Diets are like clothing fashion trends: they come into and out of style. And if you wait long enough: back into style again. One of my favourite pop culture research tools is Google trends. Google trends keeps a global finger on the pulse of what’s hot and what’s not in the world of nutrition and diets. And tracks this over time based on the popularity of search terms. Now a research team has mined this wealth of data to produce a snapshot of the ever-changing diet trends with some surprising results.
Keeping up with diet trends can be a full-time job at times. There is never a shortage of new nutrition and diet fads with their promises of easy and sustainable weight loss and a new diet paradigm to a way of eating that will be best for your health. Some of these trends come into and out of popularity. The keto diet is nothing but another ‘rebranding’ of a low-carbohydrate diet that has come into and out of popularity for decades.
Some of the nutrition trends, like the Mediterranean Diet, have a strong research base behind them. Whereas as others are just pure made-up fantasy. I’m talking about you Blood Type Diet.
With an estimated 80 percent of Internet users perceiving Web health-related information as being reliable, and up 85 percent of people using the Internet to search for health and nutrition information, then the Internet has a powerful ability to shape nutrition and diet trends - be it a desire to lose weight or just eat healthier.
Enter the stage for my most popular research tool – that being Google Trends. Google Trends is a freely accessible tool dedicated to estimating the relative search volume of queries done on Google. You’ll find it at trends.google.com Google trends works by giving a search term a relative value of zero to 100 where 100 equals the peak of popularity in a given period and geographic location and zero equals complete disinterest.
Enter a Polish research team who amped up the Google Trends analysis to create a research paper that aimed to rank the most popular diet search terms among Google users globally and locally as well as seasonal trends in the years from 2004 to 2019. I’ll link to the paper in the show notes https://www.sciencedirect.com/science/article/abs/pii/S0899900720300423
The team analysed Google Trends for 47 different search terms covering a whole range of popular diets and ways of eating. Most of them I had heard of, but a few I hadn’t: the cookie diet anyone? Yes, eat your way to thinness by chowing down on cookies. Oh, wait. And also eating a small evening meal and keeping your total energy intake to under 1200 Calories a day which includes the cookies. Which you have to buy of course from the diet promoters. Okay, I’ll stop there before I facepalm myself into unconsciousness. Instead, let’s move on to what the research study found.
Despite the hype you may hear about keto and other flavours of low-carbohydrate diets on social media, it was veganism, vegetarianism and gluten-free that were all ranked well above them and filled the first three search term popularity spots by a substantial amount. Next came a variety of rebrandings of low-carbohydrate diets and then tailing out came all manner of flotsam and jetsam from intermittent fasting and low-FODMAP diets right through to juice fasting and the grapefruit diet.
The analysis of the trends from the most recent years showed an emerging interest in the low-FODMAP diet, intermittent fasting as well as topics related to plant-based diets and pescetarianism. All of this completely gels with my own observations for what the media reports on and people ask me about the most.
Next, the research team looked at the change in popularity over time and this is where the real gold lay in the study as it showed the true fickle nature of many of these trends and which rightly should be called fads. Interest in several topics including the 5:2 fasting diet, The Cambridge diet, Cookie diet, Juice fasting, Master Cleanse, the Paleo diet and raw veganism showed a clear fad pattern.
And in a surprise to no-one, interest in all topics showed seasonal variation with the strength of most search terms peaking in January as New Year’s resolutions kicked in and falling to their lowest number of queries in December representing the full year-long cycle of all diets.
What this study uncovered was the diversity of trends and fads that people are exposed to, by choice, when they go searching on the Internet. So, with so much noise and information covering every possible position on the nutrition spectrum, how is a person to make sense of the conflicting nutrition messages they read and hear about each day?
Carbohydrates cause weight gain. Fat causes weight gain. We are designed to eat like our Palaeolithic ancestors. Glycaemic index is the key to health. Intermittent fasting is the best way to lose weight. Sugar and grains are toxic. Saturated fat is bad for you, no wait, now it’s good for you.
I could not blame anyone for throwing their hands up in despair, proclaiming that all nutrition health messages are bunkum because they are always changing. I am beyond the point of tired in wanting to debate the merits of anyone particular diet over another. Nutrition is not always an exact science and we don’t always have the best quality evidence to support recommendations.
But nutrition scientists and people behind the construction of public health nutrition recommendations are not evil people who seek out to confuse and mislead the public. Such work is done in the context of seeking out all of the available evidence and attempting to see what side of the health ledger the evidence tips. Evidence that does change over time.
