NEWCASTLE, England, November 23 /PRNewswire/ -- We mustn't protect ourselves against consuming too much beta-carotene, but rather against consuming too little! This was the conclusion recently drawn by leading experts in the fields of medical and nutritional science at the 2nd Hohenheim Nutrition Conference in Stuttgart, Germany. Dr. Georg Lietz of the internationally renowned Newcastle University reported that the general population in the United Kingdom and other European countries is not obtaining sufficient beta-carotene through diet alone and thus cannot benefit from the essential health promoting functions offered by the vitamin A precursor. Vitamin supplements and foodstuffs enriched with beta-carotene can be a good and safe way to insure adequate vitamin A intake. Concerning the repeated discussion of the safety of beta-carotene, Prof. Hans K. Biesalski of the University of Hohenheim, Germany, explained that the only potential for danger existed in the case of extremely high doses of supplements consumed by heavy smokers, although even for this segment of the population a daily consumption of up to 10 mg would still be harmless.
In the 1990s, beta-carotene came under fire from critics when two studies revealed that the consumption of large amounts (10 to 15 times the recommended daily intake*) over years of this carotenoid had led to an increase in the risk of lung cancer and mortality in heavy smokers or workers exposed to asbestos. The scientific community, which at that time was hoping that with beta-carotene they had discovered a miracle cure for the adverse health effects of smoking, was very disappointed, explained Biesalski No negative effects have been observed in non-smokers. For them, pro-vitamin A is absolutely harmless and beneficial to health if consumed at physiological concentrations, as is also the case for smokers taking moderate doses up to 10 mg.
Beta-carotene - essential for vitamin A supply
Beta-carotene is extremely important as a precursor (pro-vitamin) of vitamin A, which the body requires, for example, to keep immune defenses functioning well. The National Diet and Nutrition Surveys (NDNS) have shown that a large number of the British population does not obtain enough preformed vitamin A through food and that this gap needs to be closed by sufficient amounts of beta-carotene, a vitamin A precursor.
The British Nutrition Foundation (BNF) recommends a daily intake of between 0.7 to 1.5 mg of vitamin A (retinol) for healthy adults in the form of 'retinol equivalents', which also include pro-vitamin A. To achieve this value, a daily intake of 2 to 4 mg beta-carotene is recommended. On average the general British population remains well below these recommendations and is thus susceptible to wide-ranging health risks. This is due to the fact that a majority of the population still does not eat enough fruit and vegetables (natural sources of beta-carotene), liver or other sources of vitamin A.
Vitamin A deficiency through beta-carotene-dependent gene variants
In addition, the research team of Dr. Lietz furnished the first indications that approximately 40 percent of all Europeans possess a gene variant that restricts the amount of beta-carotene their bodies can convert into vitamin A. Many experts doubt that the current conversion factor of 1:6 (to form one molecule of vitamin A, six molecules of beta-carotene are necessary) is realistic. There is much evidence that suggests the ratio is actually 1:12, which would require a recommended daily intake of approximately 7 mg of beta-carotene to reach the vitamin A recommendations if current low intakes of preformed vitamin A are not changing. If the gene-related restrictions on the utilization of beta-carotene are taken into account, says Dr. Lietz, then the daily recommendation would need to be even higher for those who carry the genetic variation. Further investigations in this direction are currently underway.
Sufficient beta-carotene/vitamin A supply can prevent infectious diseases
In the discussion that followed, there was much talk of ensuring adequate beta-carotene/vitamin-A intake to strengthen the immune system and to prevent colds in particular, especially during this cold and wet time of year. In the skin, beta-carotene protects against the damage that can result from intense exposure to the sun by neutralizing the photo-oxidative stress, according to Professor Helmut Sies of the Universitatsklinikum Duesseldorf, Germany. The ultimate goal, according to Dr. Lietz, is a balanced diet, although any possible gaps (e.g., insufficient amounts of fruit, vegetables and liver) should be covered with nutritional supplements and enriched foods to increase the intake of vitamin A.
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Dr Georg Lietz, School of Agriculture, Food and Rural Development, Newcastle University, tel: +44(0)191-222-6893 or email firstname.lastname@example.org
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