Healthy diet

Leafy green, allium, and cruciferous vegetables are key components of a healthy diet

Common colorful culinary fruits. Apples, pears, strawberries, oranges, bananas, grapes, canary melons, watermelon, cantaloupe, pineapple and mango.

A healthy diet is one that helps to maintain or improve overall health.

A healthy diet provides the body with essential nutrition: fluid, adequate essential amino acids from protein,^[1] essential fatty acids, vitamins, minerals, and adequate calories. The requirements for a healthy diet can be met from a variety of plant-based and animal-based foods. A healthy diet supports energy needs and provides for human nutrition without exposure to toxicity or excessive weight gain from consuming excessive amounts. Where lack of calories is not an issue, a properly balanced diet (in addition to exercise) is also thought to be important for lowering health risks, such as obesity, heart disease, type 2 diabetes, hypertension and cancer.^[2]

Various nutrition guides are published by medical and governmental institutions to educate the public on what they should be eating to promote health. Nutrition facts labels are also mandatory in some countries to allow consumers to choose between foods based on the components relevant to health.

The idea of dietary therapy (using dietary choices to maintain health and improve poor health) is quite old and thus has both modern scientific forms (medical nutrition therapy) and prescientific forms (such as dietary therapy in traditional Chinese medicine).

Recommendations

World Health Organization

The World Health Organization (WHO) makes the following 5 recommendations with respect to both populations and individuals:^[3]

• Eat roughly the same amount of calories that your body is using. A healthy weight is a balance between energy consumed and energy that is 'burnt off'.
• Limit intake of fats, and prefer less unhealthy unsaturated fats to saturated fats and trans fats.
• Increase consumption of plant foods, particularly fruits, vegetables, legumes, whole grains and nuts.
• Limit the intake of sugar. A 2003 report recommends less than 10% simple sugars.^[4]
• Limit salt / sodium consumption from all sources and ensure that salt is iodized.

Other recommendations include:

• 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).

United States Department of Agriculture

The Dietary Guidelines for American by the United States Department of Agriculture (USDA) recommends three healthy patterns of diet, summarized in table below, for a 2000 kcal diet.^[5][6] Food group amounts per day, unless noted per week.

Food group/subgroup (units)	Healthy US patterns	Healthy Vegetarian patterns	Healthy Med-style patterns
Fruits (cup eq)	2	2	2.5
Vegetables (cup eq)	2.5	2.5	2.5
Dark green	1.5/wk	1.5/wk	1.5/wk
Red/orange	5.5/wk	5.5/wk	5.5/wk
Starchy	5/wk	5/wk	5/wk
Legumes	1.5/wk	3/wk	1.5/wk
Others	4/wk	4/wk	4/wk
Grains (oz eq)	6	6.5	6
Whole	3	3.5	3
Refined	3	3	3
Dairy (cup eq)	3	3	2
Protein Foods (oz eq)	5.5	3.5	6.5
Meat (red and processed)	12.5/wk	--	12.5/wk
Poultry	10.5/wk	--	10.5/wk
Seafood	8/wk	--	15/wk
Eggs	3/wk	3/wk	3/wk
Nuts/seeds	4/wk	7/wk	4/wk
Processed Soy (including tofu)	0.5/wk	8/wk	0.5/wk
Oils (grams)	27	27	27
Solid fats limit (grams)	18	21	17
Added sugars limit (grams)	30	36	29

American Heart Association / World Cancer Research Fund / American Institute for Cancer Research

The American Heart Association, World Cancer Research Fund, and American Institute for Cancer Research recommends a diet that consists mostly of unprocessed plant foods, with emphasis a wide range of whole grains, legumes, and non-starchy vegetables and fruits. This healthy diet is replete with a wide range of various non-starchy vegetables and fruits, that provide different colors including red, green, yellow, white, purple, and orange. They note that tomato cooked with oil, allium vegetables like garlic, and cruciferous vegetables like cauliflower, provide some protection against cancer. This healthy diet is low in energy density, which may protect against weight gain and associated diseases. Finally, limiting consumption of sugary drinks, limiting energy rich foods, including “fast foods” and red meat, and avoiding processed meats improves health and longevity. Overall, researchers and medical policy conclude that this healthy diet can reduce the risk of chronic disease and cancer.^[7][8]

