Fluorine is a negatively charged ion and is generally known as fluoride. Fluoride is a part of the
natural environment and is found in natural water bodies. The concentration of fluoride varies
from one region to another. Sea water contains about 1.2-1.5 ppm of fluoride and fresh water
fluoride concentrations are usually lower, that is about 0.01 to 0.3 ppm. Fluoride salt is
routinely added to tooth paste to prevent dental caries.

Sources of fluoride in the diet
Fluoride is found in meat, fish, and cereals. It is found in higher concentrations in canned foods,
ground chicken meat products, chocolate milk and some baby dietary supplements. Fluoride
concentration depends on the ingredients used in the preparation of foods. (1, 5).
Most foods are poor sources of fluoride. This is the reason why fluoride is added to drinking
water which is called fluoridation. The most important source of fluoride is fluoridated water.
According to WHO Guidelines for Drinking-water Quality, the optimal value of fluoride in
drinking water is 1.5 mg l –1 .

How much fluoride do we need?
The recommended dietary allowance (RDA) for fluoride is 3-4 mg for adults.
Drinking fluoridated water keeps teeth strong and protects teeth against onset and
development of cavities. Fluoride in drinking water reduces the incidence of dental caries.
Fluoridation of water is looked upon by many organizations as one of the accomplishments in
public health in the area of prevention of dental caries.

Fluoride absorption
Absorption of fluoride is quite efficient, almost 90% of fluoride is absorbed in the
gastrointestinal system. About 25% of fluoride is absorbed in the stomach and about 77% in
the small intestine. Most of the fluoride present in the body, that is 99% of it is found in bone
and teeth. Kidneys are the organs that are responsible for maintaining the fluoride
concentration in our bodies.

Dental caries and fluoride

Dental caries or tooth decay is one of the most common disorders that occur. It usually occurs
in children and young adults but can affect adults too. It is a condition in which the hard portion
of the tooth (enamel, dentine, and cement) are damaged by the bacteria in the mouth. Factors
that influence the development of caries on a tooth surface include saliva, diet, and genetic
factors.

Use of topical fluorides and consumption of fluoridated water and oral hygiene help to prevent
dental caries. When teeth are exposed regularly to fluoride during the time of development
fluoride provides a long-term protection against fluorosis and dental caries.

Excess consumption of fluoride
Fluoride consumed is absorbed from the gastrointestinal tract and excess fluoride is excreted
through urine. If excess fluorine is consumed it may lead to fluoride toxicity called fluorosis. The
negative effects of excess fluoride are teeth decay, osteoporosis and damage to kidneys, bones,
reproductive organs, nerve and muscle tissue.

Excess of fluoride may also interfere with thyroid gland function. Mottling of teeth is a
symptom of fluorosis in children and it occurs if the fluoride intake is too high in the first eight
years of life.