Dietary Diversity: The Forgotten "Vitamin" in Successful Diets

This article is a result of recent discussions with a number of people who practice the Paleo Diet.  For the record, these discussions were polite and the dialogue centered on pursuit of evidence and application of logical actions in the diet.  Grains were a primary focus of these discussions and I pointed out that wild and heirloom versions are not the destroyers of health as some authors have asserted (you can read the article here).  Most pertinent is that real-world observations of wild and traditional people demonstrated certain grains were part of healthy diets, diets that produced vital people and (more importantly) well-formed children.  Modern grains, such as wheat, are a different matter—I concur with restricting or eliminating some of these foods.  As I noted in the previous article, restricting all grains is an over-simplified message.  I would politely argue the real message should be:  eat less grain (i.e., diversify your diet), choose wild and heirloom types, and select gluten-free kinds.

Several people rightly pointed out that grains, even if not detrimental to health, are not as nutrient dense as some animal foods (when all factors are considered).  Though referring to grains as empty calories is highly inaccurate (especially wild and heirloom kinds), the question is still valid as to why we should consume grains at all.  But note, if grains are to be avoided on nutritional grounds, we should extend those arguments (to be consistent) to many nuts, tubers, corms, and other plant foods (foods that demonstrate similar nutritional profiles), eventually limiting our diet to a few of the most nutrient-dense foods we currently know of.  Going even further with this argument, should we, in fact, eat plants at all when animal foods (certain portions thereof) are more nutrient dense?  The answer centers on diversity in the diet.

First, no group of humans consumes only animal foods.  It is an often repeated myth that some arctic cultures ate only animal foods.  This is incorrect and plant foods were very important to them.  For example, the Iñupiat of northwestern Alaska consume many wild plants and even store various species, such as baked-apple berry (Rubus chamaemorus), in seal oil for consumption during the long winter season.  It is estimated that plants comprise only 1% of their diet (calorie-wise) but nevertheless contributes greatly to nutrition as 50% of their vitamin C comes from this 1%.

Two, our understanding of nutrition is still in its infancy and to assume we can rate the quality of a food by adding up its known vitamins and minerals and subtracting out the contribution of its antinutrients is naive (no offense intended).  We (contemporary people) “discovered” vitamin C in 1907, though indigenous people knew how to prevent scurvy long before this.  Essential fatty acids were discovered in 1923, though all known wild and many traditional people had excellent omega 6 to omega 3 ratios without knowledge of these.  We are still battling over the perceived effects of saturated fat and cholesterol (despite a long history of consumption of foods rich in these items by traditional people—people that could, again, produce healthy, well-formed children).  To believe that we, city builders, now must have nutrition all understood because of numerous studies analyzing microscopic components of foods in isolation of the diet (i.e., without context) is really deluding ourselves.  I guarantee that still unknown factors in foods will ultimately be discovered as imparting health (this likely to come from a greater understanding of epigenetics, read on).

Third, and most importantly, indigenous people (including their paleolithic ancestors) consumed a much greater diversity of plants than we do today.  It is an often repeated number that about 30 species of plants are eaten by a typical American in one year.  This number might seem low at first, but you have to consider some important things.  First, many “species” you think you are eating are actually just different cultivated forms of the same plant.  For example, broccoli, Brussels sprouts, cabbage, cauliflower, collard greens, kale, and kohlrabi are all the same species (Brassica oleracea).  Another example, acorn squash, buttercup squash, Hubbard squash, and winter squash are all the same species (Cucurbita maxima).  Another one, pattypan squash, pumpkin, spaghetti squash, summer crookneck squash, and zucchini are all the same species (Cucurbita pepo).  One more, beet root, chard, and sugar beet are the same species (Beta vulgaris).  Therefore, when you create your list of plant species eaten in a year (not in your life), do be sure you are tallying species and not forms of the same species.  As a child growing up in rural Maine, 30 species is fairly close to accurate (certainly people with access to large markets may consume more plant species).

Let’s compare numbers with indigenous groups (who reflect more accurately the numbers consumed by paleolithic people).  The Hausa of west Africa utilized 119 food plants.  The !Kung of Africa ate 85 plants (and 54 animals).  Given that these data were published in late 1960s, we can be fairly certain more species were gathered by the intact culture.  Not to mention, the !Kung live in the northern Kalahari, a water-limited region (which constrains plant diversity).  The indigenous of Tibet were documented to use 168 food plants.  From North America, the Cherokee of the southeastern United States were estimated to consume approximately 80 species of wild plants.  Again, this figure is low because it was published in the 1970s, at a time when much of the botanical knowledge would have been lost (this number reflects what the informants could remember). It also lumps together some species into aggregate groups (e.g., blackberries, hickories).  We can be certain the actual number from the intact culture would have easily exceeded 100.  Even the Iñupiat of far northern North America consumed 40 species of plants (beating out the average American in regard to plant diversity).  None of these counts include medicinal plants that were also ingested and contributed to the phytochemical diversity experienced by humans.  Nor do these counts (save for the one presented for the !Kung) reflect the diversity of animal foods in the diet (which are also substantially greater than that of American diets).  These numbers point to a forgotten aspect of our diets I will refer to as “vitamin V”, the letter v standing in for variety.

