Vitamins: Essential Nutrients for Health
Starting Solid Foods and Vitamins
Phase III: Introducing Solid Foods
Introduce foods like yogurt, toast, boiled potatoes, pasta, soup, ham, boiled apple or pear, quince, and boiled carrots.
Phase IV: Transitioning to a Regular Diet
Continue with an easily digestible diet, including:
- Soft broth soup with pasta
- Boiled ham (lean)
- Boiled potatoes
- Boiled apple or quince
As tolerance improves, gradually add:
- Veal steak
- Chicken
- Grilled white fish
- Bananas and pears
- Mashed vegetables
Avoid cow’s milk until full recovery.
Understanding Vitamins
Vitamins: Vita (Life), Amin (containing nitrogen compound). Vitamins are essential organic compounds that act as catalysts or coenzymes in chemical reactions to maintain normal metabolic function, growth, and tissue repair. They do not provide energy, and the daily intake requirement is small.
Classification of Vitamins
- Water-Soluble: Absorbed in the gastrointestinal tract (GIT). Renally excreted, making accumulation less likely. Examples include ascorbic acid (vitamin C), B complex vitamins (except vitamin B12, which requires intrinsic factor), biotin, and pantothenic acid.
- Fat-Soluble: Bind to fats for absorption and are stored in the liver and fatty tissue. They can reach toxic levels. Examples include vitamins A, D, and K.
Digestion and Absorption of Water-Soluble Vitamins
Occurs in the small intestine. Absorption at physiological doses is primarily active and sodium-dependent (saturable). Pharmacological doses are absorbed passively (non-saturable). Passive transport can be beneficial when active transport is limited due to illness (e.g., vitamin B12 in the elderly).
Transport, Storage, and Excretion of Water-Soluble Vitamins
In the blood, they are transported in free form, bound to albumin, erythrocytes, and leukocytes, except for cobalamin (B12), which uses transcobalamin. The main storage tissues are the liver, kidney, muscle, and brain, except for cobalamin, which is primarily stored in the liver. Reserve capacity lasts for days to months, except for cobalamin, where deficiency takes 2-4 years to manifest. Renal excretion occurs (except for folic acid and B12).
Digestion and Absorption of Fat-Soluble Vitamins
Absorption occurs in the small intestine and requires dietary fat. Vitamins are bound to esters that need to be hydrolyzed. Micellar fat-soluble vitamins are passively absorbed into mucosal cells. Any condition causing poor digestion or absorption of fat can lead to fat-soluble vitamin deficiency. Excretion occurs via bile and feces. The liver is the main storage site.
Vitamin A
Includes retinol and its precursors. Essential for vision, reproduction, immune function, maintaining mucus-secreting epithelial cells, and bone growth. It also acts as an antioxidant. Sources include milk, eggs, liver, and green and yellow vegetables and fruits. Deficiency can cause night blindness and dryness of the conjunctiva. Toxicity symptoms include gastrointestinal issues, papilledema, and hypercalcemia.
Vitamin D
Also known as calciferol. Maintains calcium and phosphorus levels necessary for calcification and neuromuscular activity, in conjunction with PTH and calcitonin. It also enhances immune function. Sources include ultraviolet light, fish oil, milk, and eggs, facilitated by bile salts. Deficiency can lead to rickets, osteomalacia, and osteoporosis. Toxicity symptoms include hypercalcemia, hyperphosphatemia, and gastrointestinal issues.
Vitamin E
A component of all cell membranes, acting as a lipid antioxidant by reacting with free radicals to convert them into less toxic forms. It slows the development of atherosclerosis and reduces the severity of retinopathy and intracranial hemorrhage in preterm infants. Sources include oils, margarine, wheat germ, and whole grains.