Understanding the impacts of sugar on our health is not an easy task. Food science is complicated and imperfect, but some level of confusion has been added in by sugar industry stakeholders, who have spent millions over the past few decades to support studies that would produce desirable results for their industry. That’s why a little historical journey will help us spot conflicts of interest and put current findings in perspective.
WHY SUGAR IS A MODERN PROBLEM
For thousands of years, the human appetite for sweetness could only be satisfied by eating fruit or, when our ancestors got lucky, from the honey produced by wild bees. But around 2,500 years ago, people found that they could produce sugar by extracting and drying the sap of sugar cane.1
Producing and extracting sugar was time-intensive and challenging – this made sugar incredibly expensive. Only the rich could afford it, and still only in small quantities. By the 1850s, the world production of sugar was around 1.5 million tonnes per year, with new methods of sugar extraction and refinement driving prices down. As sugar became increasingly affordable, consumption rose to mind-boggling levels within just a few decades.1
HOW MUCH SUGAR DO WE CONSUME TODAY?
Today, the world production of sugar has climbed to around 180 million tonnes per year. On average, Europeans eat 30kg of added sugar per capita every year – that is a whopping 82g per day.2 As wealthier countries became more health conscious, sugar consumption began declining in the ‘80s, while sugar consumption rose in poorer countries.3, 4
Yet, compared to pre-War times, Western sugar consumption levels still remain high. In Italy, my country of origin, people would eat 9kg of sugar per capita per year before World War II. Today that number has risen to 25kg.2
WHY IS THERE SUGAR IN EVERYTHING?
Many of us will be shocked to read that Europeans eat that much sugar on average. Yes, while European families have been buying less “household” sugar over the years, sugar has been added in a lot of packaged foods for decades. Sugar doesn’t come to us just in the form of sweets such as confectionery, sodas, or biscuits, it hides in savoury foods too: pasta sauces, soups, spreads, stews, even crackers and chips. Today, unless we read otherwise (i.e., “No added sugar”), we can assume that sugar is in the list of ingredients.
And there’s no mystery as to why sugar seems to hide everywhere: it simply is one of food manufacturers’ best friends. It’s not only its sweetness that makes it attractive, but also its cheaply added bulk, its solubility in water, and its ability to inhibit the growth of mould and bacteria. For these and many other qualities, sugar is a versatile ingredient and helps to produce foods that can both last long and taste good. Today, sugar is a booming industry: worth more than 63 billion euros in 2018.1
EARLY SUGAR RESEARCH & THE OBESITY EPIDEMIC
Until only a couple of centuries ago, people in the West were consuming low enough quantities of sugar to be considered irrelevant. So, the effects of sugar on our bodies managed to go unnoticed for a long time – no one thought sugar could be bad for us. But during World War I, questions around the health benefits of sugar began circulating.5
PHYSICIANS SPEAK UP AGAINST SUGAR
Several U.S. physicians signed a letter in 1918 suggesting a reduction of sugar in people’s diets. According to them, sugar was starting to dominate a big chunk of our calories without bringing any other nutritional benefit. It wasn’t until the 1950s and 1960s, when many more U.S. men started to suffer from heart disease and obesity that many began to question how sugar could be intrinsically bad for us.5
THE LINK TO HEART DISEASE: SUGAR VS FAT
What was responsible for the rise in weight and heart disease? Two physiologists had brought forward their own hypotheses: John Yudkin (British) hypothesised that sugar was the culprit of obesity and heart disease; in contrast, Ancel Keys (American) thought excess fat was responsible for the increase in cholesterol, which would cause coronary arteries to harden and narrow and so cause heart disease. Yudkin and Keys were both trying to answer the same question, but they ended up with opposing theories to one another. While Yudkin thought sugar and fat could both be problematic, Keys discredited Yudkin’s theory as “a mountain of nonsense.” Instead of collaborating, the two ensued in a row of personal quarrels.6
THE SUGAR INDUSTRY & SKEWED SCIENCE
This is where the sugar industry enters the story. It’s no surprise that Yudkin’s theory threatened the interests of sugar companies and associations that represented sugar producers, processors, and refiners. To discredit Yudkin’s sugar theory further, the sugar industry used his squabble with Keys: The British Sugar Bureau dismissed Yudkin’s claims about sugar as “emotional assertions,” the World Sugar Research Organisation called his book “science fiction.” As The Guardian puts it, Yudkin wasn’t just silenced – he was buried.6 Simultaneously, in the U.S., the Sugar Research Foundation’s director suggested that the foundation could “embark on a major program to counter negative attitudes toward sugar.”7 This program involved funding studies whose research question had been carefully designed to either drive attention away from sugar, or to assess the data in ways that could allow researchers to conclude that sugar doesn’t cause disease.7 Here are some examples of how the sugar industry attempted to affect research and public opinion of sugar.
