A Crash Course in Nutrition

A Crash Course in Nutrition

There are two basic categories of nutrients: micronutrients and macronutrients. Macronutrients include carbohydrates, fats and proteins, all of which can can be broken down into energy. Micronutrients include vitamins, minerals, fibers and phytochemicals. Micronutrients perform a variety of functions, but do not supply the body with energy. Lets take a look at the different kinds of macro and micro nutrients, and what specifically they do.

Of the three macronutrients, most of us get most of our energy from carbohydrates. There are two kinds of carbohydrate: simple and complex. Simple carbohydrates are sugars like sucrose and fructose, which are molecules of carbon, hydrogen and oxygen. Complex carbohydrates are complex, strung together chains of sugars. The body’s preferred source of fuel is glucose, which is a simple carbohydrate. Naturally-occurring carbohydrate dense foods include: cereals, grains, and fruits. Fibers are also technically carbohydrates, however, since the calories our body gets from them are minimal, and they provide other functions, we will treat them as a micronutrient. Carbohydrates (excluding fiber) have four calories per gram.

Proteins consist of chains of amino acids. For our body's purposes, there are two kinds of amino acids: essential, and non-essential. The body can create non-essential amino acids, but it cannot create essential amino acids; these it must get from food. There are nine essential amino acids, seven of which can be broken into glucose to be used for fuel in a process called gluconeogenesis. However, the body only uses amino acids for fuel as a last resort, as amino acids provide a variety of important functions, such as the creation and maintenance of cells. Naturally-occurring protein dense foods include meat, milk and eggs. Like carbohydrates, proteins have four calories per gram.

Fats are primarily composed of carbon and hydrogen, and serve as a dense store of energy. There are a variety of different kinds of fat but they fall into two basic categories: saturated and unsaturated. Like proteins, there are fats that the body can make on its own, called non-essential fatty acids, and those it must get from dietary sources, which are called essential fatty acids. There are only two kinds of essential fatty acids: omega three fatty acids, and omega six fatty acids. Like protein, fats perform a variety of functions, and play a vital role in the creation and maintenance of cells. Fats can be used as fuel in a process called ketogenesis, which breaks stored fat down into ketone bodies, which the body can then use for fuel in the absence of glucose. Some naturally-occurring fat-dense foods are: milk, nuts, and avocados. Fat is more than twice as calorie dense and protein and contains nine calories per gram.

Vitamins are organic compounds that the body needs to perform various metabolic processes. There are thirteen vitamins required by the human body, which come in two varieties: fat soluble and water soluble. There are four fat-soluble vitamins (A,D,E and K); the other nine are water-soluble (the eight B-vitamins, and vitamin C). The body can store fat soluble vitamins, but not the water soluble ones. The body acquires most of its vitamin requirements from dietary sources, but can create some vitamins itself, such as vitamin D, from sunlight, vitamin K from gut flora, and niacin by synthesizing it from the amino acid, tryptophan.

Minerals are inorganic elements, which fall into two nutritional categories: major minerals, which your body needs a lot of, and trace minerals, of which the body only needs small amounts. The major minerals are calcium, phosphorus, potassium, sodium, and magnesium; any other minerals the body requires, such as iron or selenium are trace minerals. Both major and trace minerals are required for growth, immune support and variety of other functions that keep our cells and organs working properly. The body cannot synthesize minerals, so it must acquire them from dietary sources.

There are two kinds of fiber: soluble and insoluble; and they both serve critical functions. Soluble fiber is a mechanical cleaner that keeps the intestinal tract free of debris. Non-soluble fiber serves as food for the microbiome that lives in the gut and keeps the digestive system healthy. Fiber also regulates the digestion of simple sugars, preventing spikes in blood sugar. Both kinds of fiber add volume to our food and promote satiety.

Phytonutrients are plant chemicals. Although often overlooked, phytonutrients play an important role in promoting optimal health. There are thousands of phytonutrients, and they perform a variety of functions, like reducing inflammation and oxidative stress, and preventing disease.

For the stone-age hunter-gatherer, if she obtained enough calories, she would have gotten enough micronutrients as well. Her diet would have included only unrefined, organic, whole-foods. Modern humans, on the other hand, may go days, weeks, or longer eating nothing but processed foods. Eating foods dense in macronutrients and lacking in micronutrients is arguably the single biggest cause of sickness and disease in developed nations--the other contender being smoking cigarettes. According to the World Health Organization, the leading causes of death in high income countries are as follows:

1. Heart disease
2. Stroke
3. Alzheimer’s and other Dementias
4. Lung Cancer
5. Pulmonary Disease
6. Lower Respiratory Infections
7. Colon and Rectum Cancers
8. Diabetes  
9. Kidney Disease
10. Breast Cancer

Of these ten diseases, seven can be ameliorated, prevented, or even reversed by a eating a whole-foods, plant-based diet (and all of them if you avoid smoking cigarettes as well). Being healthy is simple: keep the meat and animal products to a minimum, and don’t eat refined foods.

Refinement means anything that you do to alter a natural food, like grinding, drying, freezing, heating, removing or adding parts and chemical alteration. As a rule, the less refinement, the better: a baked potato is healthier than a bag of chips; cocoa beans are healthier than milk chocolate; and whole wheatgrass is better than brown bread is better than a dinner roll is better than a cookie. Of course, no one in their right mind is going to bring a bag full of grass to work for lunch--some refinement is to be expected, but it should be kept to a minimum.

If we want to get more specific, than just “whole-foods, plant-based” we should take a closer look at each major category of food. That way we can understand why, for example, it's usually better to eat a salad than a bag full of nuts...

