Diets against specific conditions

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.

Diets against hypertension
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.[7]
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,[8] 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".
Also, evidence shows that the Mediterranean diet improves cardiovascular outcomes.[9]

Weight control diets
Further information: Dieting
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.[10] 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.[10] At two years, all calorie-reduced diet types cause equal weight loss irrespective of the macronutrients emphasized.[11]

Diets to prevent cancer
Further information: Diet and cancer
A comprehensive worldwide report, Food, Nutrition, Physical Activity and the Prevention of Cancer: a Global Perspective, compiled by World Cancer Research Fund and American Institute for Cancer Research, reports that there is significant relation between lifestyle (including food consumption) and cancer prevention. The same report recommends eating mostly foods of plant origin and aiming to meet nutritional needs through diet alone, while limiting consumption of energy-dense foods, red meat, alcoholic drinks and salt and avoiding sugary drinks, processed meat and mouldy cereals (grains) or pulses (legumes).