Vitamin deficiency symptoms: what Australians are actually low in
Every list of vitamin deficiency symptoms says roughly the same things. Tired. Foggy. Brittle nails. Low mood. Catching everything going around. I have read a lot of them, and not one tells you the thing that would actually help, which is how likely any of it is to be true for you, in Australia, this month.
The symptoms are real. I am not going to tell you that you feel fine. What I will tell you is that a symptom list cannot say which nutrient, because nearly every symptom on it belongs to five other things as well.
There is a better answer, and almost nobody writing about this uses it. Australia takes blood and urine from a random sample of its own population and measures what is in it. The most recent round ran from January 2022 to April 2024, with 7,479 people, and the results came out in March 2025.
It is more interesting than the lists, because it disagrees with them.
The short version
- Australia's national survey measures five nutrients: iron, folate, vitamin B12, vitamin D and iodine. Magnesium, zinc, selenium, omega-3 and choline are not measured at all, so there is no Australian figure for any of them.
- Vitamin D is the genuinely common one. One in five adults (20.6%) came back deficient, and the number moves with the calendar: 15.5% in summer, 26.1% in winter, and 45.7% in Tasmania in winter.
- Low B12 and low folate are rare here. The average adult sat at 391 pmol/L for B12, against a deficiency cut-off of 150.
- Only 3.3% of adults fell under the survey's iron cut-off, but that cut-off is 15 micrograms per litre. An Australian GP guide describes 30 as the level that reliably picks up iron deficiency, and most labs flag somewhere between 15 and 25.
- Iodine is quietly drifting down. The median for women aged 16 to 44 fell from 121 to 101 micrograms per litre between the two surveys.
The vitamin deficiency symptoms everyone lists, and what they can actually tell you
Here is the standard list, more or less unchanged from site to site: fatigue, brain fog, hair loss, brittle nails, low mood, poor concentration, getting sick often, bruising easily, cracks at the corners of the mouth, pins and needles.
Every one of those is real. Every one of them also turns up in iron deficiency, in an underactive thyroid, in perimenopause, in coeliac disease, in sleep apnoea, in blood sugar that swings, and in five months of broken sleep with nothing wrong at all.
So the list is not wrong. It is just not a test.
If you want the plain-English version of any single nutrient, Healthdirect keeps a page for each one, from iodine and iron through to zinc. What none of those pages can do, and what the rest of this article is about, is tell you which one is likely to be your problem.
If any symptom appeared on only one nutrient's list, I would use symptom lists in clinic. They do not, so I do not. A list tells you something is worth checking, which is useful, and it is not the same as knowing what. That gap is the one I wrote about in why you can be exhausted with normal bloods.
What Australia has actually measured, and what it has never measured at all
The National Health Measures Survey is the biomedical part of the Australian Bureau of Statistics' big health survey. People give blood, urine or both, and a laboratory measures them. The 2022 to 2024 round collected samples from 7,479 people aged five and over.
Here is the entire nutrient list it measured: serum ferritin, soluble transferrin receptor, C-reactive protein, haemoglobin, serum folate, serum vitamin B12, serum 25-hydroxyvitamin D, and iodine, sodium and potassium in urine.
Read it again and notice what is missing. No magnesium. No zinc. No selenium. No omega-3. No choline. No vitamin C, no B6.
That matters, because that is close to a list of the nutrients most often described online as widespread Australian shortfalls. When a page tells you magnesium deficiency is a national epidemic here, ask where the national figure came from. There is not one.
I am not saying nobody in this country is short on magnesium. I am saying any percentage attached to it came from somewhere other than a measurement of Australians, which is worth knowing before you spend money on the back of it.
Vitamin D is the genuinely common one, and it moves with the season
One in five Australian adults, 20.6%, had a vitamin D deficiency in the 2022 to 2024 survey. Deficient there means a blood 25-hydroxyvitamin D under 50 nmol/L. A decade earlier, in the 2011-12 round, the figure was 23.8%, so it has improved a little.
Two things surprise people. The first is age: deficiency was highest in the 18 to 29 group at 29.2%, and lowest in the over-65s. The second is the calendar. Nationally, 15.5% of adults were deficient in summer and 26.1% in winter, and by state the gap opens right up.
If you live in Hobart or Melbourne, the month you have the test in is not a detail. It is close to half the answer.
The biggest trial we have run on it, and the question it does not answer
Australia ran one of the largest vitamin D trials in the world. The D-Health Trial gave 21,315 Australians aged 60 and over either 60,000 IU of vitamin D or a placebo, once a month, for five years, and followed them for a median of 5.7 years.
It found no reduction in deaths. The hazard ratio for all-cause mortality was 1.04, with a confidence interval running from 0.93 to 1.18, which is the statistical way of saying nothing happened.
Then look at who was in it. In blood taken during the trial, the placebo group averaged 77 nmol/L, comfortably above the 50 nmol/L line. The trial topped up people who mostly were not low, and the authors' own conclusion was that this dosing regimen might not be appropriate in people who already have enough.
That is not an argument against knowing your number. It is an argument against assuming the number is the answer.
