Vitamins - Chapter 7 Flashcards
The Basics of Vitamins
- Essential, non-caloric organic nutrients
- Needed in very small amounts
- Cofactors (helpers) in cell functions
NOTE: you do not need to memorize the RDA, AI, or
TUL amounts
Classification of Vitamins
- Fat Soluble
- Water Soluble
Fat soluble: vitamins A, D, E, K
- Dissolve in lipid
- Require bile for absorption
- Transported in lymph
- Stored in tissues (e.g., liver, adipose)
- May be toxic in excess
- Caution with supplements
Precursor (Vitamin A)
β-carotene (can be converted to vitamin A but need 6x amount
Essential For (Vitamin A)
- Gene expression
- Vision
- Epithelial tissue
- Immune defenses
- Growth of bone
- Reproduction
Beta-Carotene (Vitamin A)
- Vitamin A precursor
- Plant sources: brightly coloured, e.g., deep orange, dark green
- Effective antioxidant
- May reduce risk of chronic diseases
- Eye diseases (e.g., macular degeneration), cancer
Toxicity symptoms (Vitamin A)
- UL = 3000ug/d
- Stunted growth, muscle/bone soreness, headaches
- Edema, fatigue, blurred vision
- Anorexia, nausea, diarrhea
- Skin disorders, rashes, itching
- Liver damage, enlargement of spleen
Beta Carotene Toxicity (Vitamin A)
Yellowing of the skin
Other Forms of Vitamin A
- Retinoic acid as a drug, directly applied to the skin results in rapid turnover of skin cells
- Retin-A:
- Acne; Renova: anti-wrinkle
- Highly toxic:
- Serious birth defects if taken during pregnancy
- Supplementing vitamin A does not help acne
Sunlight (Vitamin D)
- UV radiation converts precursor molecule (cholesterol backbone) in skin
- Duration specific to skin color: facial area for 15 min 3-7 x/week → 3 h for dark-skinned
- Manitoba latitude: April to Oct.; use liver stores in winter
- Sunscreen prevents skin exposure to UV
Sunlight (Vitamin D - Part 2)
- Time of day: midday hours provide maximum direct sun
exposure - Lifestyle: work indoors, homebound
- Risk of skin cancer, not vitamin D toxicity with ++
Deficiency Can Lead To (Vitamin D)
- Rickets:
- Bone disease in children
- Osteomalacia:
- Bone disease in adults
Research (vitamin D)
-Vitamin D deficiency may increase risk of high blood pressure, some cancers, type 1 diabetes, heart disease, rheumatoid arthritis,
inflammatory bowel disease, multiple sclerosis
- Risk of deficiency increases with age
Widespread in Foods (Vitamin E)
- Vegetable oils
- F&V
- Fortified cereals and grains
- Meats and meat alternatives
- Milk products
- Destroyed by heat processing
Deficiency (Vitamin E)
- Deficiency is rare (widespread in foods, body stores ++, cells recycle)
- Erythrocyte hemolysis in premature infants born before 30 weeks
- Weakness, impaired reflexes (muscle and nerve function) oxidative
damage - Caused by fat absorption and storage problems
Toxicity (Vitamin E)
- Upper Limit: 1,000 mg/d
- Toxicity is rare
- Nausea, fatigue, GI distress, blurred vision
- ↑ risk bleeding when combined with anticoagulant medications
- > 400 IU/day: ↑ risk death from all causes
Sources (Vitamin K)
- Bacterial production in colon
- Affected by absorption problems/illness
- Antibiotics decrease production
Deficiency Rare (Vitamin K)
- Newborns need supplements due to sterile GI tract
- Taking meds that kill intestinal bacteria (good and bad)
- Problems with fat absorption
- Symptoms: easy bruising, hemorrhaging
Toxic in Excess (Vitamin K)
- In infants or during pregnancy: taking vitamin K supplement
- Symptom: jaundice RBC’s break and release pigment (bilirubin)
Water Soluble Vitamins
- Vitamins C, B vitamins
- Dissolve in water
- Are easily absorbed and excreted
- Are not stored extensively in tissues
- Seldom toxic levels
Toxicity Risk (Vitamin C)
- Problems if >2 g/day; e.g., altered insulin response to carbohydrate, GI upset
- Can interfere with anticoagulation meds
Hemochromatosis (too much iron) should avoid vitamin C supplements
The B Vitamins
- Act as coenzymes
- Involved in energy metabolism
- Be familiar with name and number:
- Thiamin (B1)
- Riboflavin (B2)
- Niacin (B3)
- Pantothenic acid (B5)
- Pyridoxine (B6)
- Biotin (B7)
- Folate (B9)
- Cobalamin (B12)
Thiamin B1
- Alcohol impairs thiamin absorption and speeds up thiamin excretion
- Wernicke-Korsakoff syndrome: apathy, irritability, mental confusion,
disorientation, memory loss
- Wernicke-Korsakoff syndrome: apathy, irritability, mental confusion,
- Toxicity symptoms:
- none reported
Toxicity (Niacin B3)
- Flushing of skin, red skin rash
- Tingling sensation in hands/feet
- Stomach pain, nausea, diarrhea
- Body adapts to high doses, but monitor for liver damage
Niacin as a drug?
