If tobacco traveled from America to Europe, sugarcane went in the opposite direction: originally from Southeast Asia, it was taken to North Africa by the Muslims, from there it went to Spain and finally arrived in America, apparently brought by Christopher Columbus himself. On this continent, nourished by the tropical climate and slave labor, it became one of the most important crops in the world. Although for us today sugar is a granulate that we add to food to sweeten it, it is actually a group of sweet-tasting substances that includes, for example, lactose from milk, fructose, and glucose, which is the main food for cells. Our ancestors obtained sugar from fruits, honey and dairy products, which were hardly ever widely available. Millions of years of evolution turned us into animals that know how to find sugar in food. Not only did we develop sugar sensors on our tongue, but sweet tastes are very attractive to our brains: evolution made us avidly seek out certain substances such as sugars, fats or salt, which are necessary and scarce in nature. What represented a clear evolutionary advantage in an environment where food was rarely sufficient became a curse when we were able to increase production to such an extent that today they are omnipresent. Not only do we get sugar from sugarcane or sugar beets, but we also get it, in the form of fructose, from corn. And because it is so desirable and abundant, many processed foods have excessive amounts of sugar (as well as fat and salt) as a way of making them more attractive to us, the consumers. Juices, soft drinks, baked goods and even hamburgers contain huge amounts of added sugar that is often quite hidden.¹See Popkin, B. M. and Hawkes, C. (2016). Sweetening of the global diet, particularly beverages: patterns, trends, and policy responses, The Lancet Diabetes & Endocrinology, 4(2): 174-186. It can appear as sucrose, cane sugar, high fructose corn syrup (this is what the acronym HFCS refers to, which we find on the labels of many products) and other variants. 

So far, nothing would seem to be a problem, except that, in recent decades, we have witnessed an epidemic of obesity in the world that causes cardiovascular problems and very serious chronic diseases, such as diabetes. Today, there are more obese than malnourished people in the world. Moreover, they are more likely to die from overeating than from starvation. Diabetes and cardiovascular problems, along with various types of cancer and chronic respiratory diseases, are the non-communicable diseases that rank among the leading causes of death. 

 Seeing the rate at which obesity was increasing in the world, the immediate question was, "What is causing this?" The first intuition led to the thought that we might be eating too many calories and/or not consuming enough. Then, fats, such as cholesterol, were singled out as the main culprits for a few decades, particularly during the 1970s, 1980s and 1990s. However, after analyzing and reanalyzing the evidence, although a low-fat diet does lower blood cholesterol, there appears to be no difference in the survival of people who have high or low cholesterol levels.²See Ramsden, C. E. et al. (2016). Re-evaluation of the traditional diet-heart hypothesis: analysis of recovered data from Minnesota Coronary Experiment (1968-1973), BMJ.

Instead, the main enemy –not the only one, but one of the most relevant-- would seem to be the amount of sugar we eat in its various and ubiquitous forms, as it was found to be strongly linked to obesity and metabolic diseases. In 2012, an estimated 1.5 million deaths globally were due to diabetes directly, not counting indirect deaths due to cardiovascular and other problems. This is very worrying because, in addition, we are seeing an alarming increase in obesity in children and young people. What will happen to them over the years? 

The World Health Organization has been warning for years about the excess of sugars in our diets: "There is growing concern that the intake of free sugars --especially in the form of sugar-sweetened beverages– increases overall caloric intake and may reduce the intake of foods containing more nutritionally adequate calories, as this leads to an unhealthy diet, weight gain and increased risk of non-communicable diseases".³World Health Organization (2015). Guideline: sugars intake for adults and children.