But digging deeper, the basic fundamentals have never really changed. Despite a never-ending stream of sensationalist fad diets, there are common themes that overlap across all of the popular diets – themes that give you the keys to long-term health in a simple-to-understand message.
Putting a heavy dose of some much-needed sense into the mostly pointless ‘whose way of eating is best’ argument, a review paper has made a real effort in trying to answer the almost impossible question of what is ‘the’ best diet for health. The authors looked at the defining characteristics and rationale behind all of the ‘diet camps’ that stake their flag in this space. And I’ll link to the paper in the show notes https://www.annualreviews.org/doi/full/10.1146/annurev-publhealth-032013-182351
And here is the key summary of all the analysis. The different diet ideologies could be distilled down into several distinct dietary patterns. And these were, in no particular order: a low-carbohydrate diet, a low-fat diet, a low-glycaemic diet, a Mediterranean diet, a mixed-balanced diet more in line with broad dietary guidelines, a Palaeolithic diet, and finally a vegan or vegetarian diet.
Now firstly, there are distinct differences between each of these dietary patterns, but there is also a lot of overlap, and the overlap is where the key message is. A common theme of all these dietary patterns was the foods that were NOT eaten, and these were mostly highly refined starches, added sugars and ultra-processed foods. And what about the commonality between them of what WAS eaten? There was a strong emphasis on whole plant foods with or without lean meats, fish, poultry or seafood.
To quote from the authors: “The clutter of competing claims likely obscures the established body of knowledge and forestalls progress, much like the proverbial trees and forest.” Translation – there is too much noise about what differentiates the different diet ideologies, when more focus should be what unites them. There is no one best diet for health, but a theme that can be copied and individualised. A dietary pattern that is made up of mostly minimally processed plant foods and which is low in highly processed foods and added sugar consistently comes out on top in offering the best long-term health. There is no one food or food group that deserves demonising. A dietary pattern is a flexible way of eating, not a set of rules that has to be followed to the letter of the law.
Get the basics right and you can hit the snooze button on needing to ever again pay attention to anything you ever read or hear in the media or from populist diet book gurus.
Research Wrap Up
Now on to my research wrap up segment where I profile a study that has grabbed my attention during the week. And for this week, it is a study that looked at diet habits linked to surviving cancer.
Cancer is a major disease killer. Thanks though to earlier detection and improved treatments, more and more people are surviving a cancer diagnosis and going on to live long lives. Well-supported diet and lifestyle recommendations are already in place for how a person can lower their risk of developing cancer. Less evidence exists though to make clear recommendations for diet for cancer survivors.
Looking at studies that surveyed the diet and lifestyle habits of cancer survivors finds a sparse research field. Only a few key cancers have been studied and results can appear contradictory. Further complicating things, some studies only looked at pre-diagnosis diet while others examined post-diagnosis diet.
With the mixed research field of diet among cancer survivors, a German research team collated together 117 studies involving over 200,000 cancer survivors into a single meta-analysis. And I’ll link to the study in the show notes. https://academic.oup.com/nutritionreviews/article/74/12/737/2656957
What they found was perhaps not too surprising. Higher consumption of vegetables and fish had a favourable link with longer survival. Alcohol was linked with a worse outlook. Grouping together whole diets found that one type of diet stood out. Termed wholefoods, prudent or healthy depending on the study, a common theme was a dietary pattern high in fruit and vegetables and wholegrains, but low in red processed meat, refined grains and high-fat foods. Eating around this dietary pattern was linked to a 22 percent lower risk of earlier death.
The opposite of a healthy diet was labelled as a Western diet, high-fat diet or high-sugar snacks diet or simply, an unhealthy diet. Comprised of processed meat, refined grains and lots of added sugar, this diet was linked with a higher mortality risk from cancer of almost 50 percent compared to similar people following a healthier diet.
Greater numbers of people are surviving cancer today than ever before. With more people surviving cancer comes a greater need to spotlight the key lifestyle choices that raise survival odds even more. Dietary patterns that are closely connected to foods near to their natural state such as fruits, vegetables, fish and wholegrains currently sit at the top of evidence recommendation for people with cancer to be steered towards.
So that’s it for today’s show. You can find the show notes either in the app you’re listening to this podcast on if it supports it, or else head over to my webpage www.thinkingnutrition.com.au and click on the podcast section to find this episode to read the show notes.
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I’m Tim Crowe and you’ve been listening to Thinking Nutrition.