Chapter 8 THE WATER- SOLUBLE VITAMINS

Vitamin Talk Vitamins are organic compounds essential in the diet to promote growth and health maintenance. Water-soluble vitamins include the B vitamins and vitamin C. Fat-soluble vitamins include A, D, E and K. B vitamins were originally thought to be one chemical substance but are actually many different substances. That is the reason for B 1, B 2, B 12, etc. Copyright 2012, John Wiley & Sons Canada, Ltd.

The Vitamins Copyright 2012, John Wiley & Sons Canada, Ltd.

Finding Vitamins in Foods Copyright 2012, John Wiley & Sons Canada, Ltd.

Fortified and Enriched Foods Fortification: process of adding nutrients to foods. The added nutrients are generally not found in the food, such as fortifying orange juice with calcium. Enrichment: adding nutrients back to foods that have lost nutrients due to processing. An example is the addition of B vitamins to white rice. Copyright 2012, John Wiley & Sons Canada, Ltd.

Fortification Health Canada regulates which foods must be fortified and which nutrients should be added. Example:  table salt with iodine  milk with Vitamin D  grains with thiamine, riboflavin, niacin, iron and folic acid Copyright 2012, John Wiley & Sons Canada, Ltd.

Dietary Supplements Dietary supplements can be another source of vitamins in the modern diet. Dietary supplements contain some combination of vitamins, minerals, herbs, botanicals, amino acids, enzymes or extracts. Dietary supplements cannot replace the benefits of a diet containing a wide variety of foods. Dietary supplements are regulated by Health Canada’s Natural Health Products Directorate. Copyright 2012, John Wiley & Sons Canada, Ltd.

Dietary Supplements (continued) There is a concern that natural health products in food format may confuse the consumer. Dietitians of Canada is concerned that the consumer may perceive these products as food, be unaware that there are maximum doses and exceed the ULs for some nutrients, with potential adverse effects, as there are no nutritional facts on these products’ labels. Copyright 2012, John Wiley & Sons Canada, Ltd.

Absorption of Vitamins Copyright 2012, John Wiley & Sons Canada, Ltd.

Bioavailability of Vitamins Vitamins must be absorbed by the body in order to perform their functions. Approximately 40-90% of vitamins are absorbed in the small intestine. Fat-soluble vitamins require fat in the diet to be absorbed. Water-soluble vitamins may require transport molecules or specific molecules in the GI tract. Some vitamins are absorbed in inactive provitamin or vitamin precursor forms that must be converted into active forms by the body. Copyright 2012, John Wiley & Sons Canada, Ltd.

Thiamin Thiamin was the first B vitamin to be identified and is also called B 1. Thiamin is widely available in foods, especially in enriched grains, whole grains, legumes, nuts and seeds. Thiamin assists in energy production, carbohydrate metabolism, the production of ribose and the health of the nervous system. Copyright 2012, John Wiley & Sons Canada, Ltd.

Thiamin Copyright 2012, John Wiley & Sons Canada, Ltd.

Riboflavin Dairy products are a good source of riboflavin. Plant sources of riboflavin include mushrooms, broccoli, asparagus, whole grains and green, leafy vegetables. Animal sources include red meat, poultry and fish. Riboflavin is easily destroyed by heat and exposure to light. Riboflavin is an important component in the citric acid cycle and for assisting the body with the absorption of other vitamins. Copyright 2012, John Wiley & Sons Canada, Ltd.

Riboflavin Copyright 2012, John Wiley & Sons Canada, Ltd.

Niacin Niacin is added to enriched flours in North America. A niacin deficiency disease is pellagra. Niacin can be synthesized in the body from the essential amino acid tryptophan if the diet is adequate in tryptophan. Niacin plays an important role in the production of energy and in general metabolism. Two forms of niacin are nicotinic acid and nicotinamide. Copyright 2012, John Wiley & Sons Canada, Ltd.

Niacin Copyright 2012, John Wiley & Sons Canada, Ltd.

