25/10/2011 1:11:00 PM by by Harold Frazier – Jr. Onion Breeder
Have you ever stopped to wonder what is a sincerely concerned person supposed to do with the information contained in the nutritional panel on a box of food? Ideally, I suppose, they would get exactly 100% of each listed nutrient each day (the RDA), adjusted for their age, gender, body-type and activity level. Unfortunately, this is an impossible task. As a result, the chief outcome of reading nutritional panels seems to be to make the consumer feel badly about their dietary choices. But worse than that, I would argue that an RDA is a ridiculous premise on which to base nutritional choices to begin with, because there is not a single nutrient that needs to be ingested every day for good health. I must admit, however, that the RDA does make for some amusing advertising when exploited by food companies. I personally break up laughing every time I see the advertisement on TV that proclaims that one bowl of cereal contains “half of a day’s fiber”. What, I often wonder, are the symptoms of fiber deficiency, and how will I suffer after I skip lunch? Will I stop functioning, like an automobile out of gas?
The truth is that most Americans will look at a nutritional panel and conclude that a food that contains more vitamins/minerals/fiber and less fat/cholesterol/sodium must be “good” for you. In addition, they will conclude, that because you need to meet your RDA for these items, you had better eat a lot of this food. Foods high in fat/cholesterol/sodium can be justified by the consumer, however, if they have enough “good stuff” in them. This obsession with the content of the food over the substance may slightly decrease the prevalence of vitamin deficiencies by ensuring the public is saturated at all times, but has the unintended consequence of encouraging overeating. Food companies take advantage of this phenomenon by fortifying foods. By adding pennies worth of vitamins, they can convince a consumer with many choices that theirs is a healthy option. If the product also tastes like concentrated sugar, fat and salt, so much the better.
The RDA primarily presents a problem in the translation of scientific knowledge for public consumption. But there are also issues surrounding the source of knowledge. While there seems to have been an uninterrupted flow in scientific progress over the last several hundred years, there are important differences between the work of the early nutritional scientist-physicians and the nutrition science of today. One difference is that the diseases that are sought to be controlled or cured by nutrition are not nutritional deficiencies; the second is that clinical trials are not performed. Scurvy, rickets, and pellagra are all odd diseases, the product of the quirks of a particular time and place. Scurvy only existed when sailors went on long voyages without access to fresh food. Rickets was a problem when children spent all day inside in the dark North. Pellagra was the result of people who ate a food crop without processing it in the way traditional knowledge dictated. Today we face an equally peculiar nutritional challenge: the combination of caloric plenty and a sedentary lifestyle. This combination is clearly the cause of the obesity problem in developed countries (genetic contributions aside), and thought to be a powerful contributor to heart disease and diabetes, two of the most common causes of mortality. To make this point explicit: America’s current nutritional problem is one of excess, not deficiency. To illustrate this point, consider another peculiar ‘disease’ of the modern day, hyperbrominemia. This is a rare skin disorder that can be caused by consumption of more than a liter per day of soda that contains brominated fats as a stabilizer. If hyperbrominemia were a major health epidemic, the solution would be clear; don’t drink so much of that soda. The solution to obesity is equally clear; eat fewer calories. Yet it seems that people are always looking looking for what they should eat to lose weight and prevent heart disease. This makes very little sense.
The truth is that one can lose weight by eating less of anything, and by eating more than you want of most things. Consider the biological facts: It is very difficult to maintain body weight by eating only vegetables or fruits, with the exception of particularly starchy (potatoes) or oily (coconut) items. The following amounts would be required to supply 2000 calories: 8.5 pounds apples; 25 pounds of tomatoes; 3.75 pounds beans. Humans also cannot maintain weight on a diet of lean meat alone, due to a phenomenon known as ‘rabbit starvation’ (also known as the ‘atkins diet’), but would require 2.75 pounds of lean cooked meat to supply the daily calories if we could. It isn’t even that easy to eat 2000 calories of starchy foods. You would need to eat 4 cups of wheat flour, the equivalent of 2 standard loaves of bread, or a 5 pounds of cooked potatoes. The culprits in the obesity epidemic are the only nutrients that I have not yet mentioned: refined carbohydrates and fats. Less than three cups of sugar contains 2000 calories, and the same is true of about a cup of oil (~8oz). It should be noted that it is very hard to survive without these obesity-inducing chemicals. If you doubt the importance of these nutrients in the human diet, perform an experiment on yourself: eat for a week without any fats or refined carbohydrates. You will need to eat a much larger volume of food, eat more often, and will probably lose weight.
