Feb 15 – Antioxidants
What if you consume too much beta-carotene?
• Large quantities don't appear to be toxic
• Skin can turn yellow (carotenoderma)
• Taking beta-carotene supplements isn’t recommended as they aren’t
associated with any health benefits
What if you don't consume enough beta-carotene?
• There are no deficiency symptoms
• Vitamin A is a fat soluble vitamin
• Excessive vitamin A is stored in the liver, adipose tissue, kidneys and lungs
There are 3 active forms of Vitamin A:
• Retinoic acid
Functions of Vitamin A:
• Essential to proper vision
• Antioxidant, protecting LDL cholesterol
• Cell differentiation – the process by which cells mature and specialize
• Sperm production and fertilization
• Bone growth Recommended intake for Vitamin A
• Unit for RDA is retinol activity coefficient (RAE)
• 1 RAE = 1 microgram (µg) retinol
• 1 RAE = 12 µg beta-carotene
• RRA of Vitamin A is 900 RAE/day for men; 700 RAE/day for women
Sources of Vitamin A
• Obtained from animal sources of retinol (liver, eggs) and plant sources of
provitamin A carotenoids (dark green, organge, and deep yellow fruits and
• Foods fortified with vitamin A in Canada include reduced fat milks, plant-
based milks, margarine
What if you consume too much vitamin A?
• Vitamin A is highly toxic, especially from supplements
• Birth defects and permanent damage to the liver and eyes can result
• Provitamin A (carotene) intake doesn’t contribute to toxicity
• Liver shouldn’t be consumed frequently by children and pregnant women
What if you don't consume enough vitamin A?
• Night blindedness is the most common disease of vitamin A deficiency; it is
• Later, irreversible blindness occurs due to drying of cornea
• Other deficiency symptoms include: impaired immunity and growth failure
• Selenium is a trace mineral found in a few amino acids in the body Functions of selenium
• Antioxidant: part of glutathione peroxidase enzyme system
• Production of thyroxine – a thyroid hormone
Recommended intake of Selenium
• 55 milligrams per day for men and women
• UL of selenium is 400 miligrams per day
Sources of Selenium
• High sources include organ meats, pork, seafood and nuts
• Plant sources such as wheat, rice, depend on soil levels of selenium
What if you consume too much selenium?
• Selenium toxicity (brittle hair, nails, skin rashes) can result from supplements
What if you don't consume enough selenium?