Humans require three things to survive: oxygen, water, and food. We can live only a few minutes without oxygen, and only a few days without water. We can live much longer without food (up to three weeks, in some cases), but the quality of the food we eat—and most importantly, the nutrients it contains—is what determines whether we simply survive, or thrive.
There are two types of nutrients in food: macronutrients, which include protein, carbohydrates, and fat, and micronutrients, which are vitamins, minerals, and other compounds required in small amounts for normal metabolic function.
The nutrient density of foods refers primarily to micronutrients and amino acids (the building blocks of protein). Carbohydrates and fats are important to health, but, with the exception of two fatty acids, they can be provided by the human body for a short amount of time if dietary intake is insufficient. The same cannot be said for micronutrients and the essential amino acids found in protein, which must be obtained from the diet.
Humans require about forty different micronutrients (i.e. vitamins, minerals, and trace minerals) to function properly. In fact, every single process that happens in the body— from your eye blinking to your heart beating to your brain comprehending this sentence you’re reading—depends upon these micronutrients. When you don’t get enough of them, your body can’t function as it should and disease begins to develop.
Unfortunately, nutrient deficiency is widespread even in the relatively affluent industrialized world. More than half of Americans are deficient in zinc, calcium, magnesium, vitamin A, vitamin B6, and vitamin E, according to a 1997 survey. Approximately one-third are also deficient in riboflavin, thiamine, folate, vitamin C, and iron. In many cases, these aren’t mild nutrient deficiencies; up to 50 percent of Americans consume less than half of the recommended daily allowance (RDA) for several micronutrients.
This is especially alarming when you consider the fact that the RDA is based on the amount of a nutrient required to avoid acute deficiency symptoms. It does not reflect the amount required to avoid deficiency symptoms over an extended period. This amount is not known for most micronutrients, but it is almost certainly higher than the RDA, which means that an even larger percentage of Americans than the number given above are not getting enough of these vitamins and minerals.
Because nutrients fuel all processes in the body, nutrient deficiency affects literally every cell, organ, and tissue. Nutrient deficiency is associated with a long list of problems, including:
- Weakened immune function.
- Premature aging.
- Cancer and cellular damage.
- Cardiovascular disease.
- High blood pressure.
- Lipid (cholesterol) abnormalities.
- Depression and anxiety.
In truth, it’s almost impossible to find a health condition that is not associated with nutrient deficiency, given the importance nutrients play in maintaining optimal function.
The importance of bioavailability
It’s not just the amount of nutrients that a food contains that is important, it’s how bioavailable those nutrients are.
Bioavailability refers to the portion of a nutrient that is absorbed by the body. The amount of nutrients we absorb from a food is invariably lower than the absolute amount of nutrients the food contains.
The nutrients in some foods are more bioavailable to humans than others. For example, the grass on your front lawn is loaded with vitamins and minerals, but they’re largely inaccessible to humans. Grass contains large amounts of a plant fiber called cellulose, which humans cannot break down. Since we can’t break down the cellulose, we can’t absorb the nutrients grass contains.
On the other hand, nutrients in animal products like fish, meat, poultry, dairy, and eggs are highly bioavailable. This means we can absorb them easily.
The key to nourishing your body, then, is to maximize your intake of bioavailable nutrients. This will ensure that your body has everything it needs to function optimally.
The nutrient density and bioavailability of foods
The table below ranks foods according to their nutrient density and bioavailability.
|Organ meat||Whole grains*||Refined grains (i.e.bread, |
pasta, crackers, etc.)
|Meat, wild game and poultry||Legumes*||Sugar|
|Fish and shellfish||Plant fats and oils**||Industrial seed oils|
|Eggs||Animal fats and oils**||Processed food and snacks|
|Fruits||Dairy products||Sugar-sweetened beverages|
|Nuts and seeds*||Alcohol|
|Herbs and spices||Natural sweeteners|
* Whole grains, legumes, and nuts and seeds contain substances called “nutrient inhibitors” that impair the
absorption of some of the nutrients they contain.
** Plant and animal fats are relatively low in nutrients, but they play other crucial roles, including helping us
to absorb the nutrients in other foods.
If you study the table above for a moment, you might notice several interesting things.
First, all of the most nutrient-dense foods are real, whole foods, and all of the least nutrient-dense foods are processed and refined foods. In Step 1: Eat Real Food, I argued that processed and refined foods are destroying our health because they promote overeating and inflammation, and inflammation is at the root of all modern disease. Here we see yet another problem with these foods: they are at the bottom of the scale in terms of nutrient density.
Second, you might be surprised to see that organ meats, meat, fish and shellfish are in the highest category of nutrient density. In fact, when the major nutrients required for human function are considered, these foods are even more nutrient-dense than fruits and vegetables. One serving of beef (about 3.5 ounces) typically contains more B12, niacin (B3), vitamin D, retinol (vitamin A), zinc, iron, potassium, phosphorus, and EPA and DHA than the same amount of blueberries or kale, which are two of the most nutrientdense plant foods. In addition, the nutrients in meat are highly bioavailable when compared to foods like cereal grains, nuts and seeds, and legumes. The bioavailability of zinc, for example, is four times higher in meat than it is in grains.
But wait a second, you say! Shouldn’t we be avoiding red meat because it clogs our arteries and increases the risk of cancer? While early research studies did suggest a link between red meat consumption and these conditions, more recent studies (that were larger and better designed than the previous ones) have found no connection at all. If you’d like to learn more about this, I’ve written an entire series of articles debunking the myth that red meat is harmful.
Third, while neither animal nor plant fats are especially nutrient dense, they do play other important roles in the diet. Perhaps most importantly, they help us to absorb the nutrients that are present in other foods. We will revisit healthy fats in Step 3.
Finally, look at where whole grains and legumes are on the table; they’re not the nutritional powerhouses you may have been led to believe they are. Not only do they lack important nutrients, but they also contain substances called “nutrient inhibitors” that make it more difficult for us to absorb some of the nutrients they do contain.
Traditional cultures who ate a lot of grains and legumes went to great lengths to break down these nutrient inhibitors so they could better absorb the nutrients in these foods. These methods included soaking, sprouting, fermenting, and leavening. If you have the time and energy to prepare grains and legumes in these ways, and you tolerate them well, there’s no reason they can’t be part of a diet that emphasizes other more nutrientdense foods like meat, fish, eggs, and fruits and vegetables. (Likewise, if you eat nuts and seeds, you should soak and then dehydrate or roast them first in order to increase the bioavailability of the nutrients they contain. See this article to learn more.)
- Emphasize nutrient-dense, whole foods like meat, organ meat, fish and shellfish, eggs, fruits and vegetables, nuts and seeds, and herbs and spices.
- Minimize your intake of flour, sugar and other sweeteners, industrial seed oils, and processed and refined food and snacks of all kinds.
- Eat healthy fats. Though fats aren’t especially nutrient-dense, healthy fats are an important part of the diet because they play several other important roles, including helping us to absorb nutrients we get from other foods.
- If you choose to eat nuts, grains, and/or legumes, it’s best to soak them prior to cooking to maximize nutrient bioavailability.