ANSC 420 Lecture Notes - Lecture 7: Purified Water, Glutathione, Water Intoxication

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For those who have healthy kidneys, it is somewhat difficult to drink too much water, but
(especially in warm humid weather and while exercising) it is dangerous to drink too little.
People can drink far more water than necessary while exercising, however, putting them at risk
of water intoxication, which can be fatal. In particular large amounts of de-ionized water are
dangerous.
Normally, about 20 percent of water intake comes in food, while the rest comes from drinking
water and assorted beverages (caffeinated included). Water is excreted from the body in multiple
forms; including urine and feces, sweating, and by water vapor in the exhaled breath.
Other micronutrients include antioxidants and phytochemicals. These substances are generally
more recent discoveries which have not yet been recognized as vitamins or as required.
Phytochemicals may act as antioxidants, but not all phytochemicals are antioxidants.
Antioxidants are a recent discovery. As cellular metabolism/energy production requires oxygen,
potentially damaging (e.g.mutation causing) compounds known as free radicals can form. Most
of these are oxidizers (i.e. acceptors of electrons) and some react very strongly. For normal
cellular maintenance, growth, and division, these free radicals must be sufficiently neutralized by
antioxidant compounds. Some are produced by the human body with
adequate precursors (glutathione, Vitamin C) and those the body cannot produce may only be
obtained in the diet via direct sources (Vitamin C in humans, Vitamin A,Vitamin K) or produced
by the body from other compounds (Beta-carotene converted to Vitamin A by the body, Vitamin
Dsynthesized from cholesterol by sunlight). Phytochemicals (Section Below) and their subgroup
polyphenols are the majority of antioxidants; about 4,000 are known. Different antioxidants are
now known to function in a cooperative network, e.g. vitamin C can reactivate free radical-
containing glutathione or vitamin E by accepting the free radical itself, and so on. Some
antioxidants are more effective than others at neutralizing different free radicals. Some cannot
neutralize certain free radicals. Some cannot be present in certain areas of free radical
development (Vitamin A is fat-soluble and protects fat areas, Vitamin C is watersoluble and
protects those areas). When interacting with a free radical, some antioxidants produce a different
free radical compound that is less dangerous or more dangerous than the previous compound.
Having a variety of antioxidants allows any byproducts to be safely dealt with by more efficient
antioxidants in neutralizing a free radical's butterfly effect.
A growing area of interest is the effect upon human health of trace chemicals, collectively
called phytochemicals. These nutrients are typically found in edible plants, especially colorful
fruits and vegetables, but also other organisms including seafood, algae, and fungi. The effects of
phytochemicals increasingly survive rigorous testing by prominent health organizations. One of
the principal classes of phytochemicals are polyphenol antioxidants, chemicals which are known
to provide certain health benefits to the cardiovascular system and immune system. These
chemicals are known to down-regulate the formation of reactive oxygen species, key chemicals
in cardiovascular disease.
Perhaps the most rigorously tested phytochemical is zeaxanthin, a yellow-pigmented carotenoid
present in many yellow and orange fruits and vegetables. Repeated studies have shown a strong
correlation between ingestion of zeaxanthin and the prevention and treatment of age-related
macular degeneration (AMD). Less rigorous studies have proposed a correlation between
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