Coffee is a drink that punctuates many of our lives. Millions of us depend on this dark liquid to start the morning, or to break up the day.

It has also become quite an expensive habit. But before we baulk at paying £5 for a flat white, it’s worth thinking about the price paid by the coffee farmers who provide its base ingredient.

For behind every latte and espresso lies the toil and stress of coffee farmers, who face serious challenges to bring their popular product to the rest of the world. Harvests can be devastated by extreme weather events or pests and plant diseases, while volatile market prices add another layer of worry, making future income uncertain.

This volatility exists in other crops, but especially so for coffee, the price of which is extremely unpredictable. It can rise and fall frequently because of the weather, market demand and the state of the global economy.

Coffee trees take up to four years to grow and produce beans, and cutting them down is expensive, so farmers can’t easily change how much coffee they produce based on price changes.

But price volatility means that farmers can’t be sure about their income at harvest time, which can be incredibly stressful. And our research shows just how much that unpredictability affects farmers’ mental health.

Our work focused on farmers in Vietnam, a country where coffee production has soared over the last three decades. From accounting for just 1.2% of world output in 1989, Vietnam is currently the second largest producer in the world (after Brazil) producing just under 30 million 60kg bags a year. Vietnam produces mainly “robusta” coffee beans, grown by small farmers in the central highlands region of the country.

Using data from a long-running observational survey to assess mental health, we looked at how Vietnamese coffee farmers experienced symptoms of depression including sadness, hopelessness, lack of concentration and poor sleep – and how these were linked to monthly international robusta coffee prices.

Using a range of techniques to interpret the data, we found clear evidence that being exposed to coffee price fluctuations increased depressive symptoms among farmers of the crop. They also had lower overall wellbeing because of greater mental stress and worry over their economic future – and drank more alcohol.

The impact of all of this uncertainty is significant. According to the World Health Organization, poor mental health is a major contributor to the global burden of disease, especially in low-income countries where mental illness and poverty are closely linked.

Estimates suggest that as much as 80% of the world’s depressive disorder burden is borne by low and middle income countries. But these issues are often overlooked, even though they are crucial to addressing poverty.

What can coffee drinkers do?

There are ways to tackle the mental health effects of coffee price volatility. Initiatives to promote price stability in the global coffee markets and financial literacy among farmers, would be worth pursuing. So too would work to improve mental health support within farming communities, providing resources for coping with stress and building resilience.

Coffee lovers around the world can also play their part by choosing the their drink carefully. Fairtrade certification for example, was set up to help reduce coffee price volatility and the resulting poverty it caused.

It guarantees a minimum price for certified coffee, covering the average cost of sustainable production and reducing the financial risks farmers face. Fairtrade-certified farmers also receive a premium to invest in projects that improve the quality of life for their communities.

And research suggests it is succeeding. A 2005 study of coffee farmers in Nicaragua revealed that Fairtrade farmers are less concerned about the possibility of losing their farm in the coming year compared to conventional farmers. And using data from Costa Rica, research from 2022 has found fair trade certification was effective in increasing farmers’ income.

So the next time you savour your morning cup of coffee, take a moment to consider the people who cultivated the beans which made the drink. Coffee farmers deserve our appreciation – but also our help in establishing fairer, more stable market conditions which safeguard their livelihoods and mental health.