Back to basics in this multiple article series on nutrition
and food planning. What is nutrition, what are the components our body needs,
where do they come from and why do we need to plan our food intake. All of this
and more will be handled in the following few weeks.
Let’s start by having a shot at a definition of nutrition. Nutrition is the
provision, to cells and organisms, of the materials necessary to support life.
A fair warning to all, many common health problems can be prevented or
alleviated with a healthy diet. Maintaining an improper diet may have an
injurious impact on health, causing deficiency diseases such as scurvy and
health-threatening conditions like obesity and metabolic syndrome; and such
common chronic systemic diseases as cardiovascular disease, diabetes, and
There are six major classes of nutrients: carbohydrates, fats, minerals,
protein, vitamins, and water. A 7th class is added by some scientists,
consisting of micronutrients such as antioxidants and phytochemicals, which are
said to influence and protect certain bodily systems.
These nutrient classes can be categorized as either macronutrients which are
needed in relatively large amounts or micronutrients which are needed in smaller
quantities. The macronutrients include carbohydrates - including fiber, fats,
protein, and water. The micronutrients are minerals and vitamins.
Carbohydrates are basically saccharides or sugars, either simple or
complex, influencing the ratio of absorption into the body. They constitute a
large part of foods such as rice, noodles, bread, and other grain-based
products. Polysaccharides, the complex carbohydrates consist of long, multiple
branched chains of sugar units.
Traditionally, simple carbohydrates were believed to be absorbed quickly, and
therefore to raise blood-glucose levels more rapidly than complex carbohydrates.
This, however, is not accurate. Some simple carbohydrates, for example fructose,
found naturally in fruits, follow different metabolic pathways which result in
only a partial transformation to glucose, while many complex carbohydrates may
be digested at essentially the same rate as simple carbohydrates. Glucose
stimulates the production of insulin through food entering the bloodstream,
which is grasped by the beta cells in the pancreas.
Dietary fiber is a carbohydrate that is incompletely absorbed in
humans and in some animals. Dietary fiber consists mainly of cellulose, a large
carbohydrate polymer that is indigestible because humans do not have the
required enzymes to disassemble it. There are two subcategories: soluble and
insoluble fiber. Whole grains, fruits - especially plums, prunes, and figs - and
vegetables are good sources of dietary fiber. There are many health benefits of
a high-fiber diet. Dietary fiber helps reduce the chance of gastrointestinal
problems such as constipation and diarrhea by increasing the weight and size of
stool and softening it. Insoluble fiber, found in whole wheat flour, nuts and
vegetables, especially stimulates peristalsis – the rhythmic muscular
contractions of the intestines which move your food along the digestive tract.
Soluble fiber, found in oats, peas, beans, and many fruits, dissolves in water
in the intestinal tract to produce a gel which slows the movement of food
through the intestines. This may help lower blood glucose levels because it can
slow the absorption of sugar. Additionally, fiber, perhaps especially that from
whole grains, is thought to possibly help lessen insulin spikes, and therefore
reduce the risk of type 2 diabetes.
Saturated fats, typically from animal sources, have been a staple in
many world cultures for millennia. Unsaturated fats such as vegetable oil are
considered healthier, while trans-fats are to be avoided. Saturated and some
trans-fats are typically solid at room temperature, such as butter or lard,
while unsaturated fats are typically liquids such as olive oil or flaxseed oil.
Trans fats are very rare in nature, and have been shown to be highly detrimental
to human health.
Essential fatty acids
Most fatty acids are non-essential, meaning the body can produce them
as needed, generally from other fatty acids and always by expending energy to do
so. However, in humans, at least two fatty acids are essential and must be
included in the diet. An appropriate balance of essential fatty acids—omega-3
and omega-6 fatty acids—seems also important for health. A balance between
omega-3 and omega-6 is believed important for cardiovascular health. In
industrialized societies, people typically consume large amounts of processed
vegetable oils, which have reduced amounts of the essential fatty acids along
with too much of omega-6 fatty acids relative to omega-3 fatty acids. The ratio
of omega-3 versus omega-6 has wide effects on general health, and specific
effects on immune function and inflammation, and cell division.