What effects do all of this plant diversity have on health?  Many and varied.  Diversity in the diet protects against nutritional deficiencies as different foods contain different amounts and, equally important, ratios of vitamins, minerals, essential fatty acids, and kinds of fiber.  Plants also contain suites of phytochemicals (plant compounds) that act on the physiology of our bodies.  These actions include anti-inflammatory (reducing inflammation), anti-arrhythmic (promoting proper heart beat), hypotensive (lowering blood pressure), antioxidant (scavenging free radicals to prevent cancer, cognitive decline, and premature aging), blood vessel strengthening, antimicrobial (killing pathogenic bacteria, fungi, and viruses), antiparasitic (killing parasitic organisms in the GI tract), antineoplastic (shrinking cancerous tumors), immune system modulation, cleansing the human body through effects on lymph, urine flow, bile, and sweat, and many, many more.  To make this pertinent to grains, studies show that grains do possess polyphenols with anti-inflammatory, antioxidant, anti-aging, antimicrobial, pro-fertility, hypotensive, and anti-cancer properties (these due to a host of phytochemicals, such as various flavones, caffeic acid, and ferulic acid).  Note that polyphenols are not produced by most food animals and polyphenol antioxidants exert free-radical scavenging activity orders of magnitude greater than the vitamin antioxidants found in animal foods.

All of these plant compounds also affect the epigenetics of the people consuming them.  In this manner, the plants we eat alter the expression of our DNA.  In other words, plants (and other foods) direct protein synthesis (the primary day-to-day role of our DNA).  Our DNA receives clues from the foods we eat (and various lifestyle factors) about when to “turn on” and “turn off” protein synthesis.  It is estimated that as much as 30% of our genome is influenced by micro RNAs (i.e., tiny fragments of RNA found in plants), and this is not factoring the nutrition and phytochemistry we receive from plants.  Think of it this way, our ancestry (everyone’s ancestry) has been bathed in a diverse array of phytochemicals from many wild plants in their diets (consumed for both food and medicine).  The magnitude of these effects (given the large number of plants and the incredible diversity of phytochemicals) is still poorly known and under-appreciated.  We clearly know that our food diversity has decreased dramatically (and that cultivated food plant’s phytochemistry has been muted to some degree by breeding).  Emerging research is showing we derive great benefit from plant compounds.  The way to restore this ancestral condition is to eat plants, lots of plants, and many different kinds of plants (along with, of course, animal, fungal, and bacterial foods).  Said another way, maximize your intake of “vitamin V”.

As I wrap up this article, I would like to state (again) that our modern, cultivated produce is very different (in most cases) from the wild plants our paleolithic ancestors consumed.  Keep in mind that along with losses in nutrition and phytochemistry, modern produce has been bred (i.e., genetically altered) to produce more calories per unit mass (at the expense of fiber).  The point:  eating modern produce (of any kind) means you are eating more calories with less nutrition, a recipe for health problems (and children with narrow faces leading to crooked, crowded, and impacted teeth).  To restore deep nutrition (and track paleolithic habits), eat wild plants or cultivated species that are minimally modified from their wild progenitors.  While you seek out plant diversity in the market place or on the landscape, remember that the prohibition on grains, legumes, and nightshades in the Paleo Diet was not practiced by paleolithic people.  This practice (avoidance) appears to be supported by noting the detrimental effects of eating large amounts of modern versions of these plants. However, this argument has serious logical errors.

In summary, avoiding wild and heirloom plant foods because they are considered to be nutrient poor is missing several important aspects of our original diets.  This practice focuses on vitamins and minerals and fails to grasp the tremendous importance (to our evolution and to everyday health) of phytochemistry and the need for phytodiversity in our diets.  All wild and heirloom foods, even those with fewer vitamins than others, play a role in supplying unique kinds and amounts of various plant chemicals that have, literally, shaped our evolution.  Grains are no different in this regard.  A diet rich in small amounts of many kinds of plants can be convincingly argued to be more beneficial than a diet rich in large amounts of few kinds of plants.  Further, any diet attempting to recreate an ancestral diet should focus on diversity (among other factors), for the reasons presented here and all of those we have yet to discover.