When you eat foods high in phytic acid, the molecules bind with certain minerals in your digestive tract, including:
Calcium, Magnesium, Iron, Zinc, Chromium, Manganese
Once this occurs, your body no longer has access to these nutrients. Generally, the more phytic acid you eat, the more minerals are blocked from your body.
The highest concentrations of phytic acid are found in raw and unprocessed plant-based foods.
Beans. Most beans and legumes contain a high amount of phytic acid. However, studies have shown that soaking beans before eating them significantly reduces their phytate levels.
Seeds. When a plant is ripening, phytate rapidly accumulates in its seeds. Phytic acid is found in sesame seeds, linseeds, and sunflower seeds.
Nuts. Nuts naturally contain a high amount of phytic acid. The process of “activating” nuts by soaking them in water and then dehydrating them at a low temperature breaks down some of the phytic acid.
Grains. Grains contain phytic acid, but only if they haven’t been processed. Whole grains also contain lectins and saponins, which are two more anti-nutrients. However, products made with processed grains contain fewer healthy nutrients.
Zinc and anti-nutrients
There are substances in foods that inhibit the absorption of some minerals – including zinc – and affect their bioavailability. Bioavailability refers to the amount of a nutrient that is absorbed and goes on to have an effect in the body. These substances that negatively affect absorption of nutrients are known as antinutrients – constituents of food that reduce the nutritional value of other nutrients even though they themselves provide nutritional benefits.
The most notable antinutrient that interferes with the bioavailability of minerals is phytic acid. Phytic acid, also known as inositol hexakisphosphate, is a naturally occurring storage form of phosphorus in plant seeds and the bound form is known as phytate. Oats and flaxseed – two of Huel Powder v3.0’s main ingredients – are both rich in phytic acid. Milling grains and removing the bran decreases the amount of phytic acid in a food and both the oats and flaxseed in Huel Products are finely milled which significantly lowers the phytic acid content of Huel Products.
Phytic acid may be an antinutrient, but it’s also a strong antioxidant with health benefits. It has been shown to be anticarcinogenic and can also bind heavy metals (e.g. cadmium, lead) and helps prevent their accumulation in the body.
The extent as to how much phytic acid reduces the bioavailability of zinc varies and other constituents in food affect the rate. Vegans are at risk of not absorbing enough zinc due to the high amounts of phytic acid in a vegan diet, so it’s suggested that their requirements for zinc are 50% higher than those of meat-eaters. Read more in our article Phytonutrients in Huel.
The effect of phytic acid on zinc, whilst significant, is notably less than its effect on iron, and zinc is also not as affected by other antinutrients as other minerals. For instance, calcium can affect the bioavailability of iron but has been shown to have little effect on zinc status in humans.
A European Food Safety Authority (EFSA) Panel looked at the effect of phytic acid on zinc status. They looked at different levels of phytic acid intake and looked at ranges of zinc requirements from 300mg to 1,200mg of phytic acid per day. They concluded that the Population Reference Intake (PRI) for adult men should be 9.4mg to 16.3mg of zinc per day and for women 7.4mg to 12.7mg per day proportional to the phytic acid intake.