As promised some words on vitamins, water and phytonutrients
in this continued series about food planning.
As with the minerals discussed previously, some vitamins are
recognized as essential nutrients, necessary in the diet for good health. Yet
Vitamin D is the exception: it can be synthesized in the skin, in the presence
of UVB radiation.
Certain vitamin-like compounds that are recommended in the diet, such as
carnitine, are thought useful for survival and health, but these are not
“essential” dietary nutrients because the human body has some capacity to
produce them from other compounds.
Moreover, thousands of different phytochemicals have recently been discovered in
food - particularly in fresh vegetables, which may have desirable properties
including antioxidant activity.
Vitamin deficiencies may result in disease conditions, including goiter, scurvy,
osteoporosis, impaired immune system, disorders of cell metabolism, certain
forms of cancer, symptoms of premature aging, and poor psychological health
including eating disorders, just to name a few. Excess levels of some vitamins
are also dangerous to your health, notably vitamin A. For at least one vitamin,
B6, toxicity begins at levels not far above the required amount.
Water is excreted from the body in multiple forms; including urine
and feces, sweating, and by water vapor in the exhaled breath. Therefore it is
necessary to adequately rehydrate to replace lost fluids.
Early recommendations for the quantity of water required for maintenance of good
health suggested that 6–8 glasses of water daily is the minimum to maintain
proper hydration. However the notion that a person should consume eight glasses
of water per day cannot be traced to a credible scientific source.
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.
While overhydrating is much less common than dehydration, it is also possible to
drink far more water than necessary which can result in water intoxication, a
serious and potentially fatal condition. In particular, large amounts of
de-ionized water are dangerous.
As cellular metabolism and energy production both require oxygen,
potentially damaging compounds known as free radicals are formed during these
processes. Most of these are oxidizers and some react very strongly.
For a continued normal cellular maintenance, growth, and division, these free
radicals must be sufficiently neutralized by antioxidant compounds. Recently,
some researchers suggested an interesting theory of evolution of dietary
antioxidants. Some are produced by the human body and there are some that the
body cannot produce and may only be obtained in the diet via direct sources such
as Vitamin C, Vitamin A, and Vitamin K. They can also be produced by the body
from other compounds such as Beta-carotene converted to Vitamin A and Vitamin D
synthesized from cholesterol by sunlight.
Phytochemicals and their subgroup, polyphenols, make up the majority of
antioxidants; about 4,000 are known. Different antioxidants are now known to
function in a cooperative network. 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. For example Vitamin A is fat-soluble and protects fat areas;
Vitamin C is water soluble and protects those areas.
When interacting with a free radical, some antioxidants produce a different free
radical compound that can be either less or more dangerous than the previous
compound. Having a variety of antioxidants allows any byproducts to be safely
dealt with by more efficient antioxidants neutralizing this free radical
Although initial studies suggested that antioxidant supplements might promote
health, later large clinical trials did not detect any benefit and suggested
instead that excess supplementation may be harmful. A varied diet of healthy
food items seems to still be the key.
A growing area of interest is the effect upon human health of
phytochemicals. These nutrients are typically found in edible plants, especially
colorful fruits and vegetables, but also other organisms including seafood,
algae, and fungi. One of the principal classes of phytochemicals is polyphenol
antioxidants, chemicals that are known to provide certain health benefits to the
cardiovascular system and immune system.
Discussing all of them in detail would lead us to fare and go beyond the scope
of this newspaper. But there is a list with a common overview of the most
important phytonutrients, their benefits and which food items they can be found