Why You Need More Vitamin D

There are few vitamins that have received as much attention in the scientific literature, as well as in the mainstream press, as vitamin D. Its only contender may be vitamin C, the compound that’s found in fruits and vegetables such as lemons and oranges. Vitamin D differs from other nutrients that we humans need to take in in order to function at our best in that it is produced in our skin as a result of sun exposure. It’s also found in some foods; however, sunlight is generally considered to be our most important source of this vitamin, which acts as a hormone inside our bodies.
One of the reasons why vitamin D has received so much attention is that it plays a crucial role in many of the processes that take place inside the human body. A body that is devoid of vitamin D is a frail body: its more susceptible to immune disturbances, infections, and disease than a body that is well-stocked with this powerful compound, given that all other variables are equal. Hence, we clearly have a problem if a lot of people develop a vitamin D deficiency. Unfortunately, this is exactly what has happened in modern times…
Sunny beginnings

The ground zero for the evolution of our kind is Africa. That’s where it’s believed our tree-dwelling ancestors lived, and it’s also where many of the major evolutionary processes of our genus took place. Some member of now extinct hominin species did venture into other parts of the world; however, it is safe to say that Africa is the continent that has played the most important role in shaping the evolution of the human lineage.

Hence, it goes without saying that much of our evolution took place in a very sunny environment. It wasn’t until some 60.000 years ago that members of our species migrated out of Africa and started colonizing the far corners of the world. One of the problems that these early migrators faced was the lack of sunlight in places such as Europe. The skin pigmentation that worked well in Africa didn’t work so well in a cold habitat in which little sunlight appeared.

When compared to a person with light skin, someone with dark skin requires a lot more sun exposure to keep the cellular processes of his body working at a peak level. Hence, it’s not surprising that there has been selection for lighter skin in areas of the world that are far away from equator and where sunlight is scarce.

Most contemporary humans, including public health authorities, unfortunately pay little to no attention to these things and are unaware of the fact that our sunlight/vitamin D requirements were determined in the past as a result of the environmental pressures that acted upon our ancestors.
Most contemporary humans have suboptimal levels of vitamin D circulating in their bodies

In the process of transforming our environment, we’ve stepped out of the milieu in which we evolved to live. As opposed to our primal ancestors, who spent all of their time outside, most of us who live in the modern industrialized world spend the majority of our lives inside closed buildings and vehicles, with the consequence that we are rarely exposed to the sun.

Furthermore, global travel has produced many mismatches in space. Some dark-skinned people have moved to northern countries, such as Norway, where I live, a country where the sun rarely shines, particularly during the winter. The opposite is also true; many people with light skin frequently travel on vacation to sunny parts of the world, where the sun shines brightly, “forget” that their skin is not accustomed to intense sun exposure, and as a result, get burned and eventually wrinkled.

Combine all of that with the many misguided recommendations that are put out by certain public health agencies and authorities saying that no sun exposure is better than some sun exposure, and it shouldn’t come as a surprise that a lot of contemporary humans are exposed to suboptimal amounts of sunlight. In particular insufficient exposure has become a widespread issue, with recent reports indicating that nearly 1 billion people worldwide now have a vitamin D deficiency (<20 ng/mL) or insufficiency (20-30 ng/mL) (1). The figures are particularly concerning with respects to dark-skinned people, with as many as 95% of African Americans having a low level of vitamin D (2). If we add all of the people who have a lower than optimal concentration of vitamin D circulating in their bodies, but not so low that it’s strictly classified as a vitamin D deficiency or insufficiency, the 1 billion number would undoubtedly increase.

Recent research has shown that traditionally living people in East Africa, more specifically the Maasai and the Hadza, have a mean serum 25-hydroxyvitamin D concentration of 115 nmol/l (~46 ng/mL) (3); a concentration that is markedly higher than the one found in most westerners. It’s comparable to the levels measured in Caucasian lifeguards and Hawaiians who spend a lot of time in the sun (3). Whether the mean vitamin D concentration of traditional African populations represents the optimal level for all people is questionable; however, research has shown that it is aligned with the level that is desirable with respect to the prevention of many diseases and health problems, including cancer (4).
Vitamin D deficiency and the diseases of civilization

The consequences of the above problems are multitudinous. Vitamin D plays an important role in many of the processes that take place inside the human body, including several related to immunity, cellular regeneration, bone tissue turnover, and gut homeostasis. There is little doubt in my mind that the vitamin D/sunlight deficiency pandemic has contributed to driving the increased global incidence of many of the diseases of civilization. With that said, it’s important to point out that the results from the studies in this area don’t all point in the same direction. Many studies have indeed found an association between vitamin D levels and various adverse health events (5, 6), but not all (7). This is to be expected, as it can be difficult to assess single nutrient-health relationships.

