Too much dietary manganese could cause staph heart infections, says study

Dietary manganese is an essential mineral found in leafy green vegetables, fruits and nuts.

According to the report, published in Cell Host & Microbe,​ people with excess levels of tissue manganese, including people who take dietary supplements with high concentrations of manganese, may be at risk for staph heart infection.

Staph heart infection is the leading cause of bacterial endocarditis – infection of the inner lining of the heart chamber and heart valves – as well as being the second most frequent cause of bloodstream infections.

‘Super-dosing’ should be considered carefully​

Dr Eric Skaar, Ernest W. Goodpasture Professor of Pathology and senior author of the study, said that it shows people should be careful when taking excessive supplements.

“The human body does a wonderful job of regulating nutrient levels, and a traditional Western diet has plenty of minerals in it. The idea of super-dosing nutrients needs to be given careful consideration.”​

The team used mice to study the effects of dietary manganese on the body.

Results showed that most mice that consumed excessive manganese – three times more than usual – died from staph infections.

“We know very little about how manganese is moved around and regulated. It’s a mystery why high manganese affects staph infection of a single organ,”​ Skaar said.

Furthermore, it was found that excessive consumption of the mineral inactivated defence mechanisms against pathogens.

Skaar explained that in usual circumstances, “neutrophils pour into the site of infection and blast the bacteria with reactive oxygen species”​ in response to staph infections.

However, the excess manganese stops this from happening.

“It’s striking that a single dietary change can inactivate one of the most powerful branches of innate immune defence and lead to fatal infection,” ​Skaar said.

Manganese also prohibits the protein calprotectin from carrying it out its usual protective duties.

Calprotectin acts as a sponge within the body and mops up excess manganese and other metals. However, calprotectin is ineffective in the high manganese hearts. Skaar said it is unknown why this happens.

Skaar and his team are continuing their research on manganese, particularly how it is transported and regulated.

Study: Dietary Manganese Promotes Staphylococcal Infection of the Heart​

Source: Cell Host & Microbe

Published online, DOI: 10.1016/j.chom.2017.08.009​​

Authors: Lillian J. Juttukonda, Evelien T.M. Berends, Joseph P. Zackular, Jessica L. Moore, Matthew T. Stier, Yaofang Zhang, Jonathan E. Schmitz, William N. Beavers, Christiaan D. Wijers, Benjamin A. Gilston, Thomas E. Kehl-Fie, James Atkinson, Mary K. Washington, R. Stokes Peebles, Walter J. Chazin, Victor J. Torres, Richard M. Caprioli, Eric P. Skaar.