A meta-analysis⁴A meta-analysis is an analysis of previously done analyses, an analysis of already existing information that is considered a type of evidence of very high reliability. We discuss them in Chapter 3. based on randomized controlled trials shows that decreasing sugar consumption decreases body weight. There is also evidence linking sugar consumption to diabetes. In a large and very recent observational cohort study, a high-sugar diet was seen to be associated with higher mortality, and a high-fat diet was associated with lower mortality and was not associated with cardiovascular disease or myocardial infarction.⁵See Dehghan, M. et al. (2017). Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study, The Lancet, 390(10107): 2050-2062. On this basis, the authors of the study suggest that the recommendations for a healthy diet should be adjusted to take this information into account. 

One of the major sources of sugars in the diet are sweetened beverages such as soft drinks, processed juices or flavored waters (yes, even that innocent looking "healthy" bottle of flavored water has a huge amount of added sugar). Per capita consumption of soft drinks varies widely from country to country, and is particularly high in Latin America.⁶See Singh, G. M. et al. (2015). Global, regional, and national consumption of sugar-sweetened beverages, fruit juices, and milk: a systematic assessment of beverage intake in 187 countries, PLOS One. Depending on the year, the five countries with the highest per capita consumption of soft drinks in the world consume 130-150 liters of soft drinks per person per year, on average. And if instead of looking at the picture we look at the movie, it is worse: these values are gradually increasing, and especially attack the lower income sectors. 

To recapture the practical and applied spirit of this book, we can use the Pocket Survival Guide we presented earlier about tobacco and review each of those questions in light of the particular subject of sugar, with one clarification: we will focus on sugar and not talk about fats or other possible factors. Nothing we say about sugar will refer to anything about issues other than sugar. 

The first questions in the Pocket Survival Guide were, "What is known about the subject and with what degree of confidence? Is there scientific consensus?" 

When we look at the evidence, there are both observations and experiments that connect excessive consumption of sugars (especially those artificially added to foods and beverages) with obesity and with cardiovascular disease and diabetes. Moreover, there is convergence among the available evidence. The causal relationship is clear, but not how much influence this has in practical terms. Regarding the consensus, there seems to be no controversy. 

Unlike what we saw with tobacco and cancer, here it is even more complex to find a single causality, since both obesity and metabolic diseases are multifactorial: even if the influence of sugar is enormous, there are other dietary and behavioral factors, such as a sedentary lifestyle, which are also very important. With such complex issues, it is not only difficult to establish causality, but even if causality has been established, it is difficult to know how much influence each factor has. In fact, none of this exonerates fats, which, apparently, are also harmful in excess. The reality is that today we do not yet know the relative risk posed by excessive consumption of these two sources of calories, but both seem to contribute to these chronic diseases. The main risk factor for cardiovascular disease and type 2 diabetes is metabolic syndrome, a very common condition, especially in developed countries, which is caused by excessive consumption of calories, sugar, fat and salt, together with low physical activity. 

Then, we had this, "Could there be unintentional post-truth factors at work, such as beliefs, emotions, biases, tribalism, confusion about who the experts are, and/or information adulteration?" Possibly. Sugar is very attractive to us, and that may make it harder for us to take into account the evidence of the health damage caused by its excessive consumption. Also, at the level of cognitive biases, sugar is necessary as an energy source, but the problem lies in incorporating more than we need. This subtlety is not easy to translate into concrete actions. As for the adulteration of information, let's analyze this a little more. 

Here's what we know: similar to what happened with Big Tobacco, historical documents from the sugar industry, or Big Sugar, were analyzed. If the tobacco documents were informally called the Tobacco Papers, in a stretch of the imagination, those of the sugar industry are known as the Sugar Papers. A series of internal documents show that Big Sugar influenced sugar-related science and public nutrition policy in the United States for at least the last half century.⁷See Kearns, C. E., Schmidt, L. A., & Glantz, S. A. (2016). Sugar industry and coronary heart disease research: a historical analysis of internal industry documents, JAMA Internal Medicine, 176(110): 1680-1685. When, in the 1950s, a large increase in coronary heart disease was noted, sugar became a suspect. The Sugar Research Foundation, a research arm of the sugar industry, published reviews of scientific papers in the 1960s and 1970s that raised doubts about the influence of excessive sugar consumption on health and redirected suspicion to saturated fats and cholesterol. 

