Chapter 12. Micronutrients for Bones
Fluoride
Role of Fluoride
Fluoride is known mostly as the mineral that combats tooth decay. It assists in tooth and bone development and maintenance. Fluoride combats tooth decay via three mechanisms:
- Blocking acid formation by bacteria
- Preventing demineralization of teeth
- Enhancing remineralization of destroyed enamel
Fluoride is added to drinking water in 45% of communities in Canada. In British Columbia, only 3.7% of the population has access to fluoridated water. Fluoridated water, on average, prevents 27 percent of cavities in children and between 20 and 40 percent of cavities in adults, however, it can be expensive.
The optimal fluoride concentration in water to prevent tooth decay ranges between 0.7–1.2 milligrams per liter. Exposure to fluoride at three to five times this concentration before the growth of permanent teeth can cause fluorosis, which is the mottling and discoloring of the teeth.
A severe case of fluorosis caused by excessive fluoride exposure. Figure 12.7 portrays discolored teeth with brown, yellow, or black stains and visible enamel damage.
Fluoride’s benefits to mineralized tissues of the teeth are well substantiated, but the effects of fluoride on bone are not as well known. Fluoride is currently being researched as a potential treatment for osteoporosis. The data are inconsistent on whether consuming fluoridated water reduces the incidence of osteoporosis and fracture risk. Fluoride does stimulate osteoblast bone-building activity, and fluoride therapy in patients with osteoporosis has been shown to increase bone mineral density. In general, it appears that at low doses, fluoride treatment increases bone mineral density in people with osteoporosis and is more effective in increasing bone quality when the intake of calcium and vitamin D is adequate.
Dietary Reference Intake for Fluoride
The Adequate Intakes (AI) for fluoride are available, but RDAs have not yet been developed. The AIs are based on the doses of fluoride shown to reduce the incidence of cavities, but not cause dental fluorosis. From infancy to adolescence, the AIs for fluoride increase from 0.01 milligrams per day for ages less than six months to 2 milligrams per day for those between the ages of fourteen and eighteen. In adulthood, the AI for males is 4 milligrams per day and 3 milligrams per day for females. The UL for young children is 1.3 and 2.2 milligrams per day for girls and boys, respectively. For adults, the UL is set at 10 milligrams per day.
Age Group | AI (mg/day) | UL (mg/day) |
Infants (0–6 months) | 0.01 | 0.7 |
Infants (6–12 months) | 0.50 | 0.9 |
Children (1–3 years) | 0.70 | 1.3 |
Children (4–8 years) | 1.00 | 2.2 |
Children (9–13 years) | 2.00 | 10.0 |
Adolescents (14–18 years) | 3.00 | 10.0 |
Adult Females (> 19 years) | 3.00 | 10.0 |
Adult Males (> 19 years) | 4.00 | 10.0 |
Data Source: (“Dietary Reference Intakes,” 1997)[1] |
Dietary Sources of Fluoride
Food | Serving | Fluoride (mg) | Percent Daily Value* |
Fruit Juice | 3.5 fl oz. | 0.02-2.1 | 0.7-70 |
Crab, canned | 3.5 oz. | 0.21 | 7 |
Rice, cooked | 3.5 oz. | 0.04 | 1.3 |
Fish, cooked | 3.5 oz. | 0.02 | 0.7 |
Chicken | 3.5 oz. | 0.015 | 0.5 |
* Current AI used to determine Percent Daily Value | |||
Data Source: (“Fluoride,” 2015)[2] |
Consuming Too Little Fluoride
Insufficient fluoride intake can play a role in dental cavities.
Consuming Too Much Fluoride
Exposure to high fluoride concentrations before the growth of permanent teeth can cause fluorosis, which is the mottling and discoloring of the teeth.
- Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride. January 1, 1997. http://www.iom.edu/Reports/1997/Dietary-Reference-Intakes-for-Calcium-Phosphorus-Magnesium-Vitamin-D-and-Fluoride.aspx.. ↵
- Micronutrient Information Center: Fluoride. Oregon State University, Linus Pauling Institute. lpi.oregonstate.edu/mic/minerals/fluoride . Updated in April 29, 2015. Accessed October 22, 2017. ↵