Harvard School of Public Health

The Nutrition Source of Harvard School of Public Health makes the following 10 recommendations for a healthy diet:^[9]

• Choose good carbohydrates: whole grains (the less processed the better), vegetables, fruits and beans. Avoid white bread, white rice, and the like as well as pastries, sugared sodas, and other highly processed food.^[10]
• Pay attention to the protein package: good choices include fish, poultry, nuts, and beans. Try to avoid red meat.^[11]
• Choose foods containing healthy fats. Plant oils, nuts, and fish are the best choices. Limit consumption of saturated fats, and avoid foods with trans fat.^[9]
• Choose a fiber-filled diet which includes whole grains, vegetables, and fruits.^[12]
• Eat more vegetables and fruits—the more colorful and varied, the better.^[9]
• Calcium is important, but milk is not its best or only source. Good sources of calcium are collards, bok choy, fortified soy milk, baked beans, and supplements which contain calcium and vitamin D.^[13]
• Water is the best source of liquid. Avoid sugary drinks, and limit intake of juices and milk. Coffee, tea, artificially-sweetened drinks, 100-percent fruit juices, low-fat milk and alcohol can fit into a healthy diet but are best consumed in moderation. Sports drinks are recommended only for people who exercise more than an hour at a stretch to replace substances lost in sweat.^[14]
• Limit salt intake. Choose more fresh foods, instead of processed ones.^[9]
• Moderate alcohol drinking has health benefits, but is not recommended for everyone.^[9]
• Daily multivitamin and extra vitamin D intake has potential health benefits.^[9]

Other than nutrition, the guide recommends frequent physical exercise and maintaining a healthy body weight.^[9]

For 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.

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 has a useful effect to reduce blood pressure, both in people with hypertension and in people with normal blood pressure.^[15]

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,^[16] 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.^[17]

WHO recommends few standards such as an intake of less than 5 grams per person per day so as to prevent one from cardiovascular disease. Unsaturated fatty acids with polyunsaturated vegetable oils, on the other hand plays an essential role in reducing coronary heart disease risk as well as diabetes.^[18]

Obesity

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 divided into four categories: low-fat, low-carbohydrate, low-calorie, and very low calorie.^[19] 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.^[19] At two years, all calorie-reduced diet types cause equal weight loss irrespective of the macronutrients emphasized.^[20]

Reduced disease risk

There may be a relationship between lifestyle including food consumption and potentially lowering the risk of cancer or other chronic diseases. A diet high in fruits and vegetables appears to decrease the risk of cardiovascular disease and death but not cancer.^[21]

A healthy diet may consist mostly of whole plant foods, with limited consumption of energy dense foods, red meat, alcoholic drinks and salt while reducing consumption of sugary drinks, and processed meat.^[22] A healthy diet may contain non-starchy vegetables and fruits, including those with red, green, yellow, white, purple or orange pigments. Tomato cooked with oil, allium vegetables like garlic, and cruciferous vegetables like cauliflower "probably" contain compounds which are under research for their possible anti-cancer activity.^[7][8]

A healthy diet is low in energy density, lowering caloric content, thereby possibly inhibiting weight gain and lowering risk against chronic diseases.^[7][8][23] Chronic Western diseases are associated with pathologically increased IGF-1 levels. Findings in molecular biology and epidemiologic data suggest that milk consumption is a promoter of chronic diseases of Western nations, including atherosclerosis, carcinogenesis and neurodegenerative diseases.^[24]

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.^[25]

The WHO estimates that 2.7 million deaths are attributable to a diet low in fruits and vegetables every year.^[25] Globally it is estimated to cause about 19% of gastrointestinal cancer, 31% of ischaemic heart disease, and 11% of strokes,^[2] thus making it one of the leading preventable causes of death worldwide.^[26]