With iron, the number matters more than the word normal
This is the part I most want you to take away, because it changes what you say at the GP.
In the survey, 3.3% of Australian adults had a serum ferritin under the cut-off used, and women were six times more likely than men to be under it: 5.6% against 0.9%.
That reads as reassuring until you look at the cut-off, which is 15 micrograms per litre, the World Health Organization's population threshold. A practical guide published in the RACGP's own journal in May 2025 puts it differently: a serum ferritin under 30 has high sensitivity and specificity for iron deficiency, while most laboratories use a lower cut-off range of 15 to 25.
So there is a band, roughly 15 to 30, where a result lands inside the reference range, gets reported back as normal, and would still be called iron deficiency by that guide.
Now look at where Australian women actually sit.
The pattern is hard to unsee. Women aged 25 to 44 average 61 and 64. Men the same age average 151 and 180. Not until after 55, when periods stop for most women, does the female average reach territory men have been in since their early twenties.
Which is why "your iron came back normal" is the sentence I hear most often and trust least. Ask for the number.
What I see in clinic. The version I meet most often is a woman in her early forties carrying a bag of supplements, three of which are for nutrients nobody has ever measured in her, and a set of bloods from eighteen months ago whose numbers she has never seen.
So we get the numbers. Reasonably often the ferritin is sitting at 22 or 26, inside the laboratory range, reported back as normal, and nobody raised it because nothing was flagged.
Sometimes that is the whole story and sometimes it is not. But it is a real measurement of her, which is more than any symptom list can offer.
Iodine is the quiet one, and it is drifting the wrong way
Iodine gets almost no attention, and it is the one that is moving.
Between the two surveys the median urinary iodine for Australian adults fell from 124 to 112 micrograms per litre. For women aged 16 to 44 it fell from 121 to 101. The population is still classed as sufficient, because the threshold is a median under 100, but 101 is not much of a margin. For women aged 25 to 34 the median was 87, under the line, with more than one in five individual readings under 50. The range recommended during pregnancy is 150 to 249.
One caveat, and it is a real one. Urinary iodine moves with what you ate yesterday, which is why the threshold is defined as a population median rather than an individual result. Your own reading on one day tells you very little. The population trend tells you a lot.
Here is the practical part, and it never makes the symptom lists. Since 2009, Australian bakers have had to use iodised salt in bread, under Standard 2.1.1 of the Food Standards Code. All bread, with two exceptions: organic bread, and bread mixes for making bread at home. So if you have cut bread out, or you only buy organic loaves, you have quietly stepped around the main thing that was doing this job for the population.
If this sounds like you, this is what to ask about
Five patterns I meet often, and what the national numbers say about each one. None of this is a diagnosis. It is what I would want looked at first.
| The pattern | What the national numbers say | What to ask your GP about |
|---|---|---|
| Tired, breathless on stairs, heavy periods, waking at 3am | 5.6% of Australian women fall under a ferritin of 15 micrograms per litre, and the band from 15 to 30 comes back reported as normal | Iron studies with the actual ferritin number, plus a full blood count |
| Flat and achy every winter, living south of about Sydney | Winter deficiency runs at 26.1% nationally, 32.2% in Victoria and 45.7% in Tasmania | Whether you meet one of the eleven conditions on Medicare item 66833, and what a vitamin D test costs if you do not |
| Vegetarian or vegan for years, pins and needles, memory slipping | B12 deficiency is uncommon across the population, but the survey did not break the figures down by diet | Vitamin B12 and folate, and mention how long you have eaten this way |
| Off bread, or only buying organic loaves, and thinking about a pregnancy | The median for women aged 16 to 44 has fallen to 101, against the 150 to 249 range recommended in pregnancy | Your iodine intake, and whether a supplement makes sense for you |
| Taking magnesium for months and nothing has shifted | Magnesium is not measured in the national survey, so there is no Australian rate to compare yourself against | What else could account for the symptom you started taking it for |
What to do this week, before you buy anything
None of this costs money.
- Find your last iron studies and read the ferritin number rather than the word beside it. Anything between 15 and 30 is worth a conversation rather than a shrug.
- Know the vitamin D rule before you ask for the test. Medicare item 66833 rebates it only for one of eleven listed situations, including signs of osteoporosis or osteomalacia, malabsorption, deeply pigmented skin or a chronic lack of sun exposure, certain medications, and chronic renal failure. Being tired is not on the list. You can still have the test, you just pay for it, and the schedule fee is $30.05. There is more on what Australian labs will and will not do without a referral in this piece on blood tests without a GP referral.
- If you are having vitamin D done anyway and you live in the southern half of the country, note the month. February and August are two different questions.
- Keep a two-week note: what time you wake, how you feel at 11am and at 3pm, your period if you have one, and how much sleep you got. Take it in with you. It is worth more than any symptom list.
And before you buy a panel, ask yourself:
- What would I do differently once I had the result?
- Has anyone checked the ordinary things first, iron, B12, folate, thyroid and vitamin D?
- Is the nutrient I am worried about one that Australia has ever measured?
- Who is going to read the result with me, and what do they sell?
