March-a, March-a, March-a

Today's topic, Vitamins! Vitamins and what could happen if you overdose or under dose. Vitamins are an important part of our diet. There are several vitamins and two categories they fall into. There are fat soluble vitamins and water soluble vitamins. Vitamins A, D, E, and K are fat soluble. Vitamins B and C are water soluble. Fat soluble vitamins remain in your body for a longer time than water soluble vitamins. Common sense. Water soluble vitamins are excreted through urine. Let's start with the fat soluble vitamins.

Vitamin A (retinol) - The primary functions of Vitamin A is:

-Retinol for reproduction

-Retinoic Acid to support growth and allow for cell maturation/differentiation

-Retinal for vision – night and colour

Foods rich in preformed vitamin A are foods of animal origin such as, liver (the richest source), egg yolk, butter, whole milk. Other foods rich in vitamin A are fruits like watermelon, mango, and apricot; vegetables like carrots, spinach, broccoli, squash, and sweet potatoes.  A good way to tell if a fruit or vegetable is high in vitamin A is to look at its colour. The darker the green or yellow-orange, the higher it will be in vitamin A.

Symptoms of vitamin A deficiency are:

-Night blindness

-Decreased mucus production

Deficiency can lead to bacterial invasion in the eye which can cause irreversible blindness.

Another symptom of vitamin A deficiency is Follicular Hyperkeratosis “goose flesh”.

Supplementation- Beta-carotene supplementation is recommended only to correct vitamin A deficiency and to prevent vitamin A deficiency.

The DRI (Dietary Reference Intake) for Vitamin A is based on 2/3 from animal sources and 1/3 from plant sources.

The RDA (Recommended Daily Allowances) for men is 900 mg RAE and for women, 700 mg (microgram) RAE. However, the RDA increases to 1,300 mg RAE for pregnant and lactating women. The UL (Upper Limit) is 3 mg RAE (3,000 mg RAE).

There is such a thing as overdosing (toxicity) on vitamins. It is FATAL to overdose on vitamin A. Thus why it is a deadly idea to eat polar bear liver.

Vitamin D (cholecalciferol) - The primary function of vitamin D is to regulate blood calcium levels (calcium homeostasis) and regulating cell differentiation and growth. There is research that shows that vitamin D may be protective against colorectal cancer.

There are two different sources of vitamin D. One source is your own skin. Your skin synthesizes vitamin D when it is out in the sunlight. However, if you have sunscreen on, it blocks the ultraviolet light necessary for vitamin D synthesis.  Food sources for vitamin D are foods from animal sources such as fish oils, egg yolk, butter, and liver (richest source in most, if not, all vitamins). There are also fortified food sources like milk and cereal. Read the label on the milk jug or cereal box, it’ll say whether it is fortified with vitamin D.

Symptoms of vitamin D deficiency are osteoporosis, rickets (found in children), osteomalacia (disease found in adults which causes softening of the bones). Elderly people, people living in the northern climate, people with fat malabsorption and vitamin D resistance are at risk for vitamin D deficiency. Those with vitamin D resistance require large doses of calcitriol.

The DRI values for vitamin D (excluding sun exposure) are 5 mg/day for both men and woman (19-50 years old). It increases to 10 mg /day for men and women 50+ years and then 15 mg /day for men and women 70+ years.  The UL for vitamin D is 50 mg/day.

Vitamin D toxicity can lead to hypercalcemia and loss of bone mass.  Most vitamin D overdose is a result of excess supplementation. Signs and symptoms of overdose are an increase in calcium excretion, calcium deposits in kidneys, heart, and blood vessels, and mental retardation.

Vitamin E (a-tocopherol) - Vitamin E has two forms, tocopherol and tocotrienol. It is an antioxidant.

Foods rich in vitamin E are vegetable oils, nuts, liver, leafy green vegetables, and super-fortified cereals. Vitamin E is sensitive to high temperatures, light, and oxygen. Therefore, the longer you cook your food the more vitamin E you lose. Fresh foods (vegetable and fruits) are the best source of vitamins because they have not been cooked.

