A
healthy diet is one that helps maintain or improve health. It is important for
lowering many chronic health risks, such as obesity, heart disease, diabetes,
hypertension and cancer. A healthy diet involves consuming appropriate amounts
of all essential nutrients and an adequate amount of water. Nutrients can be
obtained from many different foods, so there are numerous diets that
may be
considered healthy. A healthy diet needs to have a balance of macronutrients
(fats, proteins, and carbohydrates), calories to support energy needs, and
micronutrients to meet the needs for human nutrition without inducing toxicity
or excessive weight gain from consuming excessive amounts.
There
are a number of diets and recommendations by numerous medical and governmental
institutions that are designed to promote certain aspects of health.
The
World Health Organization (WHO) makes the following 5 recommendations with
respect to both populations and individuals:
Achieve an energy balance and a healthy
weight
Limit energy intake from total fats and
shift fat consumption away from saturated fats to unsaturated fats and towards
the elimination of trans-fatty acids
Increase consumption of fruits and
vegetables, legumes, whole grains and nuts
Limit the intake of simple sugar. A 2003
report recommends less than 10% simple sugars.
Limit salt / sodium consumption from all
sources and ensure that salt is iodized
Other
recommendations include:
Sufficient essential amino acids
("complete protein") to provide cellular replenishment and transport
proteins. All essential amino acids are present in animals. Some plants (such
as quinoa, soy and hemp) give all the essential acids. A combination of other
plants in a diet may also provide all essential amino acids. Fruits such as
avocado and pumpkin seeds also have all the essential amino acids.[4][5]
Essential micronutrients such as vitamins
and certain minerals.
Avoiding directly poisonous (e.g. heavy
metals) and carcinogenic (e.g. benzene) substances;
Avoiding foods contaminated by human
pathogens (e.g. E. coli, tapeworm eggs).
The
American Heart Association recommends a diet rich in fruits, vegetables, healthful
fatty acids and limited saturated fat.
In
addition to dietary recommendations for the general population, there are many
specific diets that have primarily been developed to promote better health in
specific population groups, such as people with high blood pressure (as in low
sodium diets or the more specific DASH diet), or people who are overweight or
obese (in weight control diets). However, some of them may have more or less
evidence for beneficial effects in normal people as well.
A
low sodium diet is beneficial for people with high blood pressure. A Cochrane
review published in 2008 concluded that a long term (more than 4 weeks) low
sodium diet in Caucasians has a useful effect to reduce blood pressure, both in
people with hypertension and in people with normal blood pressure.
The
DASH diet (Dietary Approaches to Stop Hypertension) is a diet promoted by the
National Heart, Lung, and Blood Institute (part of the NIH, a United States
government organization) to control hypertension. A major feature of the plan
is limiting intake of sodium, and it also generally encourages the consumption
of nuts, whole grains, fish, poultry, fruits and vegetables while lowering the
consumption of red meats, sweets, and sugar. It is also "rich in potassium,
magnesium, and calcium, as well as protein". Evidence shows that the
Mediterranean diet improves cardiovascular outcomes.
Weight
control diets aim to maintain a controlled weight. In most cases dieting is
used in combination with physical exercise to lose weight in those who are
overweight or obese.
Diets
to promote weight loss are generally divided into four categories: low-fat,
low-carbohydrate, low-calorie, and very low calorie. A meta-analysis of six
randomized controlled trials found no difference between the main diet types
(low calorie, low carbohydrate, and low fat), with a 2–4 kilogram weight loss
in all studies. At two years, all calorie-reduced diet types cause equal weight
loss irrespective of the macronutrients emphasized.
An
unhealthy diet is a major risk factor for a number of chronic diseases
including: high blood pressure, diabetes, abnormal blood lipids,
overweight/obesity, cardiovascular diseases, and cancer.
The
WHO estimates that 2.7 million deaths are attributable to a diet low in fruit
and vegetable every year. Globally it is estimated to cause about 19% of
gastrointestinal cancer, 31% of ischaemic heart disease, and 11% of strokes,
thus making it one of the leading preventable causes of death worldwide.
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