One important step that we can take to correct this major public health problem is to bring principles of Darwinian medicine into the medical system and the public’s mind. By acknowledging that our vitamin D/sunlight requirements were adjusted over evolutionary time in response to changes in the environments in which we evolved, we can understand how much sun exposure different bodies need in order to function according to their evolutionary design.

In many western countries, the idea that no sun exposure is better than some sun exposure has been allowed to spread, with the result that a lot of people fear the sun. This now common belief has no evolutionary support. It’s obviously wise to avoid getting burned; however, it’s not wise to completely avoid the sun. We have evolved a need for sunlight. It’s true that we can get vitamin D from other sources, such as fatty fish and supplements; however, the sun is in many ways the best source.

Most people in the world today don’t eat much vitamin-D rich foods, and even if they did, they would have to consume fairly large quantities of them to obtain a lot of vitamin D. Moreover, it’s important to remember that vitamin D isn’t the only thing we get as a result of exposure to the sun. Regular sun exposure has been linked to numerous health benefits, including improvements in mood and cognitive functioning. 3, 5

Another often overlooked issue has to do with the dangers of sun lotions. There’s little doubt that sunscreens are useful in some instances; however, I would argue that they are overused. Sunscreens contain many chemicals that the human skin has little or no evolutionary experience with. The evolutionary health model predicts that regular exposure to these compounds could elicit a range of harmful health effects. A growing body of research indicates that this prediction holds true (8, 9, 10). If you have the choice between covering up your body with clothes in order to avoid getting burned and lashing on a concoction of chemicals on your skin that protect it from sun damage, the former option is definitely the preferred one.

it’s important to point out that chronic inflammation, as well as conditions such as diabetes and kidney disease, may inhibit the absorption of vitamin D found in foods, as well as the production of vitamin D from sunlight. This is very important to acknowledge, seeing as many contemporary humans are chronically inflamed and sick, in part because they don’t exercise, consume unhealthy foods, and/or otherwise expose their bodies to novel environmental stimuli that initiate inflammatory reactions. Hence, these people may have to cool down their bodies in order to obtain the full benefits that the sun and vitamin D rich foods have to offer.

A couple of days ago I read a scientific paper by Harvard Professor Daniel E. Lieberman entitled Is Exercise Really Medicine? An Evolutionary Perspective (1). I’ve been a fan of Daniel Lieberman ever since I first read his book The Story of the Human Body: Evolution, Health, and Disease (2), which was published in 2013. I don’t agree with everything he says though. This became increasingly clear to me as I was reading the aforementioned article, in which he makes several statements that I take issue with. There’s one thing in particular I don’t like about his ideology and work: I think he severely underestimates the power of the Paleo diet/lifestyle concept and fails to fully recognize that organismal health plays a critical role in Darwinian evolution

He’s not alone in this regard. I’ve noticed that certain other well-respected evolutionary scientists also seem to be eager to point out in their scientific papers, books, and presentations that the only thing that “matters” in Darwinian evolution is how many reproducing offsprings organisms get, not their health or longevity, and that it’s therefore wrong to assume that one particular lifestyle or environment (e.g., the Paleolithic one) is optimal for Homo sapiens (or any other species for that matter) with respects to health promotion

I don’t fully agree with these assertions. In today’s article I thought I’d briefly explain why…
Healthy organisms are typically more reproductively fit than unhealthy ones

It’s certainly true that variation in reproductive success is ultimately what keeps the process of Darwinian evolution running. What’s important to note though is that organismal health and organismal fitness aren’t unrelated variables. Far from it. The health of an organism may greatly affect its reproductive success. One doesn’t have to possess intimate knowledge about evolutionary biology to understand why this is the case; all that’s required is a basic understanding of how nature works.

An animal that lives in a natural environment and is fit and free of chronic disease obviously has a better chance of surviving and reproducing than a similar animal that is weak, fragile, or sick. This is true regardless of whether the creatures in question are bears, elk, spiders, humans, or any other animals. An animal that is obese, metabolically deranged, or chronically fatigued or has poor eyesight or weak bones most likely won’t make it very long in nature.

Not only that, but the health status of an organism ties in with its libido, sexual attractiveness, and fecundity. This is something that has become increasingly clear to me over the years. People who are chronically inflamed, sick, and/or unfit are not as sexually robust as healthy folks. Not only does chronic inflammation/ill-health impair libido and sexual function, but it also undermines reproductive function (e.g., increases risk of miscarriage and other pregnancy complications) (3, 4, 5, 6, 7).

