A study of human poo from around the world has found evidence of microscopic plastic particles swallowed in food.

In every sample investigated, scientists discovered tiny particles of up to nine different types of plastic.

Experts believe plastic in the gut could suppress the immune system and aid transmission of toxins and harmful bugs or viruses.

Lead researcher Dr Philipp Schwabi, from the Medical University of Vienna in Austria, says that's of particular concern to patients with gastrointestinal diseases.

The smallest microplastic particles are capable of entering the blood stream, lymphatic system and may even reach the liver.