29
3.7.1 Vitamins and Minerals as Supplements
Today, multivitamin, multimineral, vitamin, and mineral supplements are the most
widely used dietary supplements (Bailey et al. 2013). Although adequate intake of
these micronutrients is required to maintain optimal health, the possibility of toxicity increases with increasing dose (Mulholland and Benford 2007). Because dietary
micronutrient deficiency is increasingly rare in developed countries, most supplement consumers actually have excess vitamin and mineral intake. Despite the widespread belief that vitamin and mineral supplements are beneficial to health, recent
reviews of vitamin and mineral supplement trials in community-dwelling adults
with no nutritional deficiencies have concluded that there is no clear evidence of
beneficial health effects. These include primary or secondary prevention of chronic
diseases including cardiovascular disease, cancer, and cognitive decline, as well as
effects on overall mortality (Guallar et al. 2013; Fortmann et al. 2013). Indeed, there
is evidence for possible harm from consumption of individual vitamins and mineral
in excess. Toxicity following consumption of water-soluble vitamins is rare.
However, photosensitivity and neurotoxicity have been reported at doses higher
than 500 mg/day of pyridoxine (vitamin B6) (Ziegler and Filer 1996), and cases of
pyridoxine-associated chronic sensory polyneuropathy have been reported in elderly
patients consuming multivitamin supplements (De Kruijk and Notermans 2005).
Reports of toxicity associated with overconsumption of supplemental antioxidant
fat-soluble vitamins are more prevalent. Vitamin E is a family of eight related
tocopherols and tocotrienols, of which α-tocopherol is the form generally used in
supplements. Doses of 800–1200 mg/day can result in bleeding associated with
antiplatelet action, and doses above 1200 mg/day can result in diarrhea, weakness,
blurred vision, and gonadal dysfunction (Ziegler and Filer 1996). Moreover, vitamin E supplementation following radiation therapy in a randomized trial of head
Table 3.1 Classification of supplements, examples and contents
Class
Example
Contents
Activator
Amino acids
Contains growth hormone and other
hormones
Carbohydrate
Dextrose
May contain vitamins and
electrolytes
Food and Food stuff
Fish oils, mineral and
vitamins
Contain garlic, kelp, royal jelly, yeast
Herbs
Ginseng, Fiber
Contains amino acids, other plant
source
Minerals
Selenium, multimineral
tablets
Contains only minerals
Multivitamins and
multiminerals
Vitamin D, calcium
supplement
Contains both mineral and vitamins
Oil supplements
Cod liver oil, primrose oil Contains oil base, with vitamins,
minerals
Vitamins
Vitamin C, vitamin B
Contains only vitamins
3 Dietary Supplements: Types, Health Benefits, Industry and Regulation
3.7.1 Vitamins and Minerals as Supplements
Today, multivitamin, multimineral, vitamin, and mineral supplements are the most
widely used dietary supplements (Bailey et al. 2013). Although adequate intake of
these micronutrients is required to maintain optimal health, the possibility of toxicity increases with increasing dose (Mulholland and Benford 2007). Because dietary
micronutrient deficiency is increasingly rare in developed countries, most supplement consumers actually have excess vitamin and mineral intake. Despite the widespread belief that vitamin and mineral supplements are beneficial to health, recent
reviews of vitamin and mineral supplement trials in community-dwelling adults
with no nutritional deficiencies have concluded that there is no clear evidence of
beneficial health effects. These include primary or secondary prevention of chronic
diseases including cardiovascular disease, cancer, and cognitive decline, as well as
effects on overall mortality (Guallar et al. 2013; Fortmann et al. 2013). Indeed, there
is evidence for possible harm from consumption of individual vitamins and mineral
in excess. Toxicity following consumption of water-soluble vitamins is rare.
However, photosensitivity and neurotoxicity have been reported at doses higher
than 500 mg/day of pyridoxine (vitamin B6) (Ziegler and Filer 1996), and cases of
pyridoxine-associated chronic sensory polyneuropathy have been reported in elderly
patients consuming multivitamin supplements (De Kruijk and Notermans 2005).
Reports of toxicity associated with overconsumption of supplemental antioxidant
fat-soluble vitamins are more prevalent. Vitamin E is a family of eight related
tocopherols and tocotrienols, of which α-tocopherol is the form generally used in
supplements. Doses of 800–1200 mg/day can result in bleeding associated with
antiplatelet action, and doses above 1200 mg/day can result in diarrhea, weakness,
blurred vision, and gonadal dysfunction (Ziegler and Filer 1996). Moreover, vitamin E supplementation following radiation therapy in a randomized trial of head
Table 3.1 Classification of supplements, examples and contents
Class
Example
Contents
Activator
Amino acids
Contains growth hormone and other
hormones
Carbohydrate
Dextrose
May contain vitamins and
electrolytes
Food and Food stuff
Fish oils, mineral and
vitamins
Contain garlic, kelp, royal jelly, yeast
Herbs
Ginseng, Fiber
Contains amino acids, other plant
source
Minerals
Selenium, multimineral
tablets
Contains only minerals
Multivitamins and
multiminerals
Vitamin D, calcium
supplement
Contains both mineral and vitamins
Oil supplements
Cod liver oil, primrose oil Contains oil base, with vitamins,
minerals
Vitamins
Vitamin C, vitamin B
Contains only vitamins
3 Dietary Supplements: Types, Health Benefits, Industry and Regulation