Niacin Advanced pellagra’s symptoms include the 3 D’s: dermatitis, diarrhea and dementia. Niacin toxicity from overuse of niacin supplements can result in elevated blood pressure, cardiac arrhythmia, nausea, vomiting, elevated blood sugar levels and impaired liver function. Copyright 2012, John Wiley & Sons Canada, Ltd.

Pantothenic Acid Copyright 2012, John Wiley & Sons Canada, Ltd.

Vitamin B 6 Copyright 2012, John Wiley & Sons Canada, Ltd.

Vitamin B 6 Vitamin B 6 is also called pyridoxine and comprises a group of compounds including pyridoxal, pyridoxine, and pyridoxamine. All three forms can be converted into pyridoxal phosphate, which is required for many enzyme reactions in the body. Vitamin B 6 deficiency may result in anemia due to impaired hemoglobin synthesis and neurotransmitter issues. Copyright 2012, John Wiley & Sons Canada, Ltd.

Folate or Folic Acid Copyright 2012, John Wiley & Sons Canada, Ltd.

Folate or Folic Acid Folate coenzymes are needed for DNA synthesis and the metabolism of some amino acids. Low folate intake in early pregnancy is associated with an increased risk of neural tube defects. Low folate intake has been associated with an increased risk of heart disease related to the metabolism of the amino acid homocysteine. Copyright 2012, John Wiley & Sons Canada, Ltd.

Folate Deficiency and Neural Tube Defects Copyright 2012, John Wiley & Sons Canada, Ltd.

Folate Fortification Neural tube defects have decreased by 50% in Canada since food fortification. Newfoundland rates have dropped by 80%. Alberta and Quebec have found a reduction in the number of congenital heart defects. Ontario reported a reduction in neuroblastoma. Copyright 2012, John Wiley & Sons Canada, Ltd.

Folate Fortification Some studies have shown an increase in colon cancer since folate fortification began in This maybe the result of folate stimulating DNA synthesis and promoting growth of pre- existing cancerous cells. When considering food fortification it is important to consider that what may benefit one segment of the population may harm another segment. Copyright 2012, John Wiley & Sons Canada, Ltd.

Macrocytic Anemia and Folate Deficiency Copyright 2012, John Wiley & Sons Canada, Ltd.

Calculating Dietary Folate Amounts Copyright 2012, John Wiley & Sons Canada, Ltd.

Vitamin B 12 Copyright 2012, John Wiley & Sons Canada, Ltd.

Vitamin B 12 Pernicious anemia is a form of anemia that does not respond to iron supplementation. Vitamin B 12 is necessary for the proper absorption of iron in the body. Excessive intake of folic acid can mask B 12 deficiencies. Vitamin B 12 is most readily absorbed from animal products. Vegan diets need to be supplemented with readily- absorbable forms of B 12. Atrophic gastritis may lead to B 12 deficiencies. Copyright 2012, John Wiley & Sons Canada, Ltd.

Absorption of Vitamin B 12 Copyright 2012, John Wiley & Sons Canada, Ltd.

Vitamin C Copyright 2012, John Wiley & Sons Canada, Ltd.

Vitamin C Vitamin C is also known as ascorbic acid or ascorbate. Vitamin C in foods can be destroyed by oxygen, light and heat, as well as contact with copper or iron cookware. Vitamin C functions as an antioxidant in the body, helps maintain the immune system, is important in the production of collagen and aids in iron absorption. Copyright 2012, John Wiley & Sons Canada, Ltd.

How Antioxidants Work Copyright 2012, John Wiley & Sons Canada, Ltd.

Summary of Water-Soluble Vitamins and Choline Copyright 2012, John Wiley & Sons Canada, Ltd.

Summary of Water-Soluble Vitamins and Choline (continued) Copyright 2012, John Wiley & Sons Canada, Ltd.

Summary of Water-Soluble Vitamins and Choline (continued) Copyright 2012, John Wiley & Sons Canada, Ltd.

Benefits and Risks of Water-Soluble Vitamin Supplements Copyright 2012, John Wiley & Sons Canada, Ltd.

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