Vitamin A: technology and applications

Feasibility and Use of Vitamin A–Fortified Vegetable Oils among Consumers of Different Socioeconomic Status in Thailand

Background

Vitamin A losses in fortified vegetable oils can differ, depending upon the cooking and distribution conditions of a country.

Objective

To determine vitamin A losses in different vegetable oils during transportation, cooking, and storage among consumers of different socioeconomic status.

Methods

Soybean, rice bran, and palm oils were fortified with vitamin A palmitate at 267 μg/15 mL. The oils were packaged in 5-L metal cans and 250-mL polyethylene terephthalate (PET) bottles and then stored under light and dark conditions. Unopened and opened bottles were stored for 13 and 4 weeks, respectively. For- tified palm oil also was bulk transported in trucks and packaged in 1-kg polypropylene bags that were closed with rubber bands. Vitamin losses were measured after cooking at 120° and 170°C for 5 and 10 minutes in iron, aluminum, Teflon, and glass pans.

Results

Vitamin A losses of oils in PET bottles stored under light conditions were 20% to 25% at the 5th week and became greater than 80% after 13 weeks, whereas losses under dark conditions and in metal containers were less than 15%. Loss during bulk transportation was 25%, with no change in peroxide value. Losses in opened bottles after 4 weeks under light conditions were 50% to 90% based on the degree of oil unsaturation; however, losses under dark conditions were less than 5%. Losses after cooking at 120° and 170°C for 10 minutes were less than 5% and 15%, respectively. The type of pan did not affect the amount of loss. The peroxide values of oils in bottles increased during storage under light conditions.

Conclusions

Fortification of vegetable oils with vitamin A for consumers of different socioeconomic status is feasible; however, light protection is needed for better stability.

Retinoic acid stimulates growth hormone synthesis in human somatotropic adenoma cells: characterization of its nuclear receptors

In order to gain a better understanding on the possible role of retinoic acid (RA) on human GH secretion, we have characterized the expression of its nuclear receptors in somatotropic adenoma cell extracts. By immunoblotting with rabbit polyclonal antibodies directed against RAR alpha, beta, and gamma and RXR alpha and beta, we could only detect the presence of RAR alpha and RXR alpha proteins. The predominant expression of RXR alpha was confirmed at the mRNA level by Northern and slot-blot analysis. We then investigated the effect of RA on GH synthesis in cell culture of adenomatous somatotrophs. In cultured cells, RA (1 microM) stimulated GH secretion, increased intracellular GH content and GH mRNA levels within 72 h, suggesting a modulation of GH synthesis by RA.

Carotenoids and retinoids in human nutrition

Since the discovery of vitamin A as a fat-soluble growth factor in the early part of the century, research into carotenoids and retinoids has attracted the attention of many scientists. These two groups of compounds are still being actively studied all over the world since many gaps in knowledge exist and new frontiers are being pursued. Recent developments in studies into the possible roles of carotenoids and retinoids beyond their classical functions in vision have created a great deal of excitement in the biomedical community. This review covers a wide range of topics pertaining to these two closely related compounds. Particular emphasis is given to the functions of these compounds and their roles in human nutrition. Various aspects of vitamin A deficiency and studies on carotenoids and retinoids in cancer development and prevention are reviewed in some detail.

Legume carotenoids

In recent years, the results of research studies have suggested a positive beneficial relationship between a vegetarian-based diet and low incidence of diseases, including coronary heart disease, cancer, obesity, dental caries, and osteoporosis. beta-Carotene has specifically been suggested as a nutrient with antitumorigenic properties. In this regard there is a need to evaluate the carotenoid content of foods. Legumes are one of the staple components of a vegetarian diet. This review specifically surveys the prevalence of carotenoids in food and forage legumes. In addition, the methods available for carotenoid analysis are discussed; factors affecting the determination of carotenoid content during maturation, germination, processing and storage are identified; research areas which have been inadequately explored are identified; and suggestions are made for future lines of investigation.