The festive period is often peak potato time. According to YouGov research from 2019, roast potatoes are one of two constants for pretty much everyone’s Christmas dinner (the other being of course, gravy). Kantar’s Worldpanel Division Data from 2021 reveals just how many more potatoes we buy in the week leading up to Christmas than any other time throughout the year.

So what better time to dig into historical food and drink purchases to learn how diets have changed? Using DEFRA’s Family food statistics, and the humble potato as our lens, we can track the UK’s food and drink purchases all the way back to the 1940s – when Britain’s food supply was controlled by rations. It is striking that, although we still love a Christmas spud, British people’s enthusiasm for potatoes has radically changed over the years.

Much of Nesta’s work involves looking for the patterns in our interactions with food – what we eat and where we buy it from – so we can better explain how our food environment affects our health. By that, we mean how the food that is affordable, available and accessible shapes the dietary choices we are able to make.

Looking back at UK food purchasing might tell us something about how our diets have evolved and where we can make changes for a healthier future.

Here are six potato data highlights that stand out.

In 1974, British households were buying almost 1.5 kilograms of fresh spuds a week but by 2022 that was down to around 320 grams.

By 2022, households were buying around 250 grams of processed potatoes a week, up from around 120 grams a week in the late 1970s – around an 100% increase.

Combined with the slump in fresh potato purchases, we can see that the ratio of processed to fresh potato purchases has changed radically in just under 50 years.

Today, the ratio of processed to fresh potato consumption stands at around 0.7 – meaning the average person in the UK purchases 70% as much processed potato as they do fresh potatoes.

In one decade alone – the 1990s – people jumped from eating 20% as much processed potato as they do fresh potato to 40%. Despite the continuing decline in fresh potato purchases, the buying trend for processed potatoes has remained resilient since the 1990s.

Before hitting a peak in 2019-20, processed purchases gradually and consistently increased, as fresh potato purchases fell.

But during the second year of the pandemic fresh potatoes suddenly spiked. Why?

Did people have more time on their hands and so made more food from scratch? The purchase of other fresh vegetables also spiked during this year (clearly visible in our third chart), so maybe.

When we re-emerged after the pandemic, the trend of prior years seemed to return. While both fresh and processed potato purchases fell, processed potatoes made up a greater share of potatoes purchased – and in 2021 we purchased three quarters as much processed potatoes as fresh.

A noticeable dip happened in 1976 – this time in overall potato purchases. 1976 was the year of the sterling crisis, and was also a year that had a prolonged drought and subsequent heat wave. These events seemed to impact both availability and consumption, further demonstrating how external factors in the food environment impact our eating habits.

While some shifts, like the pandemic, can occur suddenly, most changes happen gradually, ultimately transforming consumption habits over years.

When digging into the processed potato numbers it was undisputedly clear just how much we love chips. And we are pretty fond of crisps too.

Today, chips account for 49% of the purchases of processed potatoes, rising to 77% if crisps are included. Despite our diets diversifying, our consumption of chips and crisps has remained steady over the past 15 years – combined, these total over 180 grams a week.

In the mid to late 70s, we met our cravings with a trip to the chip shop (considered a household purchase if taken home to eat). But as more and more families were able to buy fridges and freezers in the 70s, the popularity of convenience food rose, thus securing the top spot for the childhood staple for many of us – frozen chips.

So whilst British diets diversified in the late 1990s, with the rise of pasta and rice perhaps explaining some of the decline of the potato, this doesn’t seem to have affected demand for chips.

The purchase of processed potatoes (including chips) overtook the purchase of fresh green vegetables in the early 1990s.

Though other carbs like pasta and rice have become household staples too, potatoes – despite their decline – are still the top choice for British households. According to YouGov they’re still the most popular vegetable amongst all age groups.

One strength of data visualisation, particularly in data journalism, is its capacity to narrate a story by simplifying complex data into easily understandable information. However, oversimplification can cloud the actual complexities.

There are a few factors that could complicate a straightforward interpretation of this particular dataset. Data collection has evolved in some key ways over its lifetime. For instance, it was only in 1992 that the survey incorporated information about confectionery, alcoholic beverages, and soft drinks brought home. When a visualisation might show shifts that look like big changes, it can often be down to methodological changes rather than changes in behaviour.

It is a widely recognised characteristic of self-reported diary surveys that respondents tend to under report their purchases. But we'll not worry too much about these issues for now (it's Christmas after all).

Some things jumped out– the changing ratio, the green veg, the spike in the pandemic. Do they point to anything? It feels like the shifting ratio of processed to fresh is telling us something – particularly as the ratio seemed to improve when we had more time on our hands.

Taking this longer look back highlights that fluctuations in the food environment can lead to notable shifts in our consumption patterns, reflecting the interconnectedness between broader events and what ends up on our plates. We make choices about food but many are not conscious. Our choices are often instinctive responses to our environment – how food is marketed, what food is available and how convenient it is all influence our choices.

From an early exploration of the wider dataset, it’s clear that the huge shift to the food environment caused by the pandemic affected people’s eating habits. Whether they ‘return to normal’ or have permanently changed is too early to tell. But while we can’t draw definite conclusions, tracking changes in nationally-representative surveys from year to year is a good first step.