And this brings us to the following questions from the Pocket Survival Guide: "Can there be conflict of interest in the generation of knowledge and its communication? Who funded the research? Who funds the spread of the information? If there is publicity, who is in charge of it?". 

The sugar industry published these papers claiming that sugars were not harmful without clarifying whether or not they had a conflict of interest. Actually, at that time it was not so common to clarify this, but, "curiously", what their publications showed was exactly what the industry wanted to demonstrate. Apparently, they did not lie in those papers, but they did select for reviews what was favorable to their position and ignored what was unfavorable. This worked for two things: on the one hand, the suspect was an "other"; on the other hand, the sugar industry soon realized that if they could establish the idea that people should reduce calories from fat in their diets, that would result in those calories being "replaced" by increased consumption of sugars. 

The issue of conflict of interest is a delicate one. In some cases, research funding comes from industries that have enormous conflicts of interest based on the need for their results to favor them. It was investigated whether, beyond the subject studied, the source of funding could affect the results of a research study and, although causality cannot be established, there is a striking correlation. In the case of the study of new drugs, it was found that 16% of the trials financed by non-profit organizations recommended them as a treatment. In the case of trials that did not indicate who funded them, the figure was 30%, and in trials funded by both non-profit and for-profit organizations, 35%. Finally, 51% of the trials funded by for-profit organizations recommend the drugs studied as treatment.⁸See Als-Nielsen, B. et al. (2003). Association of funding and conclusions in randomized drug trials: a reflection of treatment effect or adverse events?, JAMA, 290(7): 921-928. That this is the case does not necessarily imply that there was any fraud. This could have been caused by minor actions, such as interpreting results in a biased way or highlighting those results that agree with the agenda of the funding industry. When one is assessing the reliability of a claim, whether from scientific fields or not, it is worth looking carefully to see if there might not be some conflict of interest behind it. The fact that an industry funds studies does not discredit them, far from it, but it should be public information so that the rest of us can take it into account. In fact, there have been some very good studies funded indirectly by Big Tobacco, such as the one that allowed Stanley Prusiner to discover a new type of infectious agent that has no genes and that he called prions, a discovery for which he received a Nobel Prize. 

As to the question of whether there are independent associations or expert organizations that systematically review information to seek consensus, in the case of sugar, the closest we have to this are the World Health Organization and the different medical societies of the countries, which generally agree that sugar consumption should be moderated and health policies should be defined accordingly. 

Let's look, then, at the core questions of intentional post-truth: "Could doubt be creeping in where there seems to be certainty? Could certainty be creeping in where there seems to be doubt? Are we being distracted from the core issue by secondary issues? How do political-economic interests fit into all this?" 

When we review the above, it would seem so. Again, we see the post-truth mechanism repeated: generating doubts, creating "alternative facts", moving suspicion elsewhere. 

Does this ring any bells? 

In the 1960s, there were scientists who argued that the main culprit in cardiovascular disease was added sugars. However, by the 1980s, most scientists –whose advice helped shape U.S. nutrition guidelines-- attributed that disease to saturated fats and cholesterol: USDA suggestions, based on industry-driven recommendations, said that "contrary to popular belief, excess sugar does not appear to cause diabetes". For several decades, it was recommended to reduce fat intake, which led many people to switch to low-fat, but high-sugar foods. Today, this is believed to have accelerated the obesity epidemic we are seeing. 

It is confirmed, then, that the sugar industry manipulated the research on the health risks involved. 

They also lobbied and recruited officials, journalists and health professionals who propagated this message. Big Sugar and, in particular, Big Soda were apparently using the "post-truth manual" developed by Big Tobacco. 

