Gastrointestinal System Disorders Q 2

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During preparation for bowel surgery, a male client receives an antibiotic to reduce intestinal bacteria. Antibiotic therapy may interfere with the synthesis of which vitamin and may lead to hypoprothrombinemia?

  

    A. Vitamin A

    B. Vitamin D

    C. Vitamin E

    D. Vitamin K

    

    

Correct Answer: D. Vitamin K

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Intestinal bacteria synthesize such nutritional substances as vitamin K, thiamine, riboflavin, vitamin B12, folic acid, biotin, and nicotinic acid. Therefore, antibiotic therapy may interfere with the synthesis of these substances, including vitamin K. Antibiotics, especially those known as cephalosporins, reduce the absorption of vitamin K in the body. Using them for more than 10 days may lower levels of vitamin K because these drugs kill not only harmful bacteria but also the bacteria that make vitamin K.

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Option A: Vitamin A is a general term that encompasses various fat-soluble substances such as retinol, retinyl palmitate, and beta-carotene. In the liver, retinol is esterified to retinyl esters and stored in the stellate cells. In the tissues, both retinol and beta-carotene are oxidized to retinal and retinoic acid, which are essential for vision and gene regulation, respectively. These active metabolites bind nuclear receptors of the RAR family to control gene expression.

Option B: Vitamin D is labeled as the “sunshine vitamin,” as it is produced in the skin on sun exposure. Vitamin D is a hormone obtained through dietary consumption and skin production. Ultraviolet B (UVB) radiation, wavelength (290 to 315 nm) converts 7-dehydrocholesterol in the skin to previtamin D. This previtamin D undergoes heat isomerization and is converted to vitamin D. Vitamin D from the skin and diet is metabolized in the liver to 25-hydroxyvitamin D (25 OH D), and 25-hydroxyvitamin D is useful in assessing vitamin D status.

Option C: Intestinal bacteria don’t synthesize vitamin E. Vitamin E or tocopherol is a fat-soluble vitamin functioning as an antioxidant, protecting the cell membrane. As with all fat-soluble vitamins, transport and absorption require intact fat digestion mechanisms. Fat metabolism involves lipases, both lingual and gastric, bile salts, pancreatic enzymes, and intestinal absorption.

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