Writing in the journal Free Radical Biology and Medicine, researchers have shown that vitamin E is essential in the repair of the plasma membranes of cells – meaning that without an adequate supply of the vitamin cells cannot repair properly after damage.
That could be a big problem for many cells, such as muscle cells, which get membrane tears just from being used, said the researchers behind the study – led by Dr Paul L. McNeil at the Medical College of Georgia at Georgia Regents University.
"Every cell in your body has a plasma membrane, and every membrane can be torn," said McNeil – who noted that muscle cells are constantly torn simply through being used.
"Part of how we build muscle is a more natural tearing and repair process - that is the no pain, no gain portion - but if that repair doesn't occur, what you get is muscle cell death. If that occurs over a long period of time, what you get is muscle-wasting disease," said McNeil – who also suspects that knowing the cell membrane repair action of vitamin E has implications for muscular dystrophy, and common diabetes-related muscle weakness, as well as traumatic brain injury.
Vitamin E and health
The association between vitamin E and healthy muscles is well-established; for example, mammals and birds deprived of the vitamin experience muscle-wasting disease, which is in some cases lethal.
Indeed, a poor diet resulting in low vitamin E levels in the elderly is suggested to contribute to frailty, muscle weakness, and being more unsteady. As a result, and because of the vitamin's well-established role as a powerful antioxidant, it is commonly used in anti-aging products.
However, exactly how vitamin E protects muscle, as well as other cell types, had been unknown until the new findings.
"This means, for the first time, 83 years after its initial discovery, we know what the cellular function of vitamin E is,” commented McNeil. “And knowing that cellular function, we can now ask whether we can apply that knowledge to medically relevant areas.”
In their study, the US-based researchers fed rats either normal rodent chow, chow where vitamin E had been removed or vitamin E-deficient chow where the vitamin was supplemented. First, there was a period of training to ascertain the rats' innate ability to run downhill on a treadmill – which is a challenging move for muscles, and is known as eccentric contraction.
This exercise helps lengthen muscles and can produce the most soreness in athletes because of the high mechanical stress as the muscle contracts and lengthens simultaneously.
In their study, McNeil found vitamin E-deficient rats were generally deficient in their running ability compared with controls, and made significantly more ‘rest’ visits to a grid area - despite the fact that they received a mild electric shock when they stood there.
The team also administered a dye that could not permeate an intact plasma membrane, and found it easily penetrated the muscle cells of vitamin E-deficient rats, but not other rats.
McNeil noted that a healthy cell makes a patch within a minute and has completely restored the cell membrane within a few minutes.
Further examination of the quadriceps muscle fibres under a microscope showed rats fed normal chow or chow where vitamin E had been restored were essentially the same, meanwhile the muscle fibres in rats fed vitamin E-deficient chow were smaller and inflamed.
McNeil's finding that vitamin E is essential to rapid cell membrane repair, and ultimately cell survival, likely holds up across different cell types because, in culture at least, when the scientists have treated a number of different cells types with vitamin E, they documented similar enhanced cell membrane repair.
"The major medical significance here is yet to be uncovered," McNeil said, adding that the findings could one day mean that supplements do not just aid muscle building for athletes but may also be used to help sluggish membrane repair in diseases such as muscular dystrophy, and could be a preventive therapy for high-risk individuals such as astronauts or soldiers.
Source: Free Radical Biology and Medicine
Volume 84, July 2015, Pages 246–253, doi: 10.1016/j.freeradbiomed.2015.03.016
"The antioxidant requirement for plasma membrane repair in skeletal muscle"
Authors: Mohamed Labazi, et al