Antinutrients – Their Impact on Nutrition

The term “anti-nutrients” suggests what they are. Whereas nutrients are substances that nourish plants
and animals to grow and live, anti-nutrients earn their title because they can block the absorption of
nutrients.


The compounds or substances which act to reduce nutrient intake, digestion, absorption and utilization
and may produce other adverse effects are referred to as antinutrients or antinutritional factors.
Anti-nutrients are naturally found in animals and many plant-based foods. In plants, they are
compounds designed to protect from bacterial infections and being eaten by insects.


There are several compounds in the foods we eat classified as anti-nutrients. Examples include:
Glucosinolates in cruciferous vegetables (broccoli, Brussels sprouts, cabbage)—can prevent the
absorption of iodine, which may then interfere with thyroid function and cause goiter. Those already
with an iodine deficiency or a condition called hypothyroidism are most susceptible.

Lectins in legumes (beans, peanuts, soybeans), whole grains—can interfere with the absorption of
calcium, iron, phosphorus, and zinc.


Oxalates in green leafy vegetables, tea—can bind to calcium and prevent it from being absorbed.
Phytates (phytic acid) in whole grains, seeds, legumes, some nuts—can decrease the absorption of
iron, zinc, magnesium, and calcium.


Saponins in legumes, whole grains—can interfere with normal nutrient absorption.
Tannins in tea, coffee, legumes—can decrease iron absorption.


It is not known how much nutrient loss occurs in our diets because of anti-nutrients, and the effects vary
among individuals based on their metabolism and how the food is cooked and prepared. Many anti-
nutrients like phytates, lectins, and glucosinolates can be removed or deactivated by soaking, sprouting,
or boiling the food before eating.
Combination of Methods
Combining many methods can reduce antinutrients substantially, sometimes even completely.
As an example, soaking, sprouting and lactic acid fermentation decreased the phytate in quinoa by 98%.
Similarly, sprouting and lactic acid fermentation of corn and sorghum degraded phytate almost
completely.


In addition, soaking and boiling pigeon peas led to a 98-100% reduction in lectins, tannins and protease
inhibitors.


The most effective way to reduce antinutrients in plant foods is to combine several different elimination
strategies. Combining methods may even degrade some of the antinutrients completely
Overview
Below is an overview of the main antinutrients and effective ways to eliminate them.
 Phytate (phytic acid): Soaking, sprouting, fermentation.
 Lectins: Soaking, boiling, heating, fermentation.
 Tannins: Soaking, boiling.
 Protease inhibitors: Soaking, sprouting, boiling.
 Calcium oxalate: Soaking, boiling.


Another consideration is that these anti-nutrients affect the absorption of nutrients eaten at the same
meal. Therefore, to lower this risk, it is recommended to avoid eating large quantities of foods
containing anti-nutrients at one meal, and to eat a balanced diet throughout the day with a variety of
foods. For example, instead of eating two cups of bran cereal with milk for breakfast, choose one cup of
cereal with milk and one cup of fresh berries.


People who are at high risk for diseases related to mineral deficiencies, such as osteoporosis with
calcium deficiency or anemia with iron deficiency, may wish to monitor their food choices for anti-
nutrient content. Another strategy could be to alter the timing of eating foods with anti-nutrients.
Examples are to drink tea between meals instead of with a meal to reduce the chances of iron being
poorly absorbed, or taking a calcium supplement a few hours after eating a high-fiber wheat bran cereal
that contains phytates.


Studies on vegetarians who eat diets high in plant foods containing anti-nutrients do not generally show
deficiencies in iron and zinc, so the body may be adapting to the presence of anti-nutrients by increasing
the absorption of these minerals in the gut.

Keep in mind that anti-nutrients may also exert health benefits. Phytates, for example, have been found
to lower cholesterol, slow digestion, and prevent sharp rises in blood sugar. Many anti-nutrients have
antioxidant and anticancer actions, so avoiding them entirely is not recommended.


The takeaway: The pros and cons of anti-nutrients on long-term human health is an area of active
research. Though certain foods may contain residual amounts of anti-nutrients after processing and
cooking, the health benefits of eating these foods outweigh any potential negative nutritional effects.
Eating a variety of nutritious foods daily and avoiding eating large amounts of a single food at one meal
can help to offset minor losses in nutrient absorption caused by anti-nutrients.


Antinutrients can significantly reduce the nutritional value of many plant foods. Luckily, they can be
degraded with a few simple methods such as heating, boiling, soaking, sprouting and fermenting.
By combining different methods, many antinutrients can be degraded almost completely.