"This is the first study of its kind and confirms... that plastics ultimately reach the human gut" said Dr Philipp Schwabl, the lead researcher who presented the findings at the United European Gastroenterology meeting.
"While the highest plastic concentrations in animal studies have been found in the gut, the smallest microplastic particles are capable of entering the bloodstream, lymphatic system and may even reach the liver. We need further research to understand what this means for human health."
Microplastics are particles of plastic less than 5mm and are used in various products.
They also form when large pieces break down through weathering, degradation or wear and tear.
Microplastics - shed by everything from synthetic clothing to road paint - are present in 83 per cent of tap water samples, all German beers and even in European rainwater, studies show.
Experts fear that microplastics in the body may damage the immune system, trigger inflammation, and can help carry toxins such as mercury or pesticides into the body.
In sea mammals, it is believed plastics damage fertility.
The study looked at eight individuals from Finland, Italy, Japan, the Netherlands, Poland, Russia, the UK and Austria.
Their food diaries showed that all were exposed to plastics during the week either by consuming plastic-wrapped foods or drinking from plastic bottles.
Six of them consumed sea fish, that often consume microplastics.
Dr Stephanie Wright, a research fellow at King's College London, said: "The fact that so many different polymers were measured suggests a wide range of contamination sources. What is of concern is whether this size range reflects our true exposure, or if smaller sizes are being retained or are able to cross over the gut wall.
"What may be of greater concern for these large microplastics, is whether any associated chemical contaminants leach off during gut passage and accumulate in tissues."
