Taking a daily supplement of vitamin E could cause thinning of the bones, new research has found.
Researchers from Keio University in Tokyo performed laboratory tests on rats and discovered that vitamin E stimulates bone-degrading cells that weaken the bones.
The study found that alpha-tocopherol, the most common form of vitamin E, released low levels of ‘resorption’ – the osteoclast process where bone minerals are broken down and recycled in the body, promoting bone generation.
The alpha-tocopherol compound in vitamin E was not good at ‘remodelling’ the formation and breakdown of bones, thinning the bones as a result.
The study found that lab mice with low blood levels of vitamin E, grew excessively thick bones. This was down to their body being poor at breaking down old bone (resorption), rather than building healthy new bones.
Lab mice given alpha-tocopherol vitamin E supplements at does equivalent to the amount taken by humans, experienced a 20% reduction in bone mass after just eight weeks.
Poor resorption levels is linked to osteoporosis, where bone is broken down quicker than it is being replaced, resulting in weakened bone structure.
However, researchers added that the same effect did not occur when animals were given the less common form of vitamin E, delta-tocopherol.
Previous research has indicated that alpha-tocopherol is beneficial for bone health but researchers from Keio University pointed out: “Most of these studies used a small sample size and were not well controlled."
Dr Takeda, who led the study, said in a statement, reports the Press Association: "In summary, we show that vitamin E stimulates bone resorption and decreases bone mass by inducing osteoclast fusion. Moreover, we provide evidence that serum vitamin E is a determinant of bone mass.
"Given the widespread use of vitamin E, and especially alpha-tocopherol, as a supplement in humans, a larger, controlled study that addresses its effects on human bone is warranted."
In the UK, around 3m people have osteoporosis, causing 1,150 deaths a year. Osteoporosis is caused when old, broken down bones are not renewed by resorption.
Bones stop growing in length between the ages of 16 and 18, but bone density continues to increase slowly until a person is in their mid-20s. At this point, the balance between bone demolition and bones construction stays stable.
However, bone loss becomes more rapid as we grow older as the bones density decreases, particularly in women several years after the menopause. Osteroporosis increases the risk of a bone fracture in the wrists, hips and spinal bones.
Vitamin E is commonly taken by many for its powerful antioxidants qualities. It protects the body's natural vitamin A from being destroyed by damaging oxidation radicals. The vitamin also helps protect skin cells by slowing the cell deterioration process associated with ageing as well as protecting against cancer, heart disease and strokes.