Deficiency in vitamin E is mostly observed in premature infants, people with low selenium diets, and people with fat malabsorption.  Symptoms of vitamin E deficiency are:

-Neurological disorders

-Hemolytic Anemia

-Retinopathy

The RDA for vitamin E is 15 mg (milligrams)/day for both men and women. However, for pregnant and lactating women it is 19 mg/day. Based on vitamin supplements, the UL is 1,000 mg.

Toxicity of vitamin E inhibits vitamin K metabolism and anticoagulants (substance that prevents blood from clotting), compromises the “balance” of antioxidants, and increases the risk for hemorrhagic damage.

Vitamin K- There are three forms of vitamin K: Phylloquinone (K₁ – found in plants), Menaquinone (K₂ – found in animals), and Menadione (K₃ – found in synthetic sources AKA supplements). The primary functions of vitamin K are Blood clot formation and osteocalcin (calcium-binding properties) activation.

Foods rich in vitamin K are green leafy vegetables and intestinal bacteria. Vitamin K is not sensitive to heat and oxidation.

Vitamin K deficiency can cause prolonged blood coagulation time. Causes of vitamin K deficiency are antibiotics which destroy intestinal bacteria and inhibit vitamin K synthesis and absorption and excess vitamins A and E.  Newborn infants (especially those who are breastfed) can be in risk of vitamin K deficiency because at birth, they lack the intestinal bacteria and they don’t receive much vitamin K through their diet. Thus, infants usually receive an injection of vitamin K at birth.

The RDA for vitamin K is 1 mg/kg body weight. For males it is 120 mg/day and for women it is 90 mg/day. It remains the same for pregnant and lactating women.

It is not likely for toxicity of vitamin K to occur with food source and intestinal bacteria. Toxicity is rare but is most likely to occur with excess supplements. Toxicity can cause hemolytic anemia which has been observed in newborn infants who receive the vitamin K form mendione instead of the recommended form phylloquinone.

Now for the water-soluble vitamins.

Vitamin B- Vitamin B is composed of eight vitamins. The eight vitamins are B₆ and B_12, B₁ (thiamin), B₂ (riboflavin), B₃ (niacin), pantothenic acid, biotin, and folate.  Each vitamin has its own function.

Thiamin (B₁) – A coenzyme in energy metabolism, helps synthesize neurotransmitters, contains sulfur. It is found in whole and enriched grains, pork, legumes, seeds, nuts, and liver.

Deficiency in thiamin (with usually occurs where polished rice is the only staple) can result in Beriberi. Symptoms of beriberi are muscle weakness, loss of appetite, nerve degeneration, and edema (in some cases). Edema is swelling caused by fluid in your body’s tissues. Often occurs in ankles, feet, and legs. Another disease caused by thiamin deficiency is Wernicke-Korsakoff Syndrome. Wernicke-Korsakoff Syndrome is an alcohol- induced malnutrition.

The DRI/RDA for women is 1.1 mg/day and for men it is 1.2 mg/day. Most Americans exceed the RDA in their diet. There is no toxicity because the surplus thiamin is rapidly excreted.

Riboflavin (B₂) – A coenzyme in energy metabolism and supports antioxidants.  It is found in milk and other dairy products, and whole and enriched grains.

Deficiency in riboflavin can result in ariboflavinosis. Symptoms of ariboglavinosis are:

-Glossitis (inflammation and smooth appearance of the tongue)

-Cheilosis (cracked lips at the corners)

-Seborrheic dermatitis (inflammatory skin condition that causes flaky, white to yellowish scales to form on oily areas such as the scalp or inside the ear)

-Stomatitis (inflammation of the mucous lining of any of the structures in the mouth)

-Eye disorder

-Throat disorder

-Nervous system disorder

The DRI/RDA for riboflavin is 1.1 mg/day for women and 1.3 mg/day for men. The average American intake is above the RDA. There has not been any documented toxicity.