Under normal circumstances, there are no better foods than vegetables. They contain a good mix of carbohydrates, proteins and fats. Additionally, they are extremely micronutrient dense; they are rich in vitamins, minerals and phytonutrients. Since most of their bulk comes from water and fiber, you can eat as much as you want and never become overweight. Until you arrive at your ideal weight, the more vegetables you eat, the slimmer you’ll become. If you love to eat, vegetables are for you; most people would find it very challenging to get their daily caloric requirement by eating raw vegetables alone. Cooked vegetables make the task easier, but 2000 calories worth of cooked vegetables is still a massive amount of food. There is no better way to revitalize an undernourished body than to load up on vegetables. Regularly eating ten servings of vegetables per day, whether cooked or raw, is a guaranteed way to look and feel your best. The high fiber and micronutrient content makes vegetables extremely nutritious and satiating and they are simply too voluminous to allow for overeating.

Fruits are also extremely micronutrient dense, and like vegetables, most of their mass comes from water and fiber. However, fruits are more calorie-dense than vegetables. Usually, the majority their calories come from simple carbohydrates. Fruits usually contain little fat and less protein, although there are exceptions, like the fat-rich avocados and olives. In the age of processed sugar, fruits are undervalued and under-eaten. Most people like sweets but will usually chose a slice of chocolate cake over a fresh apple. Despite having a more complete nutritional profile than chocolate cake, the humble apple has an advantage: because it contains soluble fiber and other micronutrients, its sugars are released gradually. This means the body has enough time to metabolise those sugars properly and avoid the host of health problems that come from eating sugary processed foods.

Nuts and seeds, are high in fat, generally low in carbohydrates, and contain a good amount of protein. Nuts and seeds are less micronutrient dense than fruits, but because they contain so much protein, they make a good complement to fruit. When eaten on their own, it’s easy to overeat nuts and seeds. They don’t contain any fiber, even if you eat a much smaller volume of nuts and seeds than fruits and vegetables, you will absorb more calories. Fruits and vegetables are good at making you feel full, but not always good at making you feel satisfied. Because nuts have such a high fat content, they are satiating in a way that fibrous foods are not, which is a good reason to eat them in combination with fruits and vegetables.  

Beans, pulses and legumes are often overlooked by the meat-eater, but are a must for the vegetarian or vegan. They contain lots of protein, little carbohydrate, and very little fat. They tend not to have the micronutrient density of vegetables, but they are higher in caloric density, and contain a good amount of fiber. It’s true that beans, pulses and legumes usually don’t, by themselves, contain uniform amounts of all nine essential amino acids, but they can easily be combined with other foods to balance out this discrepancy. For example you can complement beans with rice, or pasta with cheese.

Meat and seafood are very nutritious foods. They can contain large amounts of fat, as is the case with red meat; a small amount, as with chicken breast; or almost none, as is the case with white fish. Meat always contains a large amount of protein and no carbohydrates. Meat always contains large quantities of all nine essential amino acids, and some vitamins and minerals that can be harder to get from plant sources. Wild fatty fish like salmon are very high in omega threes, which as you'll recall are essential fatty acids, and are important for optimal health. Meat doesn’t contain fiber or phytonutrients. Although it’s usually not considered healthy, it is possible for human beings to live entirely off of meat. Whether it’s best to eat no meat, some meat, or a lot of meat is a big topic, which we will address later on.

Eggs and dairy are nutritionally similar to meat. They contain high amounts of protein, and fat, and little to no carbohydrate. Additionally, like meat, they contain no fiber or phytonutrients.

Finally, we come to cereals and grains. Cereals and grains come from grasses. They are high in carbohydrates, but also contain some protein and fat. Whole grains have quite a good micronutrient density and contain both fiber and phytonutrients. Cereals and grains, and in particular, rice and wheat, provide human beings most of their calories and are therefore an indispensable part of the human diet. Grains and cereals are not the most nutritious foods, but they are the most available, which is probably why breads and cereals group made up the base of the old food pyramid.

Cereals and grains have long been a staple food for humans and our evolutionary ancestors. Since we began to leave the rain forest and move into the savanna more than three million years ago, most of our lineage have come to rely more and more on grasses for their calories. But, if modern primates are any example, our original diets must have been a huge variety of vegetation, insects, the odd bit of honey, and perhaps, occasionally, meat.

As our ancestors, homo-neanderthalensis, homo-erectus, and finally homo-sapiens left Africa and spread to the four corners of the Earth, our diets and our bodies have adapted to suit all its various environments. From the frozen mountains of Scandinavia, to the teeming jungles of the Amazon, to the scorched deserts of the Arabian Peninsula, man has carved out his niche, and adapted a diet to suit his environment. Such is our adaptability that we can live on a diet of mainly fish and game; a cornucopia of hundreds of plants and animals; or camel milk and dates, with the occasional bit of meat.

The human diet varies wildly from region to region, and our ethnicity probably has some bearing on which particular diet suits us best. Some may claim, that the diet best for them is mostly meat and little of anything else. Perhaps this is true; as we now know, the body can create energy from fat and protein, and acquire or create many vitamins and minerals without eating fruits and vegetables. Some even claim that vitamin C is not necessary for a diet that doesn't contain carbohydrates, eliminating the risk of scurvy.

However, most of us thrive on a variety of different foods and in particular, vegetables. We need to eat a lot of them, but they are the most nutritious foods as they contain the highest concentration of micronutrients, lots of water, and an excellent balance of all three macros.

Whatever we choose to eat there are some rules that apply to all of us: the fresher the better, eat organic if you can, and avoid processed food as much as possible.