الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Vitamin D is known as the ‘sunshine’ vitamin because exposure of the skin to sunlight leads to its synthesis, Vitamin D is a micronutrient that is needed for optimal health throughout the whole life. Vitamin D3 (cholecalciferol) may be synthesized endogenously in the skin via ultraviolet irradiation. Vitamin D may be absorbed from the diet, in the gut, as vitamin D3 or as vitamin D2 (ergocalciferol) vitamin D3 itself is biologically inert.
Vitamin D2 (ergocalciferol) may be synthesized in plants and fungi by the action of UV light on ergosterol. A small amount of vitamin D2 may be obtained from a natural diet. Wild-grown mushrooms are particularly rich sources of vitamin in fact vitamin D2 form of the vitamin is much less effective than is vitamin D3.
Vitamin D fat-soluble secosteroids that are derived from cholesterol.Secosteroids are characterized by a broken bond in one of the steroid rings. The two major forms of the vitamin are D3 (cholecalciferol) and D2 (ergocalciferol), which differ in the structure of their side chains.Vitamin D3 (cholecalciferolDuring exposure to sunlight, UVB radiation (290–315 nm). The synthesis of vitamin D in the skin is the most important source of vitamin D and depends on the intensity of the ultraviolet irradiation which is dependent on season and latitude. Melanin and sunscreen markedly diminish the production of vitamin D. Vitamin D is transported in the blood by vitamin D binding protein DBP to the liver. Vitamin D is hydroxylated to 25-hydroxyvitamin D3 [25(OH) D3]. 25(OH) D3 is the major circulating form of vitamin D. The synthesis of 25(OH) D3 has not been reported to be highly regulated.
Catabolism of vitamin D largely occurs via hydroxylation in the kidney. the formation of calcitroic acid, which is excreted in the bile.
Sun light main source of vitamin D synthesis, dietary sources naturally rich in vitamin D. fatty fish, red meat, offal, egg yolk, Vitamin D2 has been found in some mushrooms, Fortified food with vitamin D. vitamin D may be sourced from dietary supplements.
Vitamin D bioavailability like other fat-soluble vitamins (A, E, K), is absorbed by intestine after that transported in the chylomicrons via lymph to the circulation. The stability of vitamin D3 and vitamin D2 in foodstuffs during cooking has been shown to vary widely with heating process and foodstuffs.
Vitamin D deficiency: Low levels of serum vitamin D may define vitamin D deficiency versus insufficiency. Which osteomalacia may appear. Vitamin D deficiency is a common problem in numerous populations worldwide. Besides its role in calcium and phosphate metabolism, The growing awareness in the medical community that vitamin D deficiency affects large parts of the population and that the consequent health effects go far beyond bone loss and osteoporosis, parathyroid hormone (PTH), neuromuscular function, bone mineral density (BMD) and fracture risk, falls, frailty, Brain outcome, Autism, pre diabetic, Diabetic Retinopathy, bone disorder, Cardiovascular disease, obesity, skin health and cancer.
A potential harm associated with high-dose vitamin D. hypercalcaemia, which could lead to adverse effects such as vomiting, pain, fever, anorexia and weight loss.
Hypovitaminosis D affects almost 50% of the population worldwide Vitamin D deficiency is a global health problem.mortality from heart failure (HF) and cardiovascular disease (CVD) and premature death.
Seafood is a major food worldwide. Seafood consumption for reduction of coronary heart disease, supporting cognitive development and vision and other potential benefits such as the reduction of Attention deficit‐hyperactivity disorder symptoms. Fish isa good source of nutrients associated with prevention of osteoporosis, such as high-quality protein and vitamin D. Fish intake was divided into fatty fish (herring, eel, bourbon, mullets….)and lean fish (Tilapia , sea bream, sole…). Fish is a perfect vitamin and mineral source which can be affected by different cooking methods. Fatty fish are good source of fat-soluble vitamins such as vitamin A (retinol) and vitamin D (calciferol vitamin). The fat-soluble vitamins are less heat-labile than the water-soluble vitamins such as vitamin B1 (thiamine) and vitamin B3 (niacin), but they can be degraded at high temperature in the presence of oxygen Cooking of fish leads to enhanced flavor and taste and inactivation of pathogenic microorganisms. Furthermore, it causes macro and micro nutrients distortion because of their sensitivity to heat, light, oxygen, pH, or a combination of these.
The aim of this study was to evaluate the effect of cooking methods on vitamin D content of some Egyptian seafood meals. Most common available types of seafood (17 type) was used for detection of vitamin D content. Samples were collected from the main central fish market (El-Anfoshy). Samples were freshly collected seasonally. Each type was subjected to the suitable traditional cooking methods (frying, grilling, roasting, steaming.) Vitamin D content was reassessed after each cooking method in triplicates. Vitamin D was detected in edible parts of each sample before and after preparation using High Performance Liquid chromatography (HPLC).
from our results the following can be concluded:
1- All tested fish types contained considerably high content of both vitamin D2 and D3.
2- Traditional Egyptian cooking method that is commonly used for every types offish/shellfish was found to be the most suitable to preserve vitamin D2 and D3in all sample.
7- Marine fish contented much higher amount of vitamin D2 than Fresh fish Vitamin D3 content.
8- Roasting and steaming ( mild and less aggressive cooking temperature ) was the best in preserving vitaminD3 in fatty fish types (fresh water) than lean fish types(marine water).
9- Frying method was the best cooking method for lean fish (marine water) that preserve vitamin D2 content.
10- Grilling method preserve both vitamin D2 and D3 in nearly all samples
11- In Tilapia ,Mirra and sole ,frying method destroy a large amount of vitamin D3 while grilling increased its content.
12- Roasting was the best method that preserve both vitamin D2 and D3content in Mullets, Mayas, eel and Sardine.
13- Fine fish (Besaria) contented the highest amount of both vitamin D2 and D3in raw.Samples the best cooking method was roasting.
14- Coral, red mullets and Besaria contained higher amount of vitamin D3 where prepared by frying than by grilling or roasting.
15- Steaming was the best cooking method for Crabs in which vitamin D3 was higher than that in steaming Shrimps and Scallops.
from the results of this study, we were able to come to the following recommendations:
1- Using traditional cooking method for each fish type is recommended to preserve vitamin D content.
2- Steaming and roasting are recommended cooking methods for fatty fish to keep vitamin D content.
3- Frying recommended for lean fish (marine fish) preparation.
4- Oil that used in frying marine fish is recommended to be reused in preparation of other food items as traditional (Sayadya) ricewhich presented with fish meals (caution should be taken not to use oil in frying for prolonged time or intermittent frying).
5- Obtaining vitamin D for dietary sources is recommended than supplements.
6- A gap exists between the intake and the recommendation of vitamin D. The chronic insufficient intake of micronutrients like vitamin D without seeing immediate clinical signs is called Hidden Hunger. So regular consumption of seafood (fish/shellfish) provide suitable amount of vitamin D.
7- Seafood as healthy food choice is highly recommended which may prevent chronic diseases.
8- Strategies to enrich animal feed with vitamin D in farms of fish, poultry and cows should be implemented.
9- Vitamin D fortification of foods should be encouraged to improve vitamin D intake.
10- Further studies are needed to detect vitamin D in other food groups.
11- Sun light exposure (Heliotherapy; healing power of the sun) is desirable to obtain sufficient vitamin D.