Smokers need more vitamin E
the vitamin is used up more quickly than in non-smokers to fight
off the damage done by cigarettes.
It has been known for some time that cigarette smoking reduces blood levels of vitamin C, and it also appears to sap folate levels, but the data were less clear on vitamin E.
Scientists at the Linus Pauling Institute at Oregon State University have found that among people with similar diets, blood plasma levels of the nutrient dropped 13 per cent faster in smokers than in non-smokers.
The controlled study, published in the American Journal of Clinical Nutrition, also revealed an important interaction with vitamin C, showing for the first time how inadequate levels of this vitamin can cause further and faster depletion of vitamin E.
Together, the findings demonstrate how smoking might cause cancer, and how the loss of these antioxidant vitamins can play a role in this process, say the scientists.
"Cigarette smoke is an oxidant, creating free radicals that are associated with increased oxidative stress, cell mutations, and can lead to such diseases as cancer, heart disease and diabetes," said author Professor Maret Traber, an expert in vitamin E.
"In lung tissue, vitamin E is one of the first lines of defence against the free radicals generated by cigarette smoke."
In 2003, 34 per cent of Europe's population were estimated to be smokers although major public health campaigns, as well as a ban on smoking in public places in some countries, could reduce this number. The habit kills more than 650,000 Europeans a year and costs EU states about €100 billion annually.
The US researchers believe that vitamin E is being depleted from smokers' tissue concentrations in order to keep up its levels in the blood, leaving the tissues - including those of the lungs - particularly vulnerable to attack by toxins and free radicals.
"The liver has a protein that helps to regulate blood concentrations of vitamin E, and while the blood plasma levels may be the same, it appears the tissues are being depleted," said co-author Richard Bruno.
"Our research makes it clear that smokers must receive more vitamin E than non-smokers in order to achieve the same overall levels in the body. If the blood levels are the same, and vitamin E is leaving the blood faster, then the tissues must be depleted."
Smokers also need more vitamin C to help slow the decline of vitamin E, suggest the researchers.
They believe that vitamin E often plays the first role in intervening against free radicals and preventing membranes from becoming oxidized - but in the process, vitamin E itself can be made into a radical. If adequate vitamin C is present, it can help the vitamin E return to non-radical form.
But without adequate levels of vitamin C in the body, vitamin E in tissues can quickly decline, Traber said.
"Smokers with the lowest vitamin C levels have the fastest disappearance of vitamin E," she explained.
Vitamin E must be present before free radical damage occurs, however, and cannot be expected to repair all the damage when consumed later. Yet reduced intake of oils and fats is thought to have caused a decline in intake of the vitamin among many western populations.