With this in mind, one can quickly understand why animals that live in the wild, including human hunter-gatherers, are lean, fit, and largely free of chronic disease.
The evolutionary validity of the Paleo diet/lifestyle concept

Unfortunately though, some people, including some scientists, seem largely oblivious to the things I talk about in the previous section. They focus all of their attention on the primary “currency” of evolution – reproductive success – and fail to fully recognize that the value and distribution of another currency – health – greatly affect the value and distribution of the former.

This is concerning, because in order to make sense of what type of diet and lifestyle that is optimal for different organisms with respects to health outcomes, we have to shed light on the health variables that affect organisms’ ability to pass on their genes. It’s also important that we acknowledge that the evolutionary pressures that act on organisms that live in the wild differ in strength, intensity, and nature from those that act on organisms that live in a manufactured environment (e.g., industrialized humans, domesticated animals).

Unlike Paleolithic hunter-gatherers, we – contemporary humans – don’t have to hunt and gather in order to get a hold of food, keep watch for dangerous animals, or bring children into life without medical assistance. Moreover, unlike our ancient forebears, we have access to drugs, eyesight-correcting devices, and modern technology. Hence, not all of the selection pressures that acted on humans in the past act on contemporary human populations, at least not to the same extent. This is very important to acknowledge, because it helps explain why we’re today in the midst of a chronic disease pandemic. Moreover, it implies that we can’t expect natural selection to eliminate disorders such as obesity, myopia, and type-1 diabetes anytime soon. Finally, perhaps most importantly, it helps us make sense of the question of how we should live our lives in order to attain the best health possible.

The primary reasons why the hunter-gatherer lifestyle is so healthful are that natural selection had ample time to adapt our ancestors to their hunter-gatherer niche and that human health and human fitness have been firmly linked throughout most of our evolution. Our ancestors had to compete with other organisms for nutritional resources and “fight to survive”. They didn’t live in comfortably heated, safe homes or have unlimited access to calorie-dense foods. In order to survive and reproduce, they had to be physically fit and healthy enough to get a hold of food, ward of infections, and otherwise survive in the physically demanding environment they found themselves in.
The bottom line

The point I’m trying to make with this article is not that health always tracks closely with reproductive success in the context of Darwinian evolution or that organismal health is the main focus of natural selection. It isn’t. The spotlight of natural selection is obviously directed on organismal fitness. Natural selection will favor traits that are beneficial fitness wise even if they are detrimental health wise. With that said, most of the time (not always), health and fitness go hand in hand. This is particularly true when talking about organisms that live in a natural environment; however, it also to some extent applies to organisms that live in manufactured ones (e.g., domesticated animals, industrialized humans), in part because health and inflammation tie in with libido, sexual attractiveness, and sexual and reproductive functions.

The recognition that we evolved to live in a natural environment, in which one has to be fairly healthy and fit in order to survive and reproduce, is extremely powerful, in the sense that it infers that chronic illness is not an unavoidable part of human life and that we can steer clear of many diseases and health problems by adjusting our environment so that it better matches our evolved biology.

All organisms that are present on this planet are a part of an evolutionary arms race. Throughout evolutionary time, organisms have evolved various apparatus and tools that help them cope with dangers and effectively compete with competitors for limited resources. Humans are no different from other life forms in this respect. Natural selection has equipped us with a variety of different survival tools. Those of our ancestors who possessed tools that worked really well in the environment in which they found themselves were more likely to pass on their genes than those who weren’t as adept at surviving. In other words, the defense systems of the human body have changed in appearance and function over evolutionary time in response to the selective pressures that acted upon our ancestors’ genomes.

Unfortunately, this fact, that all organisms, including ourselves, have various defense mechanisms built into them, is something mainstream medicine largely overlooks. It frequently suppresses, blocks, or tears down people’s defenses, thereby impairing their bodies’ natural ability to ward off dangers. In some instances, drugs are indeed useful; however, more often than not, the drug route is not the optimal route.

I would argue that we should seek to strengthen our bodies’ natural defenses, as opposed to solely focusing our efforts on blocking or suppressing the problems that arise when weak defense systems that haven’t been properly cared for are faced with dangers they find it difficult to cope with.
Bodily defense: One of mainstream medicine’s blind spots

To an evolutionist such as myself, the problems that arise as a result of mainstream medicine’s failure to acknowledge the importance of evolutionary processes in health and disease are clearly visible. You don’t have to look far and wide to find them. They are everywhere. When viewed under an evolutionary microscope, they present themselves as big, inflamed lesions.