“FAT, NOT SUGAR, IS RESPONSIBLE FOR HEART DISEASE”
In 2016, a group of researchers exposed correspondence between the Sugar Research Foundation (SRF) and some Harvard scientists from the 1960s. The correspondence demonstrated that the sugar industry funded research that turned attention away from sugar’s link to heart disease, toward fat and cholesterol as the bigger culprits – funding that amounts to the equivalent of half a million dollars in today’s money.7
Harvard scientists were asked by the SRF to review available evidence that linked nutrients to heart disease. At the time, scientific evidence was still quite weak for both fat and sugar in their link to heart disease. However, when they published their review in the New England Journal of Medicine, the Harvard scientists downplayed the studies that pointed at sugar’s link to heart disease, but did not do so for the studies that researched fat.7,8 On top of this, the scientists didn’t disclose any conflict of interest, as this practice wasn’t compulsory yet. As a result, the Harvard review was accepted uncritically by many.
“SUGAR DOESN’T DAMAGE TEETH”
This is not an isolated case. To distract dental professionals from suggesting limits on sugar to prevent tooth decay, the SRF also lobbied the National Institute of Dental Research to fund studies on causes of tooth decay that focused on the effects of literally anything but sugar: vaccines, fluoride treatments, mouth bacteria, tooth brushing, and any other possible cause. The result? In 1971, among the methods promoted by the National Caries Program to reduce tooth decay, there was no mention of exposure to sugary foods and drinks.9
Attempts to influence dental research are not just something of the past. In a 2019 article published in The Lancet, a group of oral health researchers have complained that the sugar industry is still influencing oral health policies and professional organisations through well-developed corporate strategies.10
“SUGAR DOESN’T MAKE YOU FAT”
Using distorted research for marketing strategies, the Sugar Association managed to claim sugar’s health benefits for decades – at some point, sugar was even positioned as a diet aid to counter obesity. Here are just some advertisements from the 1970s:
The “fat time of day:” you’re really hungry and ready to eat two of everything. Here’s how sugar can help.11
You’ve probably had people tell you they’re avoiding this or that because it has sugar in it. If you want to see how much sense there is to that idea, next time you pass a bunch of kids, take a look. Kids eat and drink more things made with sugar than anybody. But how many fat ones do you see?1
As NYU Professor of Nutrition, Health Studies and Public Health, Marion Nestle (who has nothing to do with the Nestlé food company) put it in her book Unsavoury Truth, the sugar industry has been using the same methods applied by the tobacco industry to influence policy and public opinion for decades. These methods include casting doubt on the science and funding research to produce desired results or shift attention away from studies that condemn the health effects of sugar, but they don’t stop there. The sugar industry has also been using courts to challenge critics and unfavourable regulations.9
Marion Nestle told me that the sugar industry is pursuing similar goals even still today. “The sugar industry’s goal in funding research is still to demonstrate that sugar has no adverse health consequences, that research demonstrating the contrary is so badly done that it should be ignored, and that physical activity is a more important determinant of obesity than diet.”
The issue with industry-funded studies is that they tend to be more biased – intentionally or not. Several studies found that most industry-funded studies favoured sponsors and their products.12, 13 When looking at sugar-sweetened beverages and their health risk, industry-funded studies were eight times more likely to produce favourable conclusions than those funded by non-industry sources.12 Marion Nestle shared with me that “in general, industry-funded studies and opinion pieces tend to support the commercial goals of the funders.” At least scientists are now compelled to disclose conflict of interest and funding sources, so this can help us put their findings in perspective.
SO IS SUGAR REALLY BAD FOR YOU?
Despite what the industry wants us to believe, the short answer is yes: excess sugar is bad for you. The World Health Organisation strongly recommends to reduce intake of free sugars down to less than 10% of total energy intake, and even states that it would be better (if possible) to reduce it to below 5% of our total energy intake.14 The US Dietary Guidelines Advisory Committee gives similar indications, suggesting that in an ideal diet, added sugars would take only 6% or less.15
This means that for the average caloric intake recommended for males (2500 calories per day), sugar should not exceed 60g per day. For women eating a diet including 2000 daily calories, that would be even less – around 50g. That’s quite a lot less than the current European average, which surpasses 80g per day.
