Water Soluble Vitamins!!! YES
What are general characteristics of water-soluble vitamins vs. fat-soluble vitamins?
General Characteristics of Vitamins
• Small, organic compounds (contain carbon).
• Needed in small amounts (micrograms or milligrams).
• Usually obtained from food.
• Some are synthesized by the body.
o Vitamin D is made in skin from exposure to sunlight (UVB rays).
o Vitamin K is made by bacteria in GI tract.
• May be a precursor or provitamin.
o Example: Beta carotene is converted by the body into vitamin A.
• There are more than 1 form of some vitamins. Example: menaquinone and phylloquinone
are both active forms of vitamin K.
• Essential to life.
• Each has one or more specific functions.
• Regulate body processes; support growth.
• Do not provide energy (kcalories).
• Some are toxic in high doses (such as from megadoses from supplements).
o Examples: Vitamins A & D
• No perfect food contains all vitamins.
• Body can’t detect difference between synthetic and natural vitamins.
• Classified as fat soluble or water soluble
Absorption:
Water-soluble vitamins are absorbed from the GI tract directly into the bloodstream.
Fat soluble vitamins are absorbed with lipids into the lymph system before entering the bloodstream.
Excretion:
Excess water-soluble vitamins (or their metabolites) are excreted in the urine.
Fat soluble vitamins cannot be excreted in the urine, so excess amounts are stored in the body.
Storage:
Water-soluble vitamins are found in water in cells and fluids. They are not stored in large amounts (with the exception of vitamin B12).
Fat soluble vitamins are stored in the liver and fatty tissues.
Toxicity:
Fat Soluble vitamins can be toxic in high doses. This is especially true for vitamins A and D.
Some water-soluble vitamins can be also be toxic in very high amounts from supplements. Since excess fat-soluble vitamins can’t be excreted, there is a greater risk of toxicity from high doses of fat-soluble vitamins than from high doses of water-soluble vitamins.
Transport:
Water-soluble vitamins travel freely in the body and don’t require transport protein in the bloodstream.
Fat-soluble vitamins require transport proteins to travel in the bloodstream.
Thiamin
Thiamin ( B1)
Functions:
• Coenzyme in energy metabolism; essential in carbohydrate energy metabolism as part of the co-enzyme Thiamin Pyrophosphate (TPP)
• Essential for healthy nerve function
RDA:
• Women – 1.1 mg/day
• Men – 1.2 mg/day
Deficiency:
• Called Beriberi
• Symptoms include nerve damage, poor coordination, paralysis, loss of appetite, mental depression, and heart failure. Beriberi may be wet (with edema) or dry (no edema).
• Causes Wernicke-Korsakoff Syndrome in alcoholics.
Toxicity: No
Food Sources: Enriched grains, pork, fish, and legumes are good sources. There are small to moderate amounts in many foods, including whole grains, meats, and nuts.
Riboflavin
Riboflavin (B2)
Functions:
• Coenzyme in energy metabolism (FAD)
• Essential for DNA synthesis
• Needed for healthy skin and vision.
• Converts the amino acid tryptophan to niacin.
o Part of the coenzymes flavin monoucleotide (FMN) and flavin adenine dinucleotide
RDA:
• Women - 1.1 mg/day
• Men - 1.3 mg/day
Deficiency:
• Called Ariboflavinosis
• Symptoms include cheilosis (dry, red, cracked corners of mouth); glossitis (smooth red tongue); skin rash; eyes sensitive to light
Toxicity: No
Food Sources:
• Dairy is high in riboflavin and is the best riboflavin source for most Americans who consume dairy products.
• Meat, dark green vegetables, whole grains and enriched grains, mushrooms, and liver are additional good sources.
Niacin (B3)
Function:
• Coenzyme in many metabolic reactions (glucose, fat, & alcohol)
o Part of NAD (nicotinamide adenine dinucleotide)
o Part of NADP (nicotinamide adenine dinucleotide phosphate).
• Supports skin, nervous, and digestive systems.
Unique Property: The body synthesizes niacin from the essential amino acid tryptophan.
• 1 mg niacin = 60 mg dietary tryptophan
RDA:
• Women - 14 mg/day
• Men - 16 mg/day
Deficiency: Pellagra
• Causes the 4 “Ds” - diarrhea; dermatitis; dementia; death
Toxicity: Yes, especially nicotinic acid (from very high doses from supplements).
