Why I Use Ginger When the Stomach Turns

Ginger is an ingredient you keep in the kitchen. Perhaps that is why, when I mention that ginger goes into a herbal prescription, I often get a "well, that's hardly anything" in reply.

I see this ingredient a little differently. When it comes to nausea, ginger belongs among the materials with a fair amount of human research behind them. And what it does in the body is known fairly specifically as well.

Today let me follow this one common root through.

Where does the signal to vomit come from

First, let me look at how vomiting happens in the first place.

When the lining of the stomach is irritated, serotonin is released. When that substance binds to a receptor in the gut's nerves called 5-HT3, the signal travels up to the brain and becomes the order to vomit. Among the anti-nausea drugs given at hospital during chemotherapy, there are ones that block exactly this receptor.

The compounds that give ginger its pungency block the same receptor. They are called gingerol and shogaol.

The same compounds bind elsewhere too. They act on the channel that chilli's pungency opens — called TRPV1 — and on TRPA1, which the sharpness of cinnamon or mustard opens. These channels are not only on the tongue but in the lining of the digestive tract, at sensory nerve endings, and on the vascular side. One compound switches on a different thing in each of several places.

But the manner of it differs. The hospital drug takes the seat serotonin would sit in before it can get there. The ginger compounds, on the other hand, bind at a different site and lower how far that receptor opens at all. Not blocking the door, but making the door open less. This has been confirmed in human receptors and in human gut tissue.

It is the same destination by a different road, and I find passages like this interesting. The body has several ways of doing one thing, and the plant, it turns out, found a different one among them.

The speed at which the stomach empties changes too

There is one more thing ginger does. It speeds up how fast the stomach empties.

In a study of 24 healthy adults, gastric emptying time was nearly halved in the group that took ginger. Since food sitting in the stomach for a long time can itself produce nausea, this becomes another route.

That said, in the same study the digestive symptoms themselves did not change clearly. The stomach emptying faster and the stomach feeling better are not yet the same story. The route is visible, and that is as far as it goes.

Dried ginger is a different material

Korean medicine has long used fresh ginger and dried ginger (geon-gang) separately. The places they are used and the actions expected of them both differ.

Learning this distinction, I wondered: why go to the trouble of splitting the same root in two?

Measure the compounds and they have in fact changed. Drying ginger turns gingerol into shogaol. But it is not that the harder you heat it the more converts. The most is produced at a moderate temperature, and hotter than that it actually decreases. The conversion needs moisture, and if it is too hot the water goes off first.

This is why ginger is dried slowly in the shade. Not spread out in the sun, not rushed dry over a fire. While the moisture leaves gradually, the conversion is given time to happen. How the old practitioners arrived at this method, we cannot know. But measure the compounds now, and that method leaves the most shogaol.

So dried ginger is not simply ginger that has dried; it is a material whose compound composition has changed. There is no way the old practitioners knew this chemistry. They noticed with the body that the uses differed and set the two apart, and chemistry later came along and supplied the reason.

Passages like this are the pleasure of studying this medicine. Though I have yet to see a study comparing the two head to head in people to see which is better for nausea.

How far has it been confirmed in people

The area with the most data is morning sickness. There is an analysis pooling twelve studies of ginger for nausea and vomiting in pregnancy, covering 1,278 pregnant women. The result was that nausea improved compared with placebo. The evidence was weak, though, for saying that the number of actual vomiting episodes fell as well.

For nausea during chemotherapy, results split from study to study. There are studies showing improvement and studies showing no difference.

To sum up: there is evidence for the feeling of nausea, and beyond that, not yet. I take it to be a material of about that order, and use it accordingly.

First I look at where the nausea comes from

I do not try to solve anything with ginger alone. Nausea comes from the stomach sometimes, from the ear sometimes, from tension sometimes. I look first at where it is coming from.

But knowing the route of these compounds shows me where they belong. Someone whose stomach empties slowly and someone whose signal rises too readily on irritation have different places to be mended. (Same illness — so why treat each person differently?)

If you are pregnant, or taking a blood-thinning medicine, please tell me in advance whatever it is you are taking. Even if it is something from the kitchen. (May I take herbal medicine while pregnant or breastfeeding?)

And if there is blood in what you bring up, if you cannot keep even water down, or if the vomiting comes with a severe headache — this is a different matter. You need to be seen first.

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This much has been worked out about one root sitting in the kitchen.

There are compounds, there is a site those compounds bind to, and what that site does is known as well. Dry it and the compounds change, and so it becomes a different medicine.

Being common does not mean it does nothing. The more common a thing is, the better it is to know what it does before using it.

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References

• How ginger compounds inhibit the human 5-HT3 receptor — Neurogastroenterology & Motility, 2013
• A pooled analysis of twelve studies of ginger for nausea and vomiting in pregnancy — Nutrition Journal, 2014
• The process by which gingerol converts to shogaol with drying and heating — Molecules, 2018

Written by Dr. Heo Ji-young (PhD in Korean Medicine Pathology, Kyung Hee University · former Research Professor of Herbology, Kyung Hee University)