Food Intolerance Test (IgG Panel): Why Doctors Don’t Trust It (Video)

Transcript

Your IgG test result mostly tells you what you already eat. Surprised?

Your IgG test result mostly tells you what you already eat. Surprised?

IgG Food Test: Skip It?

Stay till the end for the one emergency sign that means don't wait.

Verdict: Skip It

Here's the thing: the verdict is pretty clear. An IgG food intolerance test is mostly a waste of money, and sometimes a risky one. A high number for wheat, milk, or eggs mostly tells you that you eat those foods regularly, not that they're making you ill. Think about it. Your immune system has met these proteins before, so it makes a note. That's normal bookkeeping, not a diagnosis.

What IgG really measures

So what does an IgG test actually measure? It measures antibodies called IgG, which your body makes when it meets a food's proteins. Eat roti and chai daily, and your body logs those foods as seen before. That's ordinary bookkeeping, not an alarm. Allergy specialists say that's a normal response, and higher levels can even mean tolerance. So the foods you eat most will nearly always show the highest numbers. That's a diary of your diet, not a diagnosis.

Why doctors don't trust it

Why don't doctors trust these tests? Three reasons. First, the result tracks exposure, not illness. Second, the NHS says home tests that claim to diagnose food intolerances aren't recommended, because there's limited evidence they're accurate. Third, the harm is real. A report that flags fifteen foods can push someone into a thin, joyless diet that misses iron, calcium, and fibre, while the real cause of their symptoms goes unchecked. That third point matters more than the money.

Flagged by one report

And this is where it gets interesting. In one report, a single IgG test flagged fifteen foods as problems. Fifteen. Imagine cutting out fifteen things from your diet based on a test that mostly measures what you eat. You'd be left with a thin, joyless menu, missing iron, calcium, and fibre, while the real cause of your bloating stays completely hidden. That's not just wasted money. That's potential harm.

Which test is which?

The IgG panel borrows credibility from the real tests. A true food allergy is fast: hives, swelling, vomiting, wheeze, and it's checked with specific IgE or a skin prick. Coeliac disease is immune damage to the gut from gluten, and the screening test is tTG IgA. Keep eating gluten until it's done, or it can come back falsely normal. Lactose intolerance is neither. That's gas, cramps, and loose stools after milk, and the best test is a diary plus a trial off and back on.

What to do instead

So what should you do if certain foods upset you? The honest route is slower, cheaper, and far more useful. Start with a two-week diary: write what you ate, roughly how much, and any symptom with the time it started. Then see a doctor, and mention weight loss, blood in stool, night-time diarrhoea, or a family history of coeliac disease. Then try one elimination at a time. Remove one suspect for two to four weeks, then bring it back.

The reintroduction trick

Now, the part most people miss. Cutting a food and feeling better proves very little, because you probably changed other habits that week too. The useful part is bringing it back. Reintroduce milk, for example, as half a cup on a calm day, then a full cup two days later. If symptoms return each time, that's worth reporting to your doctor. If they don't, you can stop avoiding it.

Lactose and gluten

Many adults in South Asia digest less lactose than they did as children. Dahi and aged cheese are often better tolerated than a big glass of milk, and smaller servings spread through the day help. None of that needs an IgG panel. Gluten is different. If wheat seems to bother you, do not quietly drop roti first. Ask for coeliac screening while you're still eating it. Going gluten-free before the test can hide the answer for good.

Children need extra care

Children need extra care with these reports. A child's diet has less room for error. Cutting milk, wheat, and eggs on the strength of an IgG report can leave a growing child short of calcium, protein, and energy. The NHS advises getting a GP or dietitian's advice before removing foods, especially for children. If your child already had a panel done, keep feeding the flagged foods they eat without trouble, and take the report to the paediatrician rather than acting on it.

The one emergency sign

Here's the one emergency sign to remember. See a doctor for unexplained weight loss, blood or black stool, night-time diarrhoea, persistent vomiting, trouble swallowing, or anaemia. But the real emergency is this: lip or tongue swelling, wheeze, or faintness after food. Call your local emergency number right away. In Pakistan that's 1122, in India it's 112. Don't stop or start any medicine because of a food test; that decision belongs to your doctor.

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Read the full guide

The full guide is on thecareonline.com. General information only, so check with your doctor for your own case.