While studying egyptian anthropology, lino was surprised to learn that zinc deficiency was common among certain middle eastern populations, even though their diet was high in zinc-containing foods. this is because high levels of in unleavened bread limit the bioavailability of zinc from this dietary staple.

The correct answer is - phytic acid.

Explanation:

Phytic acid is a small molecule that available in various food such as seeds, beans, grains, and nuts that chelates specific minerals like iron, zinc, magnesium, and calcium.

High level of phytic acid in individual animals or humans like middle eastern populations even though they had a high amount of zinc in their diet. The high level of the phytic acid decreases the bioavailability of the nutrients and minerals.

Thus, the correct answer is - phytic acid.