Popular diets

Popular diets, often referred to as fad diets, make promises of weight loss or other health advantages such as longer life without backing by solid science, and in many cases are characterized by highly restrictive or unusual food choices.^[27][28]:296 Celebrity endorsements (including celebrity doctors) are frequently associated with popular diets, and the individuals who develop and promote these programs often profit handsomely.^{[29][30]:11–12}

Public health

Fears of high cholesterol were frequently voiced up until the mid-1990s. However, more recent research has shown that the distinction between high- and low-density lipoprotein ('good' and 'bad' cholesterol, respectively) must be addressed when speaking of the potential ill effects of cholesterol. Different types of dietary fat have different effects on blood levels of cholesterol. For example, polyunsaturated fats tend to decrease both types of cholesterol; monounsaturated fats tend to lower LDL and raise HDL; saturated fats tend to either raise HDL, or raise both HDL and LDL;^[31][32] and trans fat tend to raise LDL and lower HDL.

While dietary cholesterol is only found in animal products such as meat, eggs, and dairy, studies have not found a link between eating cholesterol and blood levels of cholesterol.^[33]

Vending machines in particular have come under fire as being avenues of entry into schools for junk food promoters. However, there is little in the way of regulation and it is difficult for most people to properly analyze the real merits of a company referring to itself as "healthy." Recently, the United Kingdom removed the rights for McDonald's to advertise its products, as the majority of the foods that were seen have low nutrient values and high fat counts were aimed at children under the guise of the "Happy Meal". The British Heart Foundation released its own government-funded advertisements, labeled "Food4Thought", which were targeted at children and adults displaying the gory nature of how fast food is generally constituted.

Cultural and psychological factors

From a psychological and cultural perspective, a healthier diet may be difficult to achieve for people with poor eating habits.^[34] This may be due to tastes acquired in childhood and preferences for sugary, salty and/or fatty foods.^[35]