How much all this affected the course that would have been followed in relation to health policies, we do not know. By creating doubt, they may have succeeded in postponing for decades public health decisions that could have been taken earlier. All this was accompanied, of course, by very aggressive advertising of sugar products, along with adjectives such as healthy, nutritious or energizing. We may not yet know how important sugars are in these health problems, but the industry's manipulations are real. We have an answer to the question we had raised about whether there might be a distortion between what is actually known and what we know. 

This is not just a thing of the past. Apparently, it is an ongoing practice: Coca-Cola, for example, recently funded programs that promote exercise as a way to combat obesity.⁹ More on this at: https://well.blogs.nytimes.com/2015/08/09/coca-cola-funds-scientists-who-shift-blame-for-obesity-away-from-bad-diets/ Again, the strategy of distraction. 

With this in mind, research on human health coming from groups with potential conflicts of interest should at least be taken with a pinch of salt. Some even argue that they should not be taken into account at all, especially if we consider that public health policies and dietary recommendations are defined on their basis. While publicly funded research indicates that sugars such as sucrose contribute to metabolic diseases, research funded directly by the sugar industry –or by scientists who are connected in some way to that industry-- not only fails to do so, but emphasizes minority evidence and interpretations that benefit the industry, and thus generates the sensation of a real scientific controversy where there is none. Sound familiar? 

We are left with two questions from the Survival Guide. First, "Who benefits from delaying certain actions? Who benefits from defining certain actions?". The damage to health caused by excessive consumption of sugars is a problem that must be addressed. Any decision taken by the States to control or reduce its consumption by the population, such as taxes or regulation of advertising, to give two examples, would be detrimental to the industry and to those who depend on it. 

We will return to this aspect later. For now, let's turn to the last point in the Survival Guide: "Could our beliefs, emotions, biases, tribalism or information selection be influencing the answers to the above questions?" 

Not everyone agrees that there was a conspiracy by the sugar industry to generate the idea of low-fat diets: according to research published in the journal Science, the sugar industry did not come up with this Machiavellian plan, but rather the idea of low-fat diets as a way to combat obesity and cardiovascular problems was already out there at the time, mainly because of some observations that people with high blood cholesterol levels tended to have these health problems.¹⁰See Merritt Johns, D. and Oppenheimer, G. M. (2018). Was there ever really a sugar conspiracy?, Science, 359(6377): 747-750. Likewise, the authors of this work clarify: “We do not claim the sugar industry had no influence on nutrition work at Harvard, nor on the field in general. But we believe that there is no good reason to conclude that Sugar Research Foundation’s sponsorship of a literature review meaningfully shaped the course of dietary science and policy.”

At this point, many of us would already want to get to the concrete part of "so, who do I believe?". "Can you please tell me what I should and shouldn’t eat and be done with it?". We want the solution (and, in fact, it would be great if we had it), not a long narrative of the path that led to it. We want simple, definitive answers. But asking them for simple, definitive answers to complex problems is also a path that can lead to post-truth. 

Of course, we should not demonize without solid evidence. What we saw with tobacco and sugar should not lead us to believe that all major industries manipulate information, nor that we should dismiss a priori any research funded by an industry. What we should do is look for evidence of manipulation and, if it emerges, then we should act. Let us not invoke evidence of manipulation that we do not find, because we may fall into another post-truth situation: being so suspicious of everything that we cannot place trust on anything. 

With sugar, there is evidence of manipulation, but we are not clear how much this may have influenced the definition of public policies. The influence of the tobacco industry is much better documented and the consensus about what happened is much greater than with sugar. Also, it is more distant in time. These discussions about sugar are happening now, and it may take time to see things more clearly and completely, and quite a bit more time for the dietary recommendations to be updated. Our priority at this point is to shorten the time between knowing something with a high level of certainty in a laboratory setting, and implementing public policies based on that knowledge that have a positive impact on people's lives. 

With this in mind, let's move on to a different situation: anthropogenic climate change. Here, things get even more complex.