• Niacin flush; liver damage; impaired glucose tolerance ( blood sugar)
Food Sources: Meat, liver, poultry, seafood, and legumes; peanuts; whole grains, enriched grains;mushrooms, potatoes.
B12
Cobalamin – Vitamin B12
Functions:
• DNA & RNA synthesis; new cell formation (notice folate also has this function)
o red blood cell formation
o growth
• Myelin synthesis – essential for normal nerve function
Absorption:
• HCL produced by stomach releases B12 from foods.
• B12 absorption in the small intestine requires Intrinsic Factor, a protein made by the stomach.
RDA: 2.4 ug/day for women and men
Deficiency:
• Cognitive impairment (an early symptom)
• Pernicious anemia (from lack of intrinsic factor)
• Macrocytic or megaloblastic anemia (large immature red blood cells)
• Permanent nerve damage; paralysis.
Risk Factors for B12 Deficiency: vegan diet*
, long-term use of heartburn medications, older
adults (50+ years), diabetic on Metformin, major stomach disease/surgery (i.e., bariatric surgery)
*Vegans should eat foods fortified with vitamin B12 or take a B12 supplement to avoid B12 deficiency.
Toxicity: No
Food Sources: Animal products and B-12 fortified foods and beverages only. Meat, poultry, seafood, eggs, and dairy products are good sources.
B6
Pyridoxine, Pyridoxal, Pyridoxamine (3 forms)
Functions:
• Coenzyme in energy metabolism reactions; needed for amino acid and fatty acid metabolism and for protein synthesis
o Part of the coenzyme pyridoxamine phosphate (PMP)
o Part of the coenzyme pyridoxal phosphate (PLP)
• Essential for hemoglobin formation in red blood cells.
RDA: 1.3 mg - adults
UL: 100 mg daily for adults
Deficiency: microcytic hypochromic anemia (anemia with small red blood cells low in hemoglobin);
weakness, fatigue, growth failure, impaired motor function, convulsions, depression.
Toxic: Yes (from very high doses from supplements). Causes irreversible nerve damage. To avoid
toxicity, stay under the UL.
Food Sources: Widely distributed in foods. Good sources include chicken, meat, legumes, green leafy vegetables, potatoes, whole grains, bananas, watermelon.
Vitamin C
Ascorbic Acid – Vitamin C
Functions:
• collagen synthesis
• aids in wound healing (scar tissue is collagen)
• antioxidant
• supports immune function
• promotes absorption of non-heme iron (such as the iron from legumes, vegetables, nuts, seeds, and grains)
Note: Vitamin C does not prevent the common cold.
RDA:
75 mg/day - women
90 mg/day - men
+35 mg/day - smokers
UL: 2,000 mg/day
Deficiency:
• Called Scurvy
• Symptoms: bleeding gums, pinpoint hemorrhages, swollen painful joints, delayed wound healing, sudden death from massive internal bleeding (these are symptoms of inability to make collagen)
Toxicity: Nausea, vomiting, diarrhea, kidney stones, flare-up of gout in those who have gout
Sources: Fruits and vegetables. Many fruits and vegetables are good sources of vitamin C. A good strategy to meet your vitamin C needs is to eat your recommended servings of fruits and vegetables.
Folate
Folate and Folic Acid (B9)
Functions:
• DNA & RNA synthesis; cell division - new cell formation (notice B12 also has this function).
o red blood cell formation
o growth
• Activates B12
• Coenzyme forms are THF (tetrahydrofolate) & DHF (dihydrofolate)
RDA:
400 ug/day - women*
600 ug/day - men
600 ug/day - pregnancy
*It is important for women of childbearing age to consume the RDA for folate in case a pregnancy occurs, to prevent neural tube defects (such as Spina Bifida or anencephaly) in the fetus.
UL: 1,000 ug/day
Deficiency:
• Macrocytic or megaloblastic anemia (large immature red blood cells)
• Mental confusion, depression, GI deterioration.
• Neural tube defects such as Spina Bifida in the fetus can occur when the mother has folate deficiency early in pregnancy.
Toxicity: Masks early symptoms of vitamin B12 deficiency.
Food Sources: Fortified grains since 1996, green leafy vegetables, legumes, liver, asparagus, citrus fruits