Science in it's infancyWhile modern nutrition is relatively young, 200 or so years, humans have been observing the effects of nutrition and lifestyle on health for millenia. In his book The Paleo Manifesto, John Durant does a great job of describing how religious texts such as the Torah, and the heavy focus on good hygiene, are essentially "scientific" observations of how infectious diseases can spread and rules on how to avoid spreading them. To a person with no access to microscopes and no knowledge of what bacteria are, a bacterial infection would certainly seem like the wrath of God. If you want to avoid feeling God's wrath, it's a good idea to wash your hands, avoid extramarital sexual encounters, avoid touching bodily fluids, and properly inspect your food.
Another early example of science includes the identification of scurvy, a disease of vitamin C deficiency, and the positive impact that citrus fruits had on curing people of the disease. Scurvy was described around 400 BC, but it wasn't until vitamin C was identified in 1932 that we realized that scurvy is a disease of vitamin C deficiency. Scurvy was common among sailors because fruits and vegetables wouldn't keep on long voyages and the grains and cured meats they would eat on these voyages were not significant sources of vitamin C. This brings us to a pretty important point about what we currently know about nutrition; most of it is based on preventing deficiency, not optimizing health.
The RDAs are not optimal intake levelsFast forward to today, and many people believe that the RDAs for vitamins and minerals are optimal dosages, but they're not. The reason we have concrete dosages of vitamins and minerals is because getting less than these dosages leads to disease over time. Health is not merely the absence of disease, many other factors go in to being healthy. Having the energy to go about the day, being happy, and performing in a way that allows you to thrive rather than just survive are necessary components of being healthy.
While having concrete diseases of deficiency such as scurvy, rickets, and beriberi has helped us identify some critical nutrients that we need to survive, it certainly hasn't identified all of them. Vitamin and mineral deficiencies lead to diseases of deficiency in the relative short term(3 years or less). This doesn't mean that there aren't other nutrients that we need that keep us healthy and robust through old age or that prevent us from developing heart disease, depression, anxiety, or sleep disorders as we get older. The direction that society has taken us with regard to science isn't to try and identify what causes these diseases, it has taken us in the direction of what medicine we can take to ameliorate the symptoms of them. I don't know with 100% certainty what causes heart disease, but I do know that it's not a statin drug deficiency. If it were, modern day hunter gatherer tribes would be dropping like flies of heart disease, yet it's relatively rare in their parts.
Deficiency or necessity due to diet?Many of our nutritional problems may not even have to do with deficiency. While I would consider the current Western diet to be pretty dismal with regard to it's nutritional value, there is also the possibility, and strong likelihood, that we are eating foods we shouldn't be eating. A stark difference between our diet and the diet of modern day hunter gatherers is the abundance of processed food we consume. While science gives us numbers as to what level of certain vitamins and minerals is necessary to prevent deficiency, these diseases of deficiency could actually be caused by a diet high in processed foods. In other words, while it may be true that a 20 year old male needs 90mg of vitamin C per day to prevent deficiency, it could also be that this level of vitamin C is only necessary to prevent deficiency in a diet high in processed food since that is the type of diet that was studied when coming up with the RDA. In fact, you don't need to go very far back in history to identify a situation where the consumption of processed food has lead to disease, only about 130 years.
The potential pitfalls of food processingIn the late 1800s, the disease beriberi was rampant in the Japanese navy. Beriberi is a neurological condition that became prevalent in Japan as the processing of rice to increase shelf-life became prevalent. The process of removing the husk from the rice, while extending the shelf-life, also had the unintended consequence of removing most of the thiamin. At the time, scientists had only identified proteins, carbohydrates, fats, and salt as nutrients within food. In 1898, Sir Frederick Hopkins hypothesized that there were other "accessory nutrients" within food that were essential for human health. It turns out he was right, and those accessory nutrients eventually came to be called vitamins and minerals. An interesting fact about thiamin is that it is used for carbohydrate metabolism, and feeding people the high carbohydrate starch found in rice without the thiamin needed to use it is likely what causes beriberi. Thus, your thiamin needs are dictated by your carbohydrate consumption(1).
Most processed foods today are fortified with nutrients such as thiamin to replace some of the nutrients that could be potentially lost during processing. Could the modern processing of food be doing the same thing with yet to be identified nutrients? Who knows, but it is interesting that modern hunter gatherer cultures who don't consume processed foods don't tend to have many of the chronic diseases seen in Western cultures, at least until they begin consuming processed foods.
To be fair, there are may benefits to food processing, but you have to realize there will also be some tradeoffs. In addition, there are other factors that play in to the diseases we see in Western civilization. We are more sedentary and are exposed to far more chemicals than modern day hunter gatherer tribes. We also experience dysfunctional sleeping patterns and are far more stressed than they are. Nutrition is simply one piece of a very large puzzle that we are trying to put together to improve human health. We like to think we have all of the answers, but the truth is we probably don't even have 10% of them because the questions are so complex and complex questions require complex answers. However, you don't always need all of the answers to start making good decisions.
