Niacin: Vitamin B3, Nicotinamide, Nicotinic Acid Niacin, or vitamin B3,

 is involved in energy production, normal enzyme function, digestion, promoting normal appetite, healthy skin, and nerves.

RDA Males: 16 mg/day; Females: 14 mg/day

Niacin Deficiency : Pellagra is the disease state that occurs as a result of severe niacin deficiency. Symptoms include cramps, nausea, mental confusion, and skin problems.

FLUORIDE

The safe limit of fluorine is about 1PPM in water. But excess of fluoride causes Flourosis

Flourosis is more dangerous than caries. When Fluoride content is more than 2 PPM, it will cause chronic intestinal upset, gastroenteritis, loss of weight, osteosclerosis, stratification and discoloration of teeth

CLASSIFICATION OF LIPIDS

Lipids are classified as follows:

1. Simple lipids: Esters of fatty acids with various alcohols.

(a) Fats: Esters of fatty acids with glycerol. Oils are fats in the liquid state. A long-chain carboxylic acid; those in animal fats and vegetable oils often have 12–22 carbon atoms.

(b) Waxes: Esters of fatty acids with higher molecular weight monohydric alcohols. Waxes are carboxylic acid esters, RCOOR’ ,with long, straight hydrocarbon chains in both R groups

2. Complex lipids: Esters of fatty acids containing groups in addition to an alcohol and a fatty acid.

(a) Phospholipids: Lipids containing, in addition to fatty acids and an alcohol, a phosphoric acid residue. They frequently have nitrogen containing bases and other substituents,

Eg  glycerophospholipids the alcohol is glycerol

     sphingophospholipids the alcohol is sphingosine.

(b) Glycolipids (glycosphingolipids): Lipids containing a fatty acid, sphingosine, and carbohydrate. These lipids contain a fatty acid, carbohydrate and nitrogenous base. The alcohol  is sphingosine, hence they are also called as glycosphingolipids. Clycerol  and phosphate  are absent  

e.g., cerebrosides, gangliosides.

(c) Other complex lipids: Lipids such as sulfolipids and aminolipids. Lipoproteins may also be placed in this category.

3. Precursor and derived lipids: These include fatty acids, glycerol, steroids, other alcohols, fatty aldehydes, and ketone bodies, hydrocarbons, lipid soluble vitamins, and hormones. Because they are uncharged, acylglycerols (glycerides), cholesterol, and cholesteryl esters are termed neutral lipids

4. Miscellaneous lipids: These include a large number of compounds possessing the characteristics of lipids e.g., carotenoids, squalene, hydrocarbons such as pentacosane (in bees wax), terpenes etc.

NEUTRAL LIPIDS: The lipids which are uncharged are referred to as neutral lipids. These are mono-, di-, and triacylglycerols, cholesterol and cholesteryl esters.

Riboflavin: Vitamin B2

Riboflavin, or vitamin B2, helps to release energy from foods, promotes good vision, and healthy skin. It also helps to convert the amino acid tryptophan (which makes up protein) into niacin.

RDA Males: 1.3 mg/day; Females: 1.1 mg/day

Deficiency : Symptoms of deficiency include cracks at the corners of the mouth, dermatitis on nose and lips, light sensitivity, cataracts, and a sore, red tongue.

Erythrocytes and the Pentose Phosphate Pathway

The predominant pathways of carbohydrate metabolism in the red blood cell (RBC) are glycolysis, the PPP and 2,3-bisphosphoglycerate (2,3-BPG) metabolism (refer to discussion of hemoglobin for review of the synthesis and role role of 2,3-BPG).

Glycolysis provides ATP for membrane ion pumps and NADH for re-oxidation of methemoglobin. The PPP supplies the RBC with NADPH to maintain the reduced state of glutathione.

The inability to maintain reduced glutathione in RBCs leads to increased accumulation of peroxides, predominantly H₂O₂, that in turn results in a weakening of the cell wall and concomitant hemolysis.

Accumulation of H₂O₂ also leads to increased rates of oxidation of hemoglobin to methemoglobin that also weakens the cell wall.

Glutathione removes peroxides via the action of glutathione peroxidase.

The PPP in erythrocytes is essentially the only pathway for these cells to produce NADPH.

Any defect in the production of NADPH could, therefore, have profound effects on erythrocyte survival.

These are normally non-essential but become essential during stress, illness, or in infants.