Friday, June 19, 2009


The connection between healthy eye and vitamin A is well known and WHO is in the forefront in global attempts to prevent blindness amongst children through massive program for administering this vitamin to children with high vulnerability to its deficiency. Being a fat soluble essential nutrient, people from poorer segments of the society find it difficult to buy nutritionally adequate vitamin A rich foods in their daily diets. Mothers suffering from such a deficiency cannot be expected to deliver babies with normal vit A levels. Though milk is fortified with vit A and D in many countries for supplementing the quantity consumed through the diet, in India this is not followed by the organized dairies and therefore milk is not a good source of vit A. While whole milk contains only about 15 ug of vit A per 100 ml. to compound the problem further, the native vit A is removed partially during processing when fat content is generally brought down to 3% in standard milk. Fortification of processed foods is not practiced widely in India by the industry and this makes the vit A deficiency a serious problem to be addressed.

Retinol, Retinal, Retinoic acid and Retinyl esters are different forms of vit A with differing activities and most common sources are animal products like eggs in which it is present as retinyl ester while plant sources like carrots and spinach have pro-vit A carotenoids which are converted into active forms either by hydrolysis or by cleavage. The ratio of conversion of carotene to vit A is 21:1 calling for large quantities to be consumed for getting the recommended daily allowance. An adult needs daily about 900 ug of vit A equivalent to 3000 IU in terms of retinol but the tolerance limit is up to 10000 IU. Vit A plays important role in vision, especially night vision, bone and teeth development, health of the skin and mucous membranes and also as a powerful antioxidant in the body. Synthetic vit A acetate and palmitate are water soluble and can be incorporated in food products with good stability. It was in 1933 that the critical role of vit A in vision was discovered and ever since that blindness management became easier with this vitamin therapy. Vitamin A which is an alcohol gets converted to the active retinal, its aldehyde form during the complex photo reaction associated with vision.

Different sources of vit A differ in their yield of the active principle in the body when ingested and a common precursor of vit A, carotene can provide less than 5% active chemical for use in vivo. This uncertainty makes it difficult to predict the efficacy of various sources in producing vit A in the body. Saffron, an herbal spice, has been reported to be effective in improving health of the eyes by scientists in Italy though the exact mechanism is not known yet. This cost prohibitive flower material is produced largely in Iran which accounts for more than 95% of world production. It contains more than 150 phytochemicals, identified so far but the major ones are alpha crocin, picrocrocin, saffranal, crocetin, many other carotenoids like xeaxanthine, lycopene, alpha and beta carotenes, many volatile as well as fixed oils. Which component is responsible for the eye health yet to be elucidated. The health protecting abilities of saffron have been known for the last 3000 years and are well documented. Crocin and crocetin were found to improve memory and leaning skills and arrest neurodegenerative disorders. Saffron in general is believed to aid digestion, ease colic problems, lessen stomach discomfort, give relief to flatulence symptoms, protect from cancer and mutagenic risk and serve as immunoregulatory and antioxidant agents. The new findings give saffron another magical property viz protecting eyes from damage of direct exposure to strong sun light and consequent retinal stress apart from slowing down macular degeneration associated with normal aging process. It also influences genes which regulate the fatty acid content in the cell membrane and thus makes vision cells tougher and more resistant.

As saffron use in foods is self-limited because of its use for coloring and flavoring qualities, no safe dosage has been established scientifically. A 5 gm intake is considered the outer limit though this itself is an over dose. 10 gm or more can cause miscarriages in pregnant women and 20 gm can cause kidney damage, central nervous system paralysis and possible death. Generally it is agreed that an intake equivalent to 6-10 stigmas can provide all the beneficial effects ascribed to saffron.Considering that saffron is sold at prices varying from $500 to $5000 per pound in the international market, consumer may find it difficult to decide on the quality parameters based on which it can be purchased. No wonder saffron was associated with rich people like Cleopatra, Alexander the Great, ancient Greek and Roman royalties as only they could afford this luxury material for their personal use. High prices also leads to wide spread adulteration with similar looking flower stigmas and other inedible materials, posing a real threat to consumer health. Adulterators do not even spare the God if one is to believe that TTD temple at Tirupati which uses substantial quantities of saffron for its Laddu prasadam finds it difficult to source pure saffron! Will mortals do better? God knows!


1 comment:

Michael Edson, MS, L.Ac. said...

Vitamin A supplementation is particularly important for people with retinal issues. For example, research supports taking 15,000 IU per day of Vitamin A for those with Retinitis Pigmentosa.

Vitamin A is a necessary structural component of rhodopsin or visual purple, the light sensitive pigment within rod and cone cells of the retina. If inadequate quantities of vitamin A are present, vision is impaired.

The 11-cis retinal form of vitamin A is essential for the neural transmission of light into vision.

A deficiency of vitamin A causes a deficit in the pigment needed by rod cells (responsible for our night vision). As a result, if fewer rod cells are able to sufficiently respond in darker conditions, night blindness can result.

Betacarotene is the water-soluble version of vitamin A (which is fat soluble), and can be converted to Vitamin A by the body as needed.

Food sources for betacarotene include yellow and orange vegetables, including yams, carrots and sweet potatoes, asparagus, spinach, butternut squash, kale, bok choy, mangoes, cataloupe and apricots.

Top sources of vitamin A include: beef liver, egg yolk, cheddar cheese and fortified milk.

Eye exercises can also help maintain strong and healthy vision.

For more information on nutrition and vision, go to Natural Eye Care