Answer to Question 1
Vitamin A deficiency poses a serious health concern around the world. The World Health Organization (WHO) estimates that 250 million preschool children worldwide have vitamin A deficiency disorder (VADD)the majority being in developing countries. Health problems related to this nutrient deficiency are immensely important to overall health worldwide. Of particular concern is the effect of VADD on morbidity and mortality rates from severe illnesses, such as malaria. VADD is common in regions of the world where malaria is endemic, and vitamin A supplementation decreases both incidence and severity of this disease.
Current strategies to combat VADD worldwide include supplementation, food fortification, and education regarding the importance to health of vitamin A-rich foods. In addition, the WHO recommends vitamin A supplementation at the earliest possible opportunity after 6 months of age in many regions of the world where VADD is common.
Another strategy being explored to reduce the incidence of VADD is the use of biotechnology or bioengineering to produce crops (genetically-modified organisms, or GMOs) with higher levels of vitamin A. For example, because rice is a poor source of vitamin A, VADD is common in many areas of the world where people rely on rice for most of their calories. In the late 1990s, German and Swiss researchers produced a genetically-modified rice plant that synthesizes -carotene. This rice, later named Golden Rice, provides -carotene to the diet, whereas ordinary processed rice does not. More recently, a strain of rice called Golden Rice 2 has been developed, and contains 20 times more -carotene than the original Golden Rice. These nutrient-dense foods can be used effectively to prevent and treat VADD and a multitude of other nutritional deficiencies worldwide.
Answer to Question 2
It is true that higher circulating levels of lutein and zeaxanthin, nonprovitamin A caroentoids, have been related to decreased risk of age-related deterioration of the retinaa disease called macular degeneration. (Macular degeneration affects the macula, the highly sensitive portion of the retina needed for central vision.) Many studies suggest that carotenoids exert their effects on the macula by positively influencing the immune system. However, though research shows that consuming high amounts of carotenoid-containing fruits and vegetables is associated with a reduction in many chronic diseases, it does not show the same effect for carotenoid supplements. In fact, dietary intervention trials often suggest a negative effect of carotenoid supplements on health. Some studies have shown that carotenoid supplements increase the risk for lung cancer in some individuals. Scientists believe that the health-promoting effects of fruits and vegetables may be due to carotenoids working in synergy with each other and/or with other nutrients found in foods.
If consuming fresh fruits and vegetables is problematic, perhaps Mrs. Greeley's daughter could explore with her various ways that Mrs. Greeley could increase her consumption of canned and cooked fruits and vegetablessuch as in casseroles, soups, and salads. -carotene may be more bioavailable as a result of processing and heating.
Some male birds and mammals congregate in communal courting grounds called leks.
This image shows growing blood vessels in the retina of a mouse
Mold is growing on red/green agar in a divided Petri dish.
The upper intake manifold, often called a plenum, attaches to the lower intake manifold.
Rice noodles are a good gluten-free substitute for pasta