SUGARS’ EFFECTS ON OUR BODIES
There are two fundamental reasons behind these recommendations: too much sugar in our diets will at least lead us to develop cavities and to gain weight.14,15 But we have to be careful: although it would be fantastic to have found the cause of weight gain, attributing the responsibility of a complex phenomenon such as obesity to a single nutrient would be a sloppy simplification. The majority of studies have actually shown that if you remove sugar from your diet but substitute the same amount of calories from other sources, your weight won’t change.16 So sugars are not the cause of obesity, but one strong contributing factor.
Some of us might have heard that sugar is linked to many other diseases, such as diabetes and cardiovascular disease, and might be surprised that these links are not included in the reasons behind public health guidelines. However, evidence directly linking sugar consumption to other diseases is low, and that’s why health organisations can’t include those arguments in their rationale until more robust conclusions are reached. Plus, the link between weight gain and many other diseases, such as diabetes, cardiovascular disease, and even cancer, is already well established.17 This means that even if sugar is not directly linked to these diseases, if we overeat sugar and become overweight as a result, we are also going to increase our risk of developing them.
THE POLITICS OF THE SUGAR INDUSTRY
Regardless of the strength of evidence for specific diseases, today many of us believe that a healthy diet should include as little sugar as possible – and the industry knows that.
But in its struggle for a better public image, the industry has proven not to be a cohesive whole. Producers of sweetened foods and of different kinds of sugar have started to battle within the industry over which sugar or product is the worst – and in turn, which one could be advertised as the healthiest.
HIGH-FRUCTOSE CORN SYRUP
The U.S. sucrose industry, for example, has been trying to identify high-fructose corn syrup (HFCS) as the only evil around, and to give you an idea of how far they went: HFCS can’t be legally referred to as “sugar.” If you dare to call it sugar publicly, you could be brought to court.9
Because HFCS was much cheaper than sucrose, food processors put it in every product they could since the 1980s – just as obesity numbers began quickly rising. But as soon as some early (and far from conclusive) research suggested that fructose would be digested in a different, potentially more harmful, way than other sugars in our bodies, the sucrose industry took the opportunity to identify HFCS as the new evil of the sugar world.9
To understand the argument against HFCS, we need to understand its molecular structure. You see, HFCS and sucrose are molecularly very similar: both are made up of glucose, fructose, and water. However, a molecule of sucrose has the same amount of glucose and fructose in it, while a molecule of HFCS carries 5% more fructose than glucose.18
With this in mind, this is how the industry-supported reasoning goes:
- Some studies have concluded that fructose could be more harmful than glucose,
- HFCS includes more fructose compared to sucrose,
- So HFCS must be worse for you than sucrose.
In reality, scientists claim that 5% more fructose doesn’t represent a significant difference between the two types of sugar, and so both HFCS and sucrose would present the same exact risks to the human body. Sucrose, or natural cane sugar, is not “the healthy alternative” to HFCS, contrary to what the industry has been trying to convince us.9, 18
It’s also important to point out that many of the fructose studies administered exceptionally high doses of fructose to participants. So, until we have research with more realistic fructose intakes, we can’t quantify its impact on the human body in a reliable way.18 The take-home message from nutrition scientists is the same here: the problem is not one type of sugar against another, but too much total sugar consumption.
FOR PROFIT OR FOR PEOPLE?
The history of sugar research is not unlike that of many other foods. Conflicts of interest loom in nutrition research, and we need to build an intellectual toolkit to discern honest and unbiased scientific claims from bogus and marketing claims. First of all, we need to remember that science is slow and complex, and we often have to wait for several studies to reach the same conclusions over many years before we can be confident that a conclusion reflects what happens in reality. The problem is that the slowness and complexity of science often can’t compete with the simplicity of marketing concepts, specifically designed to be digestible and easy to spread, regardless of their truth.
Learn more about the history of sugar research in episode 17 of the Food Fight podcast: Is Sugar the New Tobacco?
So when a single food or macronutrient is demonised as the sole responsible for many diseases, or some other food is celebrated as carrying the most wonderful healing properties, let’s be on the lookout for who could benefit if we were to believe that. Let’s inquire for a link to the original source of information, and then check at least the conflict of interest section.
Knowledge is important. Now that most citizens in wealthy countries are aware that eating too much sugar is bad for us, the industry has accepted defeat and moved on to some extent. But in turn they are now marketing most of their sugar-filled products to the poorer countries and minorities in wealthier countries, who don’t always have the resources to make healthier choices. That’s why once we’ve built our own anti-bogus kit, we should share it as widely as possible so that humanity as a whole can benefit from it. Only once we all know about the practices that the food industry uses to skew science and influence our opinion, will our societies be vaccinated against – and therefore immune to – this kind of malpractice.