A healthy diet is one that helps maintain or improve health. It is important for the prevention of many chronic disease such as: obesity, heart disease, diabetes, and cancer.

A healthy diet involves consuming appropriate amounts all of the food groups, including an adequate amount of water. Nutrients can be obtained from many different foods, so there are a wide variety of healthy diets.

Overview

The World Health Organisation (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 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. A select few plants (such as soy and hemp) give all the essential acids. A combination of other plants may also provide all essential amino acids (except rice and beans which have limitations).
• 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).

Fruits and vegetables

The WHO recommends a minimum of 400g of fruit and vegetables per day. This groups excludes potatoes and other starchy tubers. Fruits and vegetables also prevent several micronutrient deficiencies.

Meat

Some evidence shows an increased mortality with high red meat intake.

Salt

While a moderate amount of salt is required for health, a high salt diet can have detrimental effects on blood pressure.Fact: date=April 2009

Unhealthy diets

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.

Food additive controversy

Some claim that food additives, such as artificial sweeteners, colorants, preserving agents, and flavorings may cause health problems such as increasing the risk of cancer or ADHD.