Monday, January 16, 2012

The Fat of the Land

As a food producer, one of my interests is the relationship between diet and health. In part, this is because I think much of the conventional wisdom concerning the healthiest way to eat is flawed, and iconoclastic positions are exciting things to hold. (Which, in my opinion, can be one of the risks of holding them.) But what I find most fascinating about human diet is the way it highlights the limits of science.

Any dietary change that can improve health outcomes, even slightly, can have a significant positive impact when practiced by a large population. The incentive for organizations, public and private, to promote healthy eating habits is understandable, and the impulse to do so based on incomplete or ambiguous evidence is also understandable, because virtually all evidence in this particular area is incomplete, ambiguous, or both.

A few examples:
1.) Many studies, even the ones that make headlines in the NYT science section, are performed on mice or rats. Often, these mice or rats have been selectively bred for a particular trait, such as a predisposition to weight gain or diabetes. Human metabolism may not be identical to mouse metabolism, particularly selectively bred mouse metabolism.
2.) It is very difficult to establish a good control, particularly with macro-nutrients. For example, in an effort to study diets with a varying amount of protein, scientists might limit total calories to 1600. One group would get 40% of calories from protein, 30% each from fat and carbohydrates. The second "control" group might get 20% from protein, and 40% each from fat and carbohydrates. This would be a particularly poorly designed study, in that all three macro nutrient ratios are different. But even if carbohydrates or fat was kept constant, the other would still have to change to keep the caloric total identical. In other words, there is no way to have a single variable.
3.) Epidemiological studies are always problematic in that the most they can establish is correlation, but with something as complicated as diet, particularly when the studies are based on recalled food intake, they approach meaninglessness.
4.) All humans, so far as I know, suffer to a greater or lesser extent from confirmation bias. Researchers and institutions that have been offering strongly held opinions are likely to discover information that supports these opinions. I certainly view all dietary writing and studies through my particular prism, try as I do to judge them based on their objective merits.

If you're like me, this is about the point in an article when you start wondering what it has to do with gardening.

As previously mentioned on this blog, we have been making an effort to amend the soil of our garden to more ideal ratios, and we would eventually like to remineralize our entire farm. In part, this is justifiable in terms of simple economics - there comes a point at which a lack of calcium will seriously inhibit the growth of a crop or pasture. Yet I still believe it is worth the time to go beyond assuring that the soil has no gross deficiencies, and to make it have as close to perfect as possible a balance of minerals.

There are numerous difficulties.

A few examples:
1.) Soil tests are notoriously variable, based not only on the lab conducting the test, but even due to changing soil characteristics from one month to the next.
2.) There is no universally agreed upon ideal soil profile.
3.) Different amendments, even when providing the same quantity of a mineral by weight, behave quite differently.
4.) Soil is constantly changing - microbiological activity binds up certain nutrients while making others available, roots tap deep mineral sources and draw them to the surface, precipitation leaches each mineral at a different rate, organic matter and mycorrhizal activity in part regulate which of the nutrients in the soil are actually accessible to the the crop or forage.
5.) In trying to translate soil amendment to health, a long, flimsy chain is forged - amend soil (was it properly amended? are the minerals truly available for plant uptake?), grow a crop or forage (what variety? how did the weather conditions alter the quality of the crop?), feed this to a human or animal (all of the issues touched on in the discussion above), and then try to extract some substantial information from the results. William Albrecht's work is the most compelling I've read, but any attempt to deal with issues of this complexity will never be as certain as the link between vitamin C deficiency and scurvy. (And even this clear-cut deficiency disease is significantly more complicated than losing your teeth if you don't eat citrus.)

To me, this is a wonderful state of affairs. Depending on your viewpoint, the world either is or is not completely mechanistic. We have certainly organized large sections of our society around the portions of the world that can easily be mechanized for the sake of huge improvements in efficiency this allows. But what I'm describing, though proposed mechanisms and causal relationships can be speculated upon and doubtless do exist for even so complex a subject as the soil/health relationship, for human purposes, is not mechanistic.

We can take our farm and try one protocol for grazing or soil amending and get great results. But there are so many variables - hundreds beyond those few I've touched on - that it is impossible to foster a delusion that we actually know in the rigorous sense of the term what is going on, to what, if any, extent our actions had a positive result, let alone whether they would have a positive result somewhere else. Certainly, scrutiny and measurement are critical to assessing the impact of an action. But so are intuition, guesswork, gut feeling - all those horribly inaccurate, quite rightly unscientific human traits - and this is immensely enjoyable. There are few areas, let alone critically important areas such as food production, in which specific, unique decision making is practiced so regularly.

I enjoy science a great deal, and I think it is singularly capable of illuminating aspects of how the world works. Even in areas as fraught as diet and soil health, the amount of useful information available is staggering, and I'm grateful to have it. But faith in science is so ingrained that it can easily lead to the assumption that answers exist when they don't. So I will keep testing the soil and amending it in ways that I believe will improve its characteristics, because I believe this will ultimately lead to healthier land, healthier plants, healthier animals, healthier, happier people. Just don't ask me to prove it.



  1. So, I've been thinking about this micronutrient thing, and also about the 'perfect soil'. How do we measure what the perfect soil is, and then how do we get there? It sounds like you’re focused on the ‘how do we get there’ question, but I find myself needing to revisit first question. Is the perfect soil returning the soil to its nutrient rich pre-mass farming time, or is the perfect soil making the soil perfect for what you would like to grow? I’m sure both answers will have a lot in common, but I think the first question may be easier to answer, and more how I would personally idealize as the perfect soil. The first part of that answer will be looking at the native species and animals that were running your land before it was ever farmed, looking at the excrement from those species plant and animal and perhaps that can lead you to your answer, by increasing that biomass and nutrients. The second part of that answer is asking yourself how long will it take your soil to re-enrich itself. Can it happen just by adding in gallons of nutrients at the beginning of each growing season, or will it take years? Testing this theory may be the more interesting part. I’m quite certain that there are particular plants that you will continue growing year after year, and there will also be plants that will be growing during different seasons and to use some of each of those same plants as your ‘baseline’. Measure them for their nutritional value. See what nutrients those plants are taking up and the quantity of nutrients. That may be more science than you would like to get into, but it sounds like your obsessing over it anyway, might as well make it an official study. The third part of the answer, is asking yourself what ‘harm’ does your own farm do to the land? What nutrients are your crops leeching from the soil that you are completely unaware of and how will you compensate? Does composting any waste from your plants and spreading that into your fields return those nutrients that you just took out? Or will you have to compensate with some other plants? What exciting questions you are asking.

  2. Garth- I like the nexus of science and intuition you are exploring.
    I also am relieved you find pleasure in the elusive.

  3. Great post! I would say that you are running into the issues that differentiate knowledge and understanding. Of course, you could take this to be a semantic quibble; but regardless of the terms, I think you are getting at a real distinction. What you are doing is certainly not blind-guest work, but it's not "perfectly rigorous" either (but nothing is and thats the point). Science is truly amazing, but its all the more amazing when you view it from the perspective of know-how, tacit knowledge, and understandings. Scientists are skilled experts who interact with objects (theories, models, equipment) and a lot of this involves intuition, guess work, gut feels, etc. There are genuine "epistemic feelings" that guide our inquiring practices. Of course we strive to adopt rigorous methods when we inquire (tinker or try to figure things out), but we do so within reason and we necessarily take much for granted.

    In short, I will never ask you to prove anything!