sugar swings. The 2023 International PCOS Guideline says inositol could be considered based on personal preference, but the evidence is limited and no specific dose can yet be recommended.
Lifestyle factors
Stress: a major stressful event is a well-known trigger for shedding. Small daily practices, such as a walk outside or slow breathing, can help you manage ongoing stress.
Sleep: aim for 7 to 9 hours with a consistent rhythm.
Gentle hair care: go easy on heat styling, harsh treatments and tight hairstyles while you recover. Scalp massage feels lovely, but evidence is limited to a couple of small studies.
Frequently asked questions
How long does it take for hair to grow back?
Once the trigger is addressed, shedding often eases within a few months. New growth takes longer to show, and a visible change in thickness usually takes six months or more.
Will biotin help my hair?
Only if you are deficient, which is uncommon. Iron, protein, thyroid and hormones are more likely to be the issue.
Is hair loss just part of getting older?
Hair does change with age and hormones, but sudden or significant shedding is worth investigating at any age.
Where to start
If your bloods have been called normal but your hair is still thinning, a closer look is worthwhile.
Know what your blood tests are really telling you
Get The New Zealand Optimal Ranges Guide to see how your results compare with optimal ranges, or use the free Check Your Bloods tool.
Want help with your own plan? Book your free 30 minute assessment
This article is general education, not personal medical advice. Please talk with your GP before starting supplements or changing medication.
References
Hughes EC, Saleh D. Telogen effluvium. StatPearls, accessed November 2026. ncbi.nlm.nih.gov/books/NBK430848
Almohanna HM et al. The role of vitamins and minerals in hair loss: a review. Dermatology and Therapy, 2019. pmc.ncbi.nlm.nih.gov/articles/PMC6380979
Treister-Goltzman Y, Yarza S, Peleg R. Iron deficiency and nonscarring alopecia in women: systematic review and meta-analysis. Skin Appendage Disorders, 2022. karger.com
Hair loss, temporary or abnormal. Healthify He Puna Waiora, accessed November 2026. healthify.nz
Female pattern hair loss. DermNet, accessed November 2026. dermnetnz.org
Stoffel NU et al. Iron absorption from supplements is greater with alternate day than consecutive day dosing in iron-deficient anaemic women. Haematologica, 2020. haematologica.org
Nutrient Reference Values for Australia and New Zealand: zinc. NHMRC, accessed November 2026. eatforhealth.gov.au
Vitamin D: an update. bpac nz, accessed November 2026. bpac.org.nz
