- Dietary manganese if exceeds the normal level can cause infection due to Staphylococcus in the heart.
- Excess manganese inactivates a key line of defense of the neutrophils against the bacteria.
- Another line of defense by the protein calprotectin was ineffective in response to elevated levels of manganese.
that is included in the diet from leafy green vegetables, fruits and nuts can
promote infection of the heart by the bacterium Staphylococcus aureus or Staph.This occurs only when
manganese gets accumulated.
The findings, reported in the journal Cell Host & Microbe, add to the evidence that infection can be influenced by the diet. The discovery also suggests, that people who have excess levels of tissue manganese, including those who consume dietary supplements with high concentrations of the metal, may be at increased risk for staph infection of the heart.
"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," said Eric Skaar, Ph.D., MPH, Ernest W. Goodpasture Professor of Pathology and senior author of the current study.
Dietary Manganese and Bacterial InfectionThe impact of staph infection due to dietary manganese was studied by Skaar and his colleagues using a mouse model.
"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," said Skaar.
Excess manganese in the blood inactivates a key line of defense against pathogens. The immune system's response to reactive oxygen was shut down with the excess manganese.
In response to staph, "neutrophils pour into the site of infection and blast the bacteria with reactive oxygen species," Skaar explained. The excess manganese was found to counteract and stop this reaction.
"It's striking that a single dietary change can inactivate one of the most powerful branches of innate immune defense and lead to fatal infection," Skaar said.
Excess Manganese Shuns ImmunityAnother line of defense by the protein calprotectin was ineffective. Usually, calprotectin acts as a sponge to mop up manganese and other metals and keeps these nutrients away from pathogens.
"For reasons unknown, calprotectin is completely ineffective in the high manganese hearts", Skaar said.
Functions of ManganeseManganese is a component of several enzymes and it is vital to the development and activity of several others. MnSOD (manganese-dependent superoxide dismutase) is one of the most important enzymes related to manganese intake.
- MnSOD plays an important role in the management of oxidative stress as it is an antioxidant that transforms toxic radicals into hydrogen peroxide and water.
- Manganese is required for the proper functioning of the brain, and so it is used in the treatment of nervous disorders such as Alzheimer's disease and schizophrenia.
- Manganese helps to regulate insulin from the pancreas, and so a diet that does not include adequate manganese can result in decreased insulin production.
- Manganese supplements are also used to prevent and treat certain types of anemia, and various bone problems.
- Increasing manganese intake may help to alleviate the symptoms of premenstrual syndrome.
Hazards of Staphyloccus InfectionBacterial endocarditis is the infection of the inner lining of the heart chamber and heart valves. Staph is the leading cause of the infection and the second common cause of blood stream infection.
Some populations of people with chronic liver disease and patients on long-term intravenous diets have both increased risk for staph infections, particularly endocarditis, and higher than normal levels of tissue manganese, Skaar noted.
Foods Sources of ManganeseAlthough dietary supplements are more concentrated sources of manganese, it is ideal to know the foods sources to keep a watch on the intake of manganese through diet.
Black tea, cloves, cardamom, spinach, mussels, ginger are good sources of manganese and fruits also contain some amount of manganese.
The study does not highlight the need to reduce the intake of manganese through diet. It is still not understood as to how manganese is transported and regulated in vertebrates, and why the heart is particularly susceptible to fatal staph infections. Further research is being carried out on the impact of other nutrient minerals and vitamins on infection.
- Eric P. Skaar et al., Dietary Manganese Promotes Staphylococcal Infection of the Heart, Cell Host & Microbe (2017), http://dx.doi.org/10.1016/j.chom.2017.08.009.