Basic nutrition series, part 4 – Nutrient density, Bioavailability and Antinutrients

By Turun Kiropraktikkokeskus

Part 4: Now that we know our basics about calories, macronutrients and micronutrients, there are a few phenomena that we must take into consideration when it comes to the food we absorb… as opposed to the food we eat.

What is nutrient density?

Let’s start with what we call nutrient density. This measurement refers to the concentration of essential micronutrients and amino acids in a given food. Remember that the word essential in this context means that such nutrients can not be synthesized by the body on its own and must be obtained from our diet. Foods that are considered to be nutrient-dense are those that contain a high concentration of these essential nutrients in proportion to their total calories.

In general, nutrient-dense foods are vegetables, fruits, whole grains, legumes, nuts and seeds and certain meats and dairy products. For example, vegetables like spinach, broccoli, and kale are considered to be particularly nutrient-dense because they are low in calories but high in vitamins, minerals, and fiber. On the other hand, foods that are high in calories but low in essential nutrients, such as processed snacks, sugary drinks, and fast food, are considered to be nutrient-poor, although hypercaloric. Does that mean that we should only eat foods which are low on calories? No, remember that it is relative to the amount of nutrients the food contains. We should still consume the optimum amount of calories our body requires.

Eating a diet that is rich in nutrient-dense foods is important for overall health and wellness as it provides the body with the essential nutrients it needs to function properly. By focusing on nutrient-dense foods, you can ensure that you are getting the most nutrition possible out of each calorie you consume, which promotes optimal health and reduces the risk of chronic diseases. To make sure that we do absorb and benefit from such nutrients, we have to take advantage of their bioavailability too.

What is bioavailability?

Although nutrient density is crucial, it would be pointless without taking into consideration the bioavailability of nutrients. This concept very specifically refers to the portion of a nutrient that is absorbed in the digestive tract and makes its way into the bloodstream for the body to use. The bioavailability of a nutrient depends on how easily it can be broken down and absorbed by the body. For example, some nutrients are more readily available in animal products than in plant-based foods. Iron in red meat is more easily absorbed by the body than iron in spinach, because the iron in spinach is bound to compounds that can interfere with absorption. Same thing applies to the calcium in spinach, from which only about 5% is actually bioavailable, although spinach is considered nutrient dense.

What are antinutrients?

Any compound impairing nutrient absorption is referred to as anti-nutrient. Even if they are not widely accepted as inherently bad and can be argued to have some health benefits, consuming large amounts of foods that contain high levels of anti-nutrients can cause nutrient deficiencies to develop, modify our gut microbiota, and be detrimental to health.

Here are some examples of anti-nutrients and how they act:

  • Phytic acid is a naturally occurring compound found in grains, nuts, seeds, and legumes and can bind to minerals such as zinc, iron, and calcium, making them less available for absorption by the body. This can lead to mineral deficiencies if these foods make up a large portion of the diet.
  • Oxalic acid is found in spinach, swiss chard, beet greens, rhubarb, chocolate, nuts, and seeds, and can bind to calcium, iron or magnesium, forming insoluble oxalate crystals. Oxalic acid is mostly known to reduce the absorption of calcium and potentially lead to kidney stone formation in susceptible individuals.
  • Lectins are a type of protein that binds to carbohydrates and are found in legumes, grains, and some vegetables. They have the ability to interfere with nutrient absorption by binding to the lining of the digestive tract, causing inflammation, and potentially damaging the gut lining. The aforementioned complexes interfere with digestive enzymes and impair nutrient absorption such as iron.
  • Tannins are polyphenols found in tea, coffee, red wine and some fruits and can inhibit the absorption of multiple nutrients through the formation of insoluble complexes. Tannins may have an increased binding affinity to iron, and may lead to iron-deficiency, anemia and other nutrient deficiencies.

Note that we can counteract anti-nutrients in several ways. One of the primary ways is by breaking down the anti-nutrients through heat and other cooking processes, such as soaking, sprouting, steaming or fermentation. For example, soaking grains, legumes, and nuts in water before cooking can help to reduce their levels of phytic acid and other anti-nutrients. Cooking can also make certain nutrients more bioavailable by breaking down their surrounding complex structures. For example, cooking tomatoes can release more lycopene, an antioxidant that is associated with various health benefits, than eating raw tomatoes, and cooking cruciferous vegetables like broccoli and kale can make them easier to digest.

In conclusion

We should be conscious of the hidden nutrients and anti-nutrients in our food, and find the best strategy to absorb all the essential macro and micronutrients that we need to thrive!