Nutritional science has essentially assumed the opposite: ONLY essential nutrients are important, and nutrition should focus on designing diets to make sure that there are sufficient quantities of these nutrients.
Leave out the word “focus” and it is hard to argue with them.
However, consider this possibility:
The most important nutrients in the body are nutrients that the body makes. They are so important that the body cannot leave the achievement of a proper level of them to the chance of eating this food or that on any particular day or week.
Consider the nutrient taurine as an example. If a vegan is not making enough of it, his/her food supply is not providing any. Serious deficiencies could result. Dairy and most meats supply only some taurine. Seafood is very high in taurine, but not that much consumed in America. Only beef, among common meats, is really high in taurine. With such a limited supply of taurine generally in foods, what are the chances that even a carnivore is getting enough, if his body is not producing enough?
And here’s the rub – really bad things happen when the body no longer makes the right amount (either too little or too much) of these CRITICAL nutrients, making these nutrients “conditionally essential.”
In other words, so-called conditionally essential nutrients are CRITICAL nutrients, and are more critical to health than essential nutrients.
The problem is made worse because we almost never know what our conditionally essential nutrients are, and consequently, can do nothing about them, except eat a balanced diet and make every calorie count toward nutrition.
Essential nutrients are ones that are generally readily available in food supplies and so the body has no need of making them. The rub here is that wacky diets, unsuitable for omnivores – diets that overemphasize plant or animal sources, or that unnaturally limit either fats, proteins, or carbohydrates – can lead to essential nutrient deficiencies, medical conditions, diseases, and eventually death, if the deficiencies are extreme enough.