- Niacin may be used as part of treatment to lower blood cholesterol levels
- Self dosing not advised liver damage, peptic ulcers, vision loss as result of large doses
At Risk of Deficiency (Folate B9)
- Pregnant individuals
- Older adults (many medications interact with folate absorption)
- Alcoholics (decreased folate absorption)
- Smokers (folate inactivation in lungs)
Low folate status may contribute to (Folate B9)
- Hyperhomocysteinemia, a risk factor for cardiovascular disease
- ↑ risk cancer (colon, cervical)
Toxicity
Can mask vitamin B12 deficiency (resolves anemia)
Cobalamin B12
- Folate and B12 depend on one another for activation
- Both cause identical anemia with deficiency
Intrinsic Factor (Cobalamin B12)
- Need intrinsic factor (IF) for B12 absorption
- B12 binds intrinsic factor (IF) in stomach and facilitates absorption in small intestine
- Decreased IF and B12 absorption in elderly
- If no IF
- Injections of B12 or oral supplement
Risk of Deficiency (Cobalamin B12)
Breastfed infants of vegan mothers (adults have body stores for 6 years)
Toxicity from Supplements (Pyridoxine B6)
- Symptoms:
- Numbness due to nerve damage
- Reversed when quit
supplements
Supplement use (Pyridoxine B6)
- Some take for carpal tunnel syndrome / sleep disorders research showing ineffective
- Relieving PMS research showing ineffective
Controversy 7: Vitamin Supplements (1 - Who Benefits?)
- Those who routinely fail to obtain recommended amounts of vitamins and
minerals from the diet - Those with special needs (e.g., pregnant, older adults)
- Some valid reasons for taking supplements
- Research conflicting
- Some experts believe all healthy people may benefit from daily multivitamin supplement
Controversy 7: Vitamin Supplements (2 - Regulation of Supplements)
- Natural Health Products (NHPs):
- Vitamins and minerals
- Herbal remedies
- Homeopathic medicines
- Chinese traditional medicines
- Probiotics
- AAs and EFAs
- Must be safe for over-the-counter, not require a prescription, and be available
for self-care and self selection
Controversy 7: Vitamin Supplements (3 - Approved Products have)
- Natural Product Number
(NPN) or - Drug Identification Number
– Homeopathic Medicine
(DIN-HM)
Controversy 7: Vitamin Supplements (4 - Research on Supplementation - Unconvincing outcome)
Thought was that supplementation of vitamin E
may provide additional antioxidant protection and decrease chronic disease risk (e.g., heart disease) – research not supporting
Controversy 7: Vitamin Supplements (4 - Research on Supplementation -Negative outcomes)
- Supplementation of β-carotene increased incidence of lung cancer in smokers
- Vitamin A supplements:
- Bone health (↑ vit A linked with ↑ risk hip fractures)
- Liver injury at high doses (>10,000 ug/d)
Controversy 7: Vitamin Supplements(5 - Reasons to think twice before taking)
- Greater risk toxicity
- Expensive
- May give false sense of security
- Some invalid reasons
for taking supplements
Controversy 7: Vitamin Supplements (6 - Conclusion)
Try to make changes to
diet to improve nutritional content and only take supplements when
truly needed
