We must eat in order to live, since we need extraneous building blocks and nutrients to metabolize and convert into energy (ATP, adenosine triphosphate) and other vital end products for our cells to function properly. We are able to use some endogenous material as part of these building blocks, such as nonessential amino acids, but most have to be taken from our external environments – oxygen mainly via respiration and all other nutrients from the diet.
We are organisms that are composed of organic matter, namely carbon, oxygen, hydrogen and nitrogen. The function of breathing provides us with the number one essential nutrient, the aforementioned oxygen, which we inhale and absorb via the lining of the lungs. Since our body is composed of nearly 70% water (H2O, hydrogen monoxide), we also need to provide the body with water to replenish that which is lost via urination and perspiration (both of which are waste removal mechanisms). The rule of thumb is that a human being can survive up to three minutes without breathing, three days without water, and three weeks without food (of course, longer records have been set, but these are the average ballpark figures). So that goes to show you the relative importance of breathing, drinking and eating.
So now that we all agree that eating is vital to our survival and proper function, let’s look further into how we can nourish ourselves with the most high quality nutrients. As stated above, we are mostly composed of organic matter, which translates into our biggest nutritional needs for macronutrients: carbohydrates (including fiber), proteins, and lipids (fats). These nutrients can come from both plant and animal sources. The rest of our needs are filled by micronutrients, the “micro” referring to the much smaller amounts needed in proportion to the macros.
Micronutrients encompass the vitamins (vitamins A, D, E, K; vitamin C, variety of B vitamins, etc.) and trace minerals (Calcium, Magnesium, Selenium, Zinc, Boron, etc.). Vitamins can be subdivided into lipophilic (fat-soluble) and aqueous (water-soluble), and may differ vastly in structure and function from one another, without any affiliation under their abstract grouping.
Theoretically, most vitamins and minerals can be obtained by eating a varied diet that includes spices, herbs, and “superfoods.” A few vitamins, such as vitamin B12, choline, and omega-3 are much more easily obtained and readily absorbed from animal/fish sources, but in general most have adequate availability in plants (at least as precursors which can then be converted into a usable form in the body). The active form of vitamin D (cholecalciferol) is only provided by sunshine to be absorbed via the skin, while all other sources have the ergocalciferol precursor which need vitamin A and K2 coenzymes for proper absorption.