- If it all came back completely normal, would I believe it?
That last one is not a trick question. A test you will not believe is an expensive way to stay in the same place.
Where a panel helps, and where it does not
A panel is useful when it answers a question you have already narrowed down, and when someone reads it beside your history, your medications and the bloods you already have. That is the whole of it. I have written the longer version of that in what functional testing is and is not, and the current panels sit on the testing page.
What a panel cannot do is tell you which of your symptoms it explains. That is a judgement made by a person with the rest of your picture in front of them.
Start with your GP, especially if a symptom is new, getting worse, or frightening you. If ongoing fatigue and fog are the reason you are reading this, the fatigue and brain fog page sets out how we work through it.
If you take one thing from this, make it the ferritin number. It costs nothing to look up, it is the one most often waved through as normal, and of everything on this page it is the number I would most want you to know.
Not sure which of these applies to you?
If you have been going round in circles on this, a short call is usually enough to work out whether anything here is worth chasing, and in what order. Nothing is sold on that call.
Book a free 15-minute callFifteen minutes, no cost, and you can bring any results you already have.
Common questions
What is the most common vitamin deficiency?
In Australia, vitamin D. The National Health Measures Survey found 20.6% of adults deficient in 2022 to 2024, which is one in five. On the survey's other nutrient measure, 17.4% of adults had a urinary iodine under 50 micrograms per litre, although for iodine that is a population signal rather than an individual result. Low B12 and low folate are both uncommon here.
What are symptoms of low vitamin levels?
The usual list is fatigue, brain fog, low mood, poor concentration, hair loss, brittle nails, frequent infections, bruising easily, cracks at the corners of the mouth and pins and needles. They are real symptoms, but they overlap almost completely with iron deficiency, thyroid conditions, perimenopause, coeliac disease, sleep apnoea and simple sleep debt. They tell you something is worth checking, not which nutrient it is.
Why is everyone so low on vitamin D?
Mostly season, latitude and how we spend our days. Australian deficiency runs at 15.5% in summer and 26.1% in winter, and in Tasmania it reaches 45.7% in winter. It is also highest in younger adults, 29.2% in the 18 to 29 group, which surprises people who assume it is an older person's problem.
What are the 10 signs of low vitamin D?
There is no set of ten signs that belongs to vitamin D alone, which is the honest answer. Tired, achy, low, sore muscles and poor sleep all appear on the lists, and all of them have other and more common explanations. The only way to know your vitamin D level is to measure it, and in Australia the month you measure it in changes the answer.
What are signs of low B12?
Pins and needles, numbness, poor memory or concentration, a sore red tongue, unsteadiness and fatigue. Low B12 is uncommon in Australia at a population level, with an average adult level of 391 pmol/L against a deficiency cut-off of 150. It is worth checking if you have eaten a vegetarian or vegan diet for years, if you take certain long-term medications, if you have a gut condition or have had gut surgery, or if you are older. Your GP will know which of those apply to you.
What are the three most common vitamin deficiencies?
Of the five nutrients Australia measures nationally, vitamin D is the clear first at 20.6% of adults deficient. Iodine comes next on the survey's own measure, with 17.4% of adults under 50 micrograms per litre in urine, though that is a population signal rather than an individual result. Iron is third, at 3.3% under a ferritin of 15, and 5.6% of women. Folate and B12 deficiency are both rare. Magnesium, zinc and omega-3 are not on that list because they have never been measured in a national Australian sample.
Sources
- Australian Bureau of Statistics. National Health Measures Survey, 2022-24. Released 31 March 2025.
- Australian Bureau of Statistics. National Health Measures Survey methodology, 2022-24. Sample of 7,479 respondents; vitamin D deficiency defined as under 50 nmol/L.
- Australian Bureau of Statistics. Australian Health Survey: Biomedical Results for Nutrients, 2011-12. The earlier round the 2022-24 figures are compared with.
- Neale RE, Baxter C, Romero BD, et al. The D-Health Trial: a randomised controlled trial of the effect of vitamin D on mortality. Lancet Diabetes Endocrinol 2022;10(2):120-128.
- Patel S. Ferric carboxymaltose: a practical guide on the administration of iron infusions in general practice. Australian Journal of General Practice 2025;54(5), RACGP.
- Department of Health and Aged Care. Medicare Benefits Schedule item 66833, 25-hydroxyvitamin D quantification.
- Food Standards Australia New Zealand. Iodine fortification. Mandatory since 2009 under Standard 2.1.1.
- Healthdirect Australia. Vitamin and mineral deficiency.
Important: This article is general information written by a clinical nutritionist. It is not medical advice and does not replace care from your GP or another qualified health professional. Functional testing does not diagnose, treat, cure or prevent any condition, and results are best interpreted alongside your symptoms, history, medications and supplements.
Written and reviewed by Georgina Waugh
Clinical Nutritionist, BHSc Nutritional Medicine
Last updated: 22 June 2026
Sources reviewed: the ABS National Health Measures Survey, the RACGP's journal, the D-Health Trial, the Medicare Benefits Schedule and Food Standards Australia New Zealand