Carbohydrates

Carbohydrates are a main dietary component and considered a macronutrient (1). The liver breaks down carbohydrates into glucose (blood sugar) which contributes energy to the body, particularly the brain and the nervous system (2). Carbohydrates are classified in two groups, simple, which are sugars, and complex, which are starches and fibre (2). Complex carbohydrates include whole grain breads and cereals, starchy vegetables and legumes. Simple carbohydrates naturally contain vitamins and minerals and include fruits, vegetables, milk and milk products. Simple carbohydrates are also found in refined sugars (2). The healthiest diet obtains carbohydrates, vitamins, and other nutrients in as natural a form as possible (example: from fruit instead of table sugar) (2).

1. Linus Pauling http://lpi.oregonstate.edu/infocenter/glossary.html#carbohydrate
   
2. U.S. National Library and the National Institute of Health
           http://www.nlm.nih.gov/medlineplus/ency/article/002469.htm#Definition

Fibre

Fibre is a term used to describe a group of carbohydrates that cannot be digested (1). There are different ways of classifying fibre; one way is according to solubility (1). Nuts, seeds, legumes, oats, apples, pears and berries are good sources of soluble fