Does consuming foods rich in phytic acid prevent mineral absorption?

Question

I've seen a lot of articles warning that consuming phytic acid can prevent the body from absorbing minerals. They recommend soaking beans, chickpeas, lentils and other phytic acid foods before cooking them.

• The Nourishing Home: How to soak grains for optimal nutrition

Phytic acid is an antinutrient found in grains and legumes which binds important minerals preventing your body from fully absorbing them. Consumption of high levels of phytates:

• results in mineral deficiencies, leading to poor bone health and tooth decay
• blocks absorption of zinc, iron, phosphorous and magnesium
• causes body to leech calcium
• lowers metabolism
• contributes to anemia

• PhyticAcid.org

Researchers have found that if you can reduce the phytic acid in your food, you can improve your iron absorption markedly.

Does the phytic acid in food have a sufficient impact on mineral absorption to cause malnutrition and disease?

Answer 1

Phytates can inhibit (partially prevent) the absorption of non-heme iron from plant foods (but not from meat) by 50% (Linus Pauling Institute), so this question applies more to vegetarians than omnivores.

From the studies below, I conclude that phytates as a single factor do not likely cause mineral deficiencies, but may contribute to them in individuals on poorly designed vegan diets or those with small intestinal malabsorption disorders.

1. GRAS notification for phytic acid, 2011 (FDA.gov)

Significant decreases in the absorption of iron, zinc, magnesium, and calcium were reported in healthy subjects consuming dietary phytate at levels ranging from 50 to 2,340 mg/day in several single-meal and short-term studies.

In contrast, dietary phytate was reported to have no significant effects on iron and zinc bioavailability in longer-term studies (21 days to 6 months).

2. Nakitto AM et al, 2015, Effects of combined traditional processing methods on the nutritional quality of beans (PubMed Central).

The article mentions that sprouting, germination, dehulling, soaking and cooking decreases the phytate content in foods.

3. The article about magnesium on Linus Pauling Institute website does not mention phytates as eventual absorption inhibitors.

4. López-González AA et al, 2008, Phytate (myo-inositol hexaphosphate) and risk factors for osteoporosis. (PubMed)

Phytate consumption had a protective effect against osteoporosis...