POISONOUS AND HEALTHY!

Otago Daily Times, Issue 21540, 12 January 1932, Page 10

POISONOUS AND HEALTHY!

VITAMIN D A Berlin message, of November 24, in the St. Louis Post-Despatch, says:— Pure vitamin D is poison as well as a life-saver. This discovery is explained‘as one result of the “ isolation ” of a crystal which is pure vitamin D, announced last week by Professor Adolf Windaus. Isolation means that the vitamin has been separated completely from all the other substances in which it ordinarily exists. Professor Windaus has a fragment of it in absolutely pure form. He refused to discuss his discovery, which required four years’ research, but he named as spokesman Professor Carl Oppenheimer, a Berlin editor of scientific publications. “ The physiological effects of the vitamin thus isolated,” said Professor Oppenheimer, “ are the same as those of sunshine. Three-billionths of a gram of the cystal is sufficient to relieve rickets, the diet disorder which is caused by vitamin D deficiency. But one fifty-thousandth part of a gram is poisonous. It remained questionable hitherto whether the poisonous effects of vitamin D were derived from the vitamin, due to too high a dose, or whether they came from some other substance that was merely mixed with the vitamin. Now everything is clear.’ The pure crystal was obtained by use of certain rays of “ artificial sunshine. ’ It began several years ago when the scientific world took notice at the discovery that either artificial or natural ultraviolet rays of light acted on cholesterol to produce vitamin D. Cholesterol is a substance related to rare alcohols and is distributed widely in growing things. Professor Windaus, however, learned that it was not the cholesterol that changed into vitamin D. The vitamin came from another substance, crgosterol, which always accompanied the presence of cholesterol. Next, he found that certain wave lengths of ultra-violet transform about 50 per cent, of crgosterol into vitamin D and that the remaining 50 per cent., which is not vitamin, is easily removable. A striking feature is that the wave lengths making this 50 per cent, conversion are those which naturally reach the earth in sunlight. They are the ultraviolet rays down to 2900 angstrom units this unit being the scientific measuring roil for light impulses. Both artificial light and the sun produce ultra-violet ravs much shorter and more powerful than the 2900 kind, but those from the sun are filtered out by the atmosphere before reaching the earth’s snrtacc. When the vitamin thus created by light has the useless half removed, part of the remaining vitamin crystallises of its own accord. The remainder of the vitamin can be crystallised by treatment with _ a ■chemical anhydride of citraconic acid. This process appears to remove sonic sort of by-product, which serves to prevent full crystallisation. The vitamin crystals absorb ultra-violet light most strongly at 2650 angstroms. This means that the vitamin has a special affinity for ultra-violet rays of that specially high power.