fat-soluble vitamins

• Vitamin A is important for vision, growth, development, immune function, reproduction, and cell differentiation.
• Retinol (preformed) and carotenoids are the two forms of Vitamin A found in food sources.
• Preformed Vitamin A can be obtained from animal products such as liver, eggs, dairy, and fortified foods like cereals or margarine.
• Carotenoid precursors to Vitamin A include beta-carotene, alpha-carotene, gamma-carotene, lycopene, lutein/zeaxanthin, and cryptoxanthin.
• The conversion rate of beta-carotene to Vitamin A varies depending on factors such as age, genetics, dietary status, and health conditions.
• Factors that affect the absorption of Vitamin A include the presence of fats, bile salts, pancreatic enzymes, and intestinal mucosa.
• Age affects the efficiency of converting beta-carotene to Vitamin A, with infants having higher rates than adults.
• Deficiency of Vitamin A leads to night blindness, keratinization of epithelial cells, xerophthalmia, and increased susceptibility to infection.
• Excessive consumption of Vitamin A can lead to toxicity symptoms such as nausea, vomiting, headache, hair loss, skin peeling, and birth defects.
• Vitamin D plays an essential role in calcium homeostasis by promoting its absorption in the small intestines and inhibiting its excretion through urination.
• Vitamin D is synthesized from cholesterol in the skin when exposed to sunlight or obtained from food sources like fish liver oils, egg yolk, and fortified foods.
• Vitamin D deficiency can cause rickets (softening of bones) in children and osteomalacia (softening of bones) in adults.
• Vitamin K is involved in blood clotting and bone metabolism.
• Vitamin E acts as an antioxidant and protects cell membranes from oxidative damage caused by free radicals.
• The two forms of Vitamin D are ergocalciferol (D2) found in plants and cholecalciferol (D3) produced in the body upon exposure to UV light.
• Vitamin K is involved in blood clotting and bone metabolism, with phylloquinone (K1) derived from green leafy vegetables and menaquinones (K2) produced by bacteria in the gut.
• Vitamin E deficiency can result in neurological problems, muscle weakness, and hemorrhage.
• Symptoms of Vitamin E deficiency include muscle weakness, ataxia, retinopathy, and hemolytic anemia.
• The recommended daily allowance (RDA) for Vitamin E varies based on age and gender.
• Retinoids are derivatives of retinaldehyde that act as hormones and play roles in embryonic development, differentiation, and proliferation.
• Fat-soluble vitamins include A, D, E, and K.
• Deficiencies of Vitamin A, D, E, and K are rare due to their storage in adipose tissue and liver.
• Toxicity symptoms of Vitamin E overdose may include nausea, diarrhea, headache, dizziness, blurred vision, and increased bleeding time.
• Toxicity symptoms of Vitamin D include hypercalcemia, kidney stones, calcification of soft tissues, and increased risk of fractures.
• Sources of Vitamin E include vegetable oils, nuts, seeds, whole grains, and fortified cereals.
• Excessive intake of Vitamin A can lead to toxicity symptoms such as headache, nausea, vomiting, dizziness, blurred vision, hair loss, skin rash, and joint pain.
• Carotenoids are pigments responsible for yellow/orange coloring in fruits and vegetables, including carrots, sweet potatoes, pumpkins, cantaloupes, mangoes, apricots, peaches, papayas, and tomatoes.
• Vitamin K toxicity is not common but can occur with high doses.