I don’t claim to know everything, but if there’s one thing I know, it’s that a clinician who doesn’t possess knowledge about evolutionary theory is grasping in the dark. He will find it very difficult to properly assess what’s wrong with his patients and prescribe the correct treatment. Unfortunately though, most clinicians don’t know much about evolution, in large part because evolution is not something that medical schools pay much attention to.

In the past, I’ve talked a lot about mismatch resolution, microbiome restoration, and several other similar concepts that I believe should be integrated into clinical medicine. What I haven’t talked much about though is the human body’s defensive mechanisms and the role these mechanisms play in health and disease.

A lot of people don’t know that diarrhea, nausea/emesis, fever, and many, many other similar conditions and expulsive events are defenses, not illnesses per se. This isn’t surprising, seeing as these types of discomforts have historically been perceived as diseases or symptoms of diseases, as opposed to bodily defenses. This misunderstanding has come with great costs, in the sense that many clinicians approach the treatment of the above conditions as they would a disease. They prescribe drugs that block the problems, thereby potentially harming their patients’ health. In some instances, it may indeed be necessary to use drugs; however, most of the time, the pros of blocking the defense(s) with a drug are probably far outweighed by the cons.

We humans sometimes overlook the most obvious of things. When we think about it, it’s pretty logical that the above disturbances of bodily homeostasis are defenses, seeing as they all tie in with the immune system in some way or another. Diarrhea typically occurs following exposure to pathogens (e.g., via contaminated food) and is the body’s way of ridding itself of the harmful bugs it has come into contact with. Nausea and emesis often accompany the consumption of food that doesn’t agree with one’s body and act to expulse the food in question and hinder additional consumption of that food. Lastly, fever, which occurs following infection and involves a raise in body temperature, is believed to hinder pathogen growth and speed up infection resolution.

Given that these types of defenses are so integral to our bodies’ immune systems, we should obviously think twice before we hinder their expression. It’s certainly uncomfortable to have diarrhea, be nauseous, or lie in bed with a fever; however, the downsides to taking a drug that eliminates these discomforts prior to their natural disappearance typically far outnumber the upsides.

First of all, if we block these defensive mechanisms with a drug, we may prolong the time it takes for the patient to recover his health. Second, drugs have side effects. In particular drugs with strong antimicrobial properties are problematic, seeing as they are capable of disturbing our microbiotas. If you take an antibiotic when you get an infection, you may clear the infection; however, you may also set yourself up for a whole host of future problems.

Third, our adaptive immune systems are very good at dealing with pathogens and “remembering” what types of weapons that are the most useful for combatting unfriendly microbes that it has previously encountered. If we block the expression of bodily defenses that occur as a result of an infection with a drug, we may in the process interfere with the workings of the adaptive immune system. As a result, we may be unable to mount an optimal defense against a similar infection in the future.
We should listen to what our bodies are trying to tell us

Our primal ancestors faced many dangers. They lived in the wild and didn’t have the option of taking an antibiotic when they got sick; hence, it’s not surprising that we have evolved various defense systems that help us survive in the big, competitive world we live in. A Paleolithic human who possessed a solid defense system and was adept at quickly clearing any potential infections would obviously have been more likely to survive and reproduce than a fragile and immunocompromised Paleolithic human.

As I’ve pointed out many times here on the site in the past, the reason why some people frequently fall sick to the flu, influenza, and other similar conditions is that their bodily defense systems are compromised. They harbor a species-inappropriate microbiota. Instead of trying to develop new drugs that target these conditions and instruct sick individuals to eat x food, take x medicine, or drink x drink when they get sick, I would argue that we should focus our efforts on defense restoration. It’s much better to prevent disease from happening in the first place, as opposed to “letting” them happen before we deal with them.

Not everyone is willing to put in the effort it takes to solidify their bodily defenses though. Moreover, the process of building a strong and healthy body is rarely straight-forward. Some people are not able to attain excellent health due to genetic factors. Finally, there’s only so much one can prevent. Even a healthy person does get sick from time to time. Pretty much regardless of what we do, we can’t completely eliminate the possibility that we come in contact with food-borne pathogens or encounter other dangers that throw us off balance.

When a disturbance does happen, we should think twice before we block the actions of the defense systems that evolution has equipped us with. These systems are there for a reason. They are much better designed than the drugs we humans create. We shouldn’t necessarily completely exclude the possibility of taking a drug; however, we should explore other avenues before we consider going the pharmaceutical route.

This brings us over to the key point I want to make with today’s article: things happen for a reason. Instead of running down to the drug store and buying a jar of pills every time we get sick, we should probably stop for a second and think about what it is our bodies are trying to tell us.

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