See also

• List of diets
• Meals
• Table of food nutrients

References

1. "ESSENTIAL AMINO ACID REQUIREMENTS: A REVIEW".
2. "WHO | Promoting fruit and vegetable consumption around the world". WHO.
3. "WHO | Diet". WHO.
4. "WHO/FAO release independent Expert Report on diet and chronic disease". World Health Organization. Retrieved 21 February 2011.
5. Dietary Guidelines Advisory Committee. "Scientific Report of the 2015 Dietary Guidelines Advisory Committee." Washington (DC): USDA and US Department of Health and Human Services (2015).
6. "App. E-3.7: Developing Vegetarian and Mediterranean-style Food Patterns - 2015 Advisory Report - health.gov". health.gov. Retrieved 2015-09-30.
7. "Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective" (PDF). Washington DC: AICR, 2007. ISBN 978-0-9722522-2-5.
8. "American Cancer Society Guidelines on Nutrition and Physical Activity for Cancer Prevention" (PDF). Last Revised: 1/11/2012.
9. "What Should I Eat?". The Nutrition Source. Harvard School of Public Health. Retrieved 17 October 2012.
10. "Carbohydrates".
11. "Protein: Moving Closer to Center Stage". Retrieved October 1, 2014.
12. "The Bottom Line: Choose a fiber-filled diet, rich in whole grains, vegetables, and fruits". Retrieved October 27, 2012.
13. "The Bottom Line: Calcium is important. But milk isn’t the only, or even best, source". Retrieved October 27, 2012.
14. "The Nutrition Source Healthy Beverage Guidelines". Retrieved October 27, 2012.
15. He FJ, MacGregor GA. Effect of longer-term modest salt reduction on blood pressure. Cochrane Database of Systematic Reviews 2004, Issue 1. Art. No.: CD004937. doi:10.1002/14651858.CD004937.
16. "Your Guide To Lowering Your Blood Pressure With DASH" (PDF). Retrieved 2009-06-08.
17. Walker C, Reamy BV (April 2009). "Diets for cardiovascular disease prevention: what is the evidence?". Am Fam Physician 79 (7): 571–7. PMID 19378874.
18. "WHO - Unhealthy diet". who.int.
19. Strychar I (January 2006). "Diet in the management of weight loss". CMAJ 174 (1): 56–63. doi:10.1503/cmaj.045037. PMC 1319349. PMID 16389240.
20. Sacks FM, Bray GA, Carey VJ, et al. (February 2009). "Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates". N. Engl. J. Med. 360 (9): 859–73. doi:10.1056/NEJMoa0804748. PMC 2763382. PMID 19246357.
21. Wang, X; Ouyang, Y; Liu, J; Zhu, M; Zhao, G; Bao, W; Hu, FB (Jul 29, 2014). "Fruit and vegetable consumption and mortality from all causes, cardiovascular disease, and cancer: systematic review and dose-response meta-analysis of prospective cohort studies.". BMJ (Clinical research ed.) 349: g4490. doi:10.1136/bmj.g4490. PMC 4115152. PMID 25073782.
22. EXECUTIVE SUMMARY Policy and Action for Cancer Prevention Food, Nutrition, and Physical Activity. 2010. p. 1. ISBN 978-0-9722522-5-6.
23. "Cancer Trends Progress Report - Fruit and Vegetable Consumption". Retrieved 2012-07-14.
24. Melnik B. (Apr 2009). "Milk consumption: aggravating factor of acne and promoter of chronic diseases of Western societies.". J Dtsch Dermatol Ges. 7 (4): 364–70. doi:10.1111/j.1610-0387.2009.07019.x. PMID 19243483.
25. "WHO | Diet and physical activity: a public health priority".
26. Lopez AD, Mathers CD, Ezzati M, Jamison DT, Murray CJ (May 2006). "Global and regional burden of disease and risk factors, 2001: systematic analysis of population health data". Lancet 367 (9524): 1747–57. doi:10.1016/S0140-6736(06)68770-9. PMID 16731270.
27. Jennifer Robbins, Silvina Pugliese, Diana Cullum-Dugan, Carine Lenders, Kathy Gorman Ireland Popular Diets Page accessed Jan 28, 2016
28. What to Eat. New York: North Point Press (Farrar, Straus and Giroux). 2006. p. 611. ISBN 978-0-86547-738-4.
29. Tina Gianoulis, "Dieting" in the St. James Encyclopedia of Popular Culture Ed. Thomas Riggs. Vol. 2. 2nd ed. Detroit: St. James Press, 2013. p106-108. ISBN 978-1-55862-847-2
30. Fitzgerald M (2014). Diet Cults: The Surprising Fallacy at the Core of Nutrition Fads and a Guide to Healthy Eating for the Rest of US. Pegasus Books. ISBN 978-1-60598-560-2.
31. Mensink RP, Zock PL, Kester ADM, Katan MB (May 2003). "Effects of dietary fatty acids and carbohydrates on the ratio of serum total to HDL cholesterol and on serum lipids and apolipoproteins: a meta-analysis of 60 controlled trials". American Journal of Clinical Nutrition 77 (5): 1146–1155. ISSN 0002-9165. PMID 12716665.
32. Thijssen, M.A. and R.P. Mensink. (2005). Fatty Acids and Atherosclerotic Risk. In Arnold von Eckardstein (Ed.) Atherosclerosis: Diet and Drugs. Springer. pp. 171–172. ISBN 978-3-540-22569-0.
33. "Part D. Chapter 1: Food and Nutrient Intakes, and Health: Current Status and Trends - Continued". Office of Disease Prevention and Health Promotion. 2015. Retrieved 12 May 2015.
34. "Told to Eat Its Vegetables, America Orders Fries" article by Kim Severson in The New York Times September 24, 2010, accessed September 25, 2010
35. James WP (2008). "The fundamental drivers of the obesity epidemic". Obesity Research. 9 Suppl 1 (Mar;9 Suppl 1:6-13): 6–13. doi:10.1111/j.1467-789X.2007.00432.x. PMID 18307693.

External links

• Diet, Nutrition and the prevention of chronic diseases, by a Joint WHO/FAO Expert consultation (2003)