The Supplement Audit: Seven Questions Before You Take Anything

Food first, in the evidence, not as a slogan

Before you buy

1. What is it for, and in whom was that measured? Marketed outcomes and trialled outcomes are often not the same thing. One trial of a popular mitochondrial-support ingredient, in adults aged 65 to 90, missed both of its primary endpoints, a six-minute walk test and a direct measure of muscle energy production. A secondary measure did improve. Several of the trial's authors held a financial stake in the company that funded it, disclosed in the paper itself. The useful habit here is to ask, whenever you see a benefit quoted for an ingredient, whether it was the outcome the trial set out to test or one found along the way.
2. Which gap is it actually filling, and have you measured the gap? Supplement use in Australia rises with age and is highest in the 50 to 64 bracket. That survey asked what people took in the day before the interview, so it is a snapshot rather than a measure of long-term habit. Either way, it tells you a lot of people your age are buying. It does not tell you any of them measured a shortfall first.
3. What does the label say was actually checked? Every legal product carries an AUST number. What it starts with tells you how much examination happened before it reached the shelf. More on this below, because it is the single most useful thing in this guide.

What's already in your system

4. Are you already taking this ingredient somewhere else? A multivitamin, a sleep blend and a B-complex can easily share an ingredient without you noticing. Vitamin B6 is the clearest Australian example. It can damage nerves, and above a certain daily amount Australian products must carry a warning telling you to stop taking it and see your healthcare practitioner as soon as possible if you get tingling, burning or numbness. The warning names no part of the body, and nor should you: the TGA's own description says the symptoms are usually, though not only, in the hands and feet. Harm has occurred in people taking more than one B6-containing product without realising it was in both, often because one of them was sold as something else, such as a magnesium supplement.
5. What could it interact with, and has the person who can see your full list seen this too? Five categories are worth knowing before you ask a pharmacist, not instead of asking one.

Five categories worth knowing

• Anything that affects blood clotting. A systematic review of warfarin interactions found 78 herbs, foods or supplements reported to interact with it, with some linked to bleeding events. This is specific to warfarin, not blood thinners generally.
• Anything that changes how your liver clears medicines. St John's wort is the established case and the one most people do not realise is powerful: it speeds up the clearance of a long list of prescription medicines, making them weaker, with nothing on the label to tell you. Echinacea has also been reported to do this, on weaker evidence.
• Minerals taken close to a medicine that needs an empty stomach. Calcium, iron, coffee and fibre have all been shown to reduce absorption of thyroid medicine when taken too close together. The answer is usually about spacing rather than stopping, which is a conversation with a pharmacist, not a change to make on your own.
• Supplements that are pharmacologically the same class as a prescription medicine. Red yeast rice is the clearest case: a European food safety review found the active compound it contains, chemically identical to a statin, carries a safety risk at levels far below what is typically sold, including to muscle and liver. This is a European finding, not an Australian regulatory position.
• Liver load, including from products marketed as gentle. In US data, the share of liver-injury cases attributed to herbal and dietary supplements rose noticeably over a decade, and botanicals such as turmeric, green tea extract and ashwagandha are now taken by an estimated 15 million-plus US adults, most often by people in their 40s, 50s and 60s. This is US data, included because nothing equivalent has been published in Australia.

The symptoms worth knowing, whatever you take

Set this before you start, and know your stop trigger

6. Before you start: what will change, how will you measure it, and by when? The honest answer to "how would you know it worked" is that you cannot tell, after the fact, by how you feel. The cleanest evidence for this comes from a trial of people who had stopped taking a statin because of side effects. Given unlabelled months of the real drug, a placebo, and nothing at all, they reported feeling worse on both the drug and the placebo, and no better on nothing, with almost no difference between the drug and the dummy pill. Whether someone felt a symptom start, or felt it ease off when they stopped, did not reliably tell them which one they had actually been taking. That trial tested a drug's side effects, not a supplement's benefit, but the lesson about how unreliable your own body's reporting is travels in both directions. One thing it is not: a reason to doubt a side effect you are having from a prescribed medicine. If you think a medicine is causing you a problem, that is a conversation with your doctor, not a reason to stop taking it. The fix is to name one outcome you actually care about, decide how you will record it, not recall it, and set a date, before you start. Anything short of that and you are measuring expectation, not the supplement.
7. When do you stop, and what is the trigger? Vitamin B6 again supplies the clearest Australian example: a labelled warning that tells you exactly when to stop and who to see. Most products will not spell this out as plainly. Decide your own trigger before you start: a side effect, the date from question 6 passing with nothing to show, or a change in your own health or medicines.

What the AUST number tells you, and what it doesn't

Who to ask before you start

• You take regular prescription medicines, of any kind.
• You have surgery, a procedure or a dental extraction coming up. Several common supplements affect bleeding and anaesthetic, and surgical teams routinely want to know well beforehand.
• You are pregnant, breastfeeding or trying to conceive.
• You have liver or kidney disease.
• You are having treatment for cancer.

If you take regular prescription medicines

Before you use AI: keep it safe

• Store your supplement list somewhere private, not in a shared drive or a long email thread.
• Before you paste anything in, turn off the use of your conversations for training. ChatGPT: Settings, Data controls, Improve the model for everyone. Claude: Settings, Privacy, Help improve Claude. Gemini: Activity, Keep Activity. This applies to new chats only, not ones you have already had.
• Leave your name, date of birth and any identifying details out of what you paste in.
• Australia's privacy regulator advises against entering personal information, especially health information, into publicly available AI tools. Treat that as the default.

Or let your AI organise the list before you see your pharmacist

I am going to give you a list of everything I take: supplements, vitamins and over-the-counter
products, with the AUST number from each label where I have it. Organise this into one page for
my pharmacist or GP.

1. Build a simple table: product name, what it is for (in my own words), AUST number, how often I
   take it.
2. Flag anything I have listed more than once under a different name, so I can check whether it is
   the same ingredient.
3. List anything missing an AUST number, so I know to check the label again.
4. Do not tell me whether anything is safe, whether it interacts with anything, or whether I should
   keep taking it. That is a question for my pharmacist or GP, not for you.

Keep it to one page.

Keep in mind