DNA Health > Oxidative Stress

Glutathione Peroxidase 1

GPX1 Pro198Leu C>T



GPX1 Gene Detail

GPx1 is expressed in almost all tissues in the body and is responsible for catalysing the conversion of harmful hydrogen peroxide (H2O2) into water (H20) and oxygen (O2) which aren’t harmful. GPx also plays a role in reducing fatty acid hydroperoxides and peroxynitrite using glutathione as a substrate, and thus helps to maintain redox balance. GPx1 is the most abundant of the seleno-peroxidases, and one of the most important selenium-dependant antioxidant enzymes. They also reduce organic peroxides to alcohols, providing another route for eliminating toxic oxidants.



GPX1 Pro198Leu C>T

  • The T allele leads to decreased GPx1 enzyme function and has been linked to a disturbed anti-oxidative balance. If GPx1 enzyme is not working effectively then the harmful build-up of hydrogen peroxide ROS can’t be converted to neutral water.


  • T allele carriers are associated with increased risk for chronic disease, including certain cancers and coronary artery disease especially in the presence of a low fruit and vegetable intake, smoking and high alcohol consumption.
  • There is also evidence that T allele carriers have increased risk of breast cancer with hormone replacement therapy (HRT) use.




As GPx1 uses selenium as a co-factor it is helpful to ensure adequate selenium intake. Brazil nuts are a rich source of selenium, and a regular intake has been shown to significantly increase the activity of the GPx1 enzyme in C allele carriers. One brazil nut contains approximately 70mcg of selenium, (providing over 100% RDA). Include brazil nuts in the diet and other food-rich sources of selenium, such as sardines and turkey. If selenium intake from food is poor, consider supplementation. It is important to note that the C allele is more responsive to dietary selenium intake.

  • Ensure a polyphenol-rich diet with a high intake of vegetables.
  • It is important to moderate alcohol consumption, and to rather drink red wine (due to higher resveratrol levels) as the alcohol of choice. Excessive alcohol intake can reduce glutathione levels and increase oxidative stress.


  • Avoidance of toxin exposure, from heavy metals and pesticides as well as nitrates used as a food preservative, and cessation of smoking should be strongly encouraged.
  • Women carrying the T allele should also be cautious of using HRT.
  • Also, provide adequate intake of glutathione precursors to support glutathione production. A diet should provide sulphur and building block amino acids. Eating beef, chicken and fish should supply adequate sulphur containing amino acids. For vegetarians and vegans the following may provide some sulphur but in smaller amounts: garlic, onion, broccoli, Brussels sprouts, cauliflower, kale, watercress and mustard greens. Some foods naturally contain glutathione however, it is poorly absorbed. Examples are Spinach, avocados, and asparagus.



Serum selenium and single-nucleotide polymorphisms in genes for selenoproteins: relationship to markers of oxidative stress in men from Auckland, New Zealand

Karunasinghe, 2012.