Niacin (B₃) - A coenzyme in energy metabolism and supports fatty acid synthesis.  It is found in enriched grains, beef, chicken, turkey, and fish. It is not sensitive to heat so little of the nutrient is lost in cooking.

Deficiency in niacin can result in pellagra and can be prevented with an adequate protein diet.

The DRI/RDA for niacin is 14 mg/day for women and 16 mg/day for men. The UL is >35 mg (more than 35mg). Toxicity of niacin can result in headache, itching, flushing, and liver and GI tract damage.

Pantothenic Acid- It is a component of coenzyme A. It is found in meat, milk, mushrooms, liver, and peanuts.

The DRI is 5 mg/day for both men and women.

Biotin- Primary functions are amino acid metabolism, fatty acid synthesis, and DNA synthesis. It is found in cauliflower, egg yolk, liver, peanuts, and cheese. The human body excretes more biotin than it consumes.

The DRI for biotin is 30 mg/day for adults. There is no toxicity and deficiency is rare.

B₆ (Pyridoxine) – The primary functions are coenzyme in protein and amino acid metabolism, supports immune system and homocystine level. It is found in meat, fish, poultry, liver, potatoes, spinach, avocado, bananas, watermelons, and sunflower seeds. It is sensitive to heat and alkaline.

Vitamin B₆ deficiency can result in Microcytic hypochromic anemia.

The DRI for vitamin B₆ is 1.3 mg/day for all adults. For men over 50 it is 1.7 mg/day and for women over 50 is it 1.5 mg/day. The UL is 100 mg/day. Toxicity of vitamin B₆ can cause permanent nerve damage if it is in high doses and paralysis. Both usually only occur if you take HIGH doses of B₆.

Folate- The primary functions are coenzyme in DNA synthesis and cell division. It is needed for normal red blood cell synthesis. It is found in green leafy vegetables, orange juice, legumes, fortified cereals, and enriched grains.

Deficiency in folate is found in pregnant women and alcoholics. Deficiency in folate can cause megaloblastic anemia.

The DRI/RDA for folate is 400 mg/day for adults. In pregnant women it is 600 mg/day. The UL for folate is 1,000 mg. Toxicity in folate can cause epilepsy, skin disorder, and respiratory disorder. It can also mask pernicious anemia which is a B₁₂ deficiency. The supplement maximum is 400 mg.

Vitamin B₁₂ – The primary functions are it is needed for normal folate function, DNA and red blood cell synthesis, and maintains myelin sheath around nerves. It is stored in the liver. It is found only in animal sources: meats, liver, milk, eggs.

Deficiency in B₁₂ can cause Pernicious anemia. Symptoms of pernicious anemia are:

-Nerve degeneration, weakness

-Tingling/numbness in the extremities

-Paralysis and death

-Looks like folate deficiency

It is usually due to decreased absorption ability.

 The DRI/RDA for vitamin B₁₂ is 2.4 mg/day for adults and elderly adults. B₁₂ is non-toxic.

Vitamin C- The primary functions are it is needed for collagen synthesis and it is an antioxidant.

Foods rich in vitamin C are citrus fruits, potato, green pepper, cauliflower, broccoli, strawberry, romaine lettuce, and spinach.

Vitamin C deficiency can result in scurvy. Scurvy occurs when one has been vitamin C deficient for 20- 40 days (less than 10mg/day). Symptoms are fatigue, and pin point hemorrhages. It occurred a lot with sailors. When it was discovered what was causing scurvy the British navy made sure each ship had a large supply of limes (citrus fruit) hence the name, Limeys. Another disease is Rebound Scurvy. Rebound Scurvy occurs when one immediately stops taking excess vitamin C supplements.

The DRI/RDA for vitamin C is 90 mg/day for men, 75 mg/day for women and +35 to each RDA for smokers. The UL is 2 g/day (2,000 mg/day).

Interesting, right?

Cheers,

-Claire