As a species, humans have specialized in the acquisition of calorie-dense foods through the development of pastoral and agricultural ways of life, and obtained a higher extraction of calories from these foods by the development of cooking. After an abundant source of calories was domesticated, we purified the products through refinement, crystallization or rendering. These processes removed vitamins but made the calories more concentrated and/or easier to preserve. The whole goal was to make calories more readily available over the whole year, which was a logical development in a world where finding enough calories was a daily challenge. In our peculiar modern situation, these calorie-dense foods are the source of what is commonly referred to as ‘bad’ foodstuffs, ‘empty’ calories, and the like. They are a major ingredient in snack food, and smaller quantities are found in most pre-packaged or pre-prepared food. They are what make many of these overcooked and stabilized foods taste good. Ironically, the development of fortified foods enabled their further use and consumption in a way, by adding vitamins back to a concentrated form of calories and protein. If you have the time, you might consider comparing the contents of a box of fortified breakfast cereal with a sack of complete broiler chicken feed, something scientifically designed to increase the weight of the bird a quick and efficient way.
Most ‘whole’ or minimally processed foods, on the other hand, have so much undigestible material and water associated with them that it is difficult to eat enough to become obese from eating them. These things make up the majority of what people call ‘good’ foods, especially the fruits and vegetables. With regards to the obesity epidemic, what makes these foods good is what they lack: concentrated calories. There is a reason that most people don’t consume as much of these foods as is recommended by the USDA. For one, they often require cooking to be palatable, which takes up time. Two, they often don’t have the same physiolocial or gustatory effect of food loaded with fat and sugar. Instead, people learn from advertising and nutritional information that what they need from ‘good’ food is not the food itself, but the ‘good’ components. The unfortunate result is that people believe that they can offset the consumption of ‘bad’ food by eating more of the ‘good’ food. In fact, the two are not in opposition. The ‘bad’ food causes a problem when in excess, while the ‘good’ food causes a problem when in deficiency. It may seem obvious when it is written down, but make a point of observing food choices among your acquaintances, and you will see how pervasive this logic is among Americans.
The root of the information that is disseminated by the food companies, USDA and the media comes from biological scientific studies. By and large, this work is designed to address a very specific question in a very limited context. Each nugget of information is added to the scientific record by publication of the results in a scientific journal. The idea is that these nuggets will eventually add up to a greater understanding of a particular topic. The scientific world has its own set of politics. Scientists must obtain funding, and to do so they must generate scientific publications. These publications must have high status, so often the scientists are forced to make the results of their work seem more relevant and applicable to humans than it actually may be. These extrapolations are primarily found at the end of an introduction and the end of the discussion section in a scientific paper. They are meant to generate interest to promote ideas and careers, and have no scientific meaning. When media sources pick up on science as either a press release or via actually reading a scientific publication, what they pass on are these extrapolations. The actual nuances of methods are far too dry to bother with, and the caveats implicit in the methods and results take away from the sense of wonder and progress. Extrapolation is the majority of the ‘newsworthy’ part of science. This is not to say that scientists are looking to deceive. Within the context of the experiments, the results of the experiments are relevant. However, the translation through the media and advertising results in people doing things that are not sane, like making sure that they drink one and a half glasses of red wine every day.
Nutritional biomedical scientists come in two basic flavors: experimentalists and epidemiologists. These two groups attack the questions in very different ways. Experimentalists directly alter the genes, environment or diet of a few creatures in a controlled way, and measure the outcome. The results of these experiments are generally straightforward: an experiment is performed and the effect was recorded. Before drawing wider conclusions, however, critical questions should be asked. These questions include whether the appropriate controls were performed, whether the treatment was realistic, the model relevant, and whether the outcomes measured were informative. For example, if rats had been used to test the activity of vitamin C in preventing scurvy, the results would have been negative, because rats can make their own vitamin C. So the rat is a bad model for scurvy. The reader should be aware of this however, because an appropriate control for this experiment would be a placebo, with a scurvy outcome. The previous example was a straw man, and would never actually be published, but the scientific literature abounds with questionable model systems and poorly controlled experiments. For example, there was a paper published that is commonly cited by genetically modified food critics that shows changes in intestinal growth in rodents fed a GM-potato diet (Lancet. Volume 354, Number 9187 16 October 1999). The rats were fed a potato that produced a transgenic carbohydrate binding protein called a ‘lectin’. One control was performed, feeding the animals a non-GM potato with lectin added to the diet. Most of observed changes in intestinal growth were due to the presence of the lectin, but not all of them. The extrapolation was made by the authors that the changes in intestinal growth not explained by the lectin were due to the genetic modifcation process itself. But we cannot know this, because the appropriate control was not performed; feeding the rats a transgenic potato with a different gene, perhaps a potato gene. We could also ask what these changes in intestinal growth mean for the long-term health of the rodent. Unfortunately, the only part of this study that is widely transmitted to the public is that GM-potatos cause abnormal intestinal growth.