The problem with modern nutritional researchIn a lot of situations, science hasn't provided us with the answers we need to make better choices. However, we can use the science we have and try to fill in some of the holes with things we observe. Like I said earlier, hard scientific certainty is very rare, especially within the nutritional and health sciences. A lot of this has to do with the way we conduct and report scientific research. All scientific discovery begins with an observation, like Isaac Newton's observation of an apple falling from a tree eventually leading to the discovery of gravity or scientists observing that citrus fruits ameliorated the symptoms of scurvy. After these observations, scientists develop theories and run experiments to refine those theories until they come up with an answer. This is how science works, but this is not how it is currently carried out, especially in nutritional science. In the nutritional sciences, we begin and end at the observations and make recommendations based on those. This is why we get so much conflicting research on what is healthy and also why it seems nutritional recommendations seem to change from week to week.
More trappings of observational dataOne week coffee is great for you, the next week it is bad, and the week after that it is great for you again. The reason we see so much flip flopping on what is good for you is because the vast majority of the data we have is observational data. We ask people what they've been eating and doing and we compare their health outcomes to their lifestyle habits to see what may or may not be healthy. Like the apple falling from the tree, observational data is the observation that there is a relationship between two things, not that one causes the other. We rely on this type of data for many reasons. For one, we are looking at complex questions and to run experiments on these complex questions we would need to control variables other than the ones we are looking at to make sure they don't contribute to the results. In the case of nutritional research, this means you would have to pull people out of their every day life, away from their job, away from their family, lock them in a metabolic ward, make sure they all sleep the same number of hours, get the same amount of exercise, experience the same levels of stress, and control their diet to the point that one group gets basically the exact same diet as the other group with the exception of the one variable you are measuring. Who would sign up for that?
Another reason we rely on this data is that most health changes that occur with diet occur over a very long period of time. So not only do you need to control their entire lifestyle, you have to do it over a period of 6-12 months or more for diseases that take a long time to develop such as cancer. So, while we rely on this data out of necessity, we rely on data that really can't do anything other than tell us that people who eat X live longer or are healthier than people who eat Y. Where we run in to a problem is when we have already given out advice without thorough experimentation first. If you tell people that X is a healthy food, people who are interested in being healthy will be more likely to eat that food than people who are unhealthy. People who are interested in being healthy also do other things that are healthy like exercise, get quality sleep, avoid smoking, and limit alcohol consumption. If we don't control for these things, we cannot be 100% sure that this food is actually a healthy choice or if telling healthy people that this food is healthy makes them eat it. This is exactly where we are right now, and is the reason why the science seems to flip flop, it's bad data and not valid for the way it is being used.
Looking at other areas of scienceWhile this puts us in a tough spot, it doesn't put us in a helpless one. The first thing we can do is look at how the human body works and identify areas where we may have gone wrong. Understanding biology and evolution by natural selection can put us on the right path to discovering things that we are more suited to do and eat, and things that may not serve us so well. Identifying the environment we evolved in can help us identify the environment we are most suited to thrive in, or at least identify aspects of the current environment that lead us astray. When I refer to environment, I am referring to lifestyle factors that are necessary for optimal function, not merely your surroundings. This does not mean that we cannot also thrive in another environment, it merely means you need to identify the optimal environment, start there, and work forward rather than just take what you read from observational research and assume it's optimal.
The next thing we can do is look at the lifestyle of groups of people who have better health outcomes than us. If modern day hunter gatherers have a very low prevalence of the chronic diseases of aging and you want to avoid them, what are they doing differently? Obviously they live a life more congruent to the environment we evolved in, what are the things they are doing and which of those things have a mechanism that can affect health. They hunt and gather their food, but is it the process of hunting and gathering or is it that they are far less sedentary and consume far less food than us because they actually have to work to get it? They also don't eat processed food and eat a nutrient dense, lower calorie diet that is very high in fibe(>100g/day). Interestingly enough, we have studies that can shed some light on these traits, both by looking at what happens when hunter gatherers adopt a Western lifestyles as well as studies that look at how genes respond to diet and other lifestyle factors.
While I believe there is more than enough evidence out there to identify the key factors important to optimal health, if you are looking for every hole to be filled in for you, you are going to be very disappointed. As I stated earlier, we really don't have concrete scientific evidence to hold your hand through the entire process. This evidence likely will not come in your lifetime. So does that mean you should just go with the flow and assume all observational data is pointing you in the right direction? I think this is a mistake. If we take the current science that we have, compare it to what we see with healthier groups of people, and scrutinize it from the perspective of what we know about human biology, I think we can get a basic framework of what is healthy and work forward from there.
In the next part of this series, we will take a look at how humans work, specifically with how our cells operate.
How our cells work