Gut Health Guru Dr Meghan Rossi on how eating little and often can help tackle nausea

Nausea is something we don’t take as seriously as we should. Persistently feeling or being sick can make day-to-day life incredibly challenging and make it difficult to take in adequate nutrition, with effects for the rest of your health.

And both are incredibly common — half of all adults experience nausea at least once a year and a third are actually sick.

It’s common because there are so many triggers, beyond having a stomach bug — including motion sickness, heart problems and anxiety.

It’s also simply a way for the body to rid itself of things it perceives to be harmful, such as too much alcohol or even certain medications.

At the start of my career, I worked on a cancer ward supporting patients undergoing chemotherapy, for whom nausea and vomiting can be one of the most challenging side-effects of their treatment.

I was reminded of this when a reader recently wrote in to say she was trying to manage her chemotherapy-induced sickness by sticking to a bland diet but, understandably, eating this way was starting to ‘pall’ and she was confused about what’s safe for her to eat.

She is certainly not alone and I’ll address her queries about what to eat later — first, let me explain why this side-effect occurs.

The body perceives chemotherapy as a toxin — the nausea and sickness are its way of trying to expel it.

Once it identifies this potential threat, chemical messengers sound the alarm — activating the vagus nerve (which connects the abdomen to the brain), where an area called the dorsal vagal complex triggers the vomit or gag reflex. (Nausea is also part of the body’s way of stopping us from ingesting a potential hazard in the first place.)

But lots of different organs and systems feed into this response, which is why nausea especially is so common. The heart, for example, is also connected to the vagus nerve — so if the heart becomes stressed, as it does when it isn’t receiving enough blood, then messages hit the vagus nerve and can trigger sickness. That’s why nausea can occur with heart disease or during a heart attack.

At the start of my career, I worked on a cancer ward supporting patients undergoing chemotherapy, for whom nausea and vomiting can be one of the most challenging side-effects of their treatment, writes Dr Megan Rossi (pictured)

There are other mechanisms that trigger nausea, too.

Motion sickness, for example, is caused by an imbalance between what we see and the balance mechanism in the ear — the confused messages reaching the brain make it react as if it is being poisoned and so it triggers nausea. (Which is why closing your eyes can help alleviate the sensation, as this stops the mixed messages.)

There’s also an emotional link to nausea — people with anxiety are prone to it — because there are so many nerves in the gut. So anxiety can quite literally give you an ‘upset’ feeling in your stomach.

So what can you do about it?

Did you know? 

Potatoes can count towards your daily fibre intake. As well as eating the fibre-rich skin, allowing a cooked potato to cool changes the structure of the starch in the flesh, turning it from ‘digestible’ starch into ‘resistant’ starch, a type of fibre which feeds the friendly bacteria in your gut. 

For a long time, people thought the BRAT diet (made up of bananas, rice, apple sauce and toast) would help.

The logic behind this was these foods are quite bland and don’t have strong odours that could trigger the nausea reflex, but it has fallen out of favour, not least because it does not provide enough nutrients (there is little muscle-building protein that you need for the immune system or to repair cells, for example).

The most effective way of eating for anyone affected by nausea is to take a little and often approach —eating a little bit of something every two hours.

The rationale behind this approach is two-fold.

First, we know having an empty stomach can make nausea worse as the hunger hormone ghrelin stimulates the production of stomach acid which, if it has no food to mix with, irritates an already sensitive gut, making you feel sick.

Secondly, if you eat the standard three meals a day, this requires your stomach to stretch more, stimulating the already triggered vagus nerve.

Eating small amounts regularly won’t stretch the stomach too much and trigger this reflex.

And when you eat, it’s best to limit foods high in fat (as fat lingers in the stomach, putting more pressure on your stomach walls) or with a strong odour (cold food without a strong scent is best).

Stick to plain food such as dry crackers, and if you can handle something more substantial, a cold frittata (a dish made with baked eggs).

During pregnancy especially (when hormonal changes trigger sickness) studies have found protein-based foods combat nausea better than carbs alone — so, for example, eat eggs on toast or tuna on dry crackers. Protein is thought to calm stomach spasms that exacerbate nausea.

Stick to plain food such as dry crackers, and if you can handle something more substantial, a cold frittata (a dish made with baked eggs). [File image] 

If you have severe morning sickness (i.e. hyperemesis gravidarum) then according to a study in the journal Scientific Reports in 2020, crunchy, sweet uncooked food is best — such as apple or watermelon. Ginger has traditionally been used to combat nausea in pregnancy — and there is scientific evidence to support this.

One review, published in the Nutrition Journal in 2014, including 12 studies in pregnant women, concluded that ginger significantly improved symptoms of nausea compared to a placebo.

Ginger uniquely contains compounds called gingerols, which are thought to speed up gut emptying so food doesn’t sit there too long and ‘trigger’ the vagus nerve.

You can make a tea with an inch of fresh ginger — but be aware it can interact with blood-thinning medication such as warfarin, and if you have a high-risk pregnancy be sure not to overdo it either.

The evidence for ginger in combating chemotherapy-related nausea is less convincing — but another strategy that works is breathing exercises. A trial in Turkey offered 60 breast cancer patients who were undergoing chemotherapy either standard care or breathing exercises for six days — those doing breathing exercises had notably less nausea and vomiting, reported the journal Complementary Therapies and Clinical Practice in 2020.

This was a small study, but diaphragmatic belly breathing has been shown time and time again to calm the vagus nerve, which explains this study’s findings.

And now a word to my reader who asked about what to eat while undergoing chemotherapy.

The treatment can cause low-grade inflammation in the gut —making it more permeable and therefore easier for ‘bad’ bacteria and other infection-causing ‘baddies’ to break through.

This is one of the reasons, alongside the treatment reducing your infection-fighting white blood cells, why you have to be a bit more careful with what you eat. Now is not the time for unpasteurised milk products or fermented foods such as kimchi.

You say specifically that you are craving beetroot and ham sandwiches. The good news is that vacuum-packed meat such as ham should be safe to eat and the same goes for vacuum-packed or pickled beetroot.

So my advice is to have the sandwich and savour every crumb! For a more comprehensive resource on foods safe to eat search: BDA neutropenic diets guidance.