One can also question the relevance of the animal models employed in these studies. Many diseases (cancer, diabetes) are induced in laboratory animals in an expeditious fashion either with genetic mutations or toxins, and there is no reason to presume that these means of reaching a clinically similar state accurately reflect the normal progression of a complex long-term disease. Sometimes these means are used because the lab animal in question never naturally gets the disease in question. This should set off alarm bells in any rational person. To be clear, there is no reason to presume that rodent models will indicate human results, other than the presumed similarity due to our common ancestry. All one needs to do is peruse the widely available toxicity data from the National Institute of Occupational Health and Safety (NIOSH) to see that all mammals do not respond in the same way to various (in this case toxic) treatments. Depending on the organism, the lethal dose of a given toxin can vary by more than 10-fold. Why should we believe that nutritional effects on cancer or diabetes are any different?
The obvious answer the problem of relevance is laboratory studies to use the rodent models to perform preliminary experiments, then conduct studies on humans before drawing final conclusions and making recommendations. Unfortunately for science and rodents, and fortunately for humans, we cannot experiment on humans the way we do with lab animals. Even if we could perform a clinical trial on the impact of this or that nutrient on the incidence of cancer or diabetes, the years or decades that are required for these diseases develop in humans would make such experiments nearly impossible. The closest we can get to this ideal are a few people who are so obsessed with science or immortality as to take the results of laboratory studies and mimic them in their own lives. For example, there is a cadre of people who have placed themselves on a calorie restricted diet, eating 800-1200 calories a day. They know that laboratory experiments have shown that a wide variety of creatures will have a statistically increased lifespan by eating a near-starvation diet. Here again, however, we have the question of whether the laboratory results are relevant in the real world. Do oldster rats in a sterile cage ever get influenza, for example? What will happen to a 80 year old person with no body reserves when they get sick, even if they have the heart of a 40 year old?
The other class of scientists that study human nutrition are epidemiologists. Epidemiologists monitor hundreds to millions of humans, either over time or as a snapshot from public health data, and use statistics to determine relationships between lifestyle factors and health. There are a few that perform limited interventions in human diet on a moderate scale. Epidemiology is powerful, but has a terrible flaw; the results are always correlative, not causal. The way studies are performed in epidemiology are much more limited than in laboratory science. In a lab a scientist can test the same hypothesis in many different ways through intervention; they can increase or decrease dosage in a controlled manner, reverse the order of treatments, try alternatives. This level of rigor eventually allows a certain amount of confidence that, within the defined context of the experiments, that a given treatment actually caused an outcome. Not so with epidemiology. All the epidemiologist can do is ask questions. For example: Did you shower today? Are you homeless? An epidemiologist might conclude from this data set that people who don’t shower are more likely to be homeless. Does this mean that not showering causes homelessness? Maybe in a few individuals, but in most cases homeless people just don’t have access to showers, and are homeless for some other reason. Apply the same argument to common epidemiological adage that “Red wine is good for you in moderation”. Does red wine make you more healthy? Or are people with low levels of stress more likely to drink, and the low stress makes them healthy? Or maybe they are Italian, and Italians are healthy? A good epidemiologist tries to control their data set for these kinds of confounding variables; but cannot control them all because people do not exist in a laboratory environment. Even if they did, the results would probably not be the same as in the real world.
When we add these two systems of biomedical research together in light of the current disease challenges, we get our answer as to how the ever-expanding (and changing) body of nutritional mandates has developed. Typically, it might go something like this: an epidemiologist notes a correlation: that people who eat some item, also are healthier in some way. Or a laboratory researcher takes an extract of the food in question and either feeds it to a rat or bathes some tissue culture cells in it, and gets some result that indicates a potentially positive result within the context of the experiment. A media outlet gets wind of this and declares that the food prevents the disease. A food manufacturer finds out that his product is either rich in the nutrient in question, or he has access to a cheap supply of it and begins to fortify his food. The food manufacturer then funds further studies to back up the scientific claim. Then the advertising campaign begins. No where in this process is the health-promoting item in question definitively shown to have any effect on human health with regards to the disease in question. This would require a clinical trial, which is impossible, mostly due to long-term onset of the currently relevant diseases. The whole system is in fact a mass delusion that progress is being made, with all parties acting in good faith. The scientists work with the best models that are available, and assume that their work won’t be taken out of context. The media translates what they view as the interesting facts; the advertisers want to show the best side of their product, and the consumer, who has faith in modern medicine, is just trying to look after his health by eating well, assuming that their information is accurate. Each new ‘discovery’ initiates a fad that in many cases will be reversed by further public health data, such as has recently occurred with the recognition of the positive health benefits of some fats. This would be relatively harmless, except that people end up making poor food choices because they have been convinced that they can make better food choices, and this contributes to the obesity, heart disease, and diabetes that the whole system was set up to overcome. As for me, I’ll stick to worrying about the health of the plants in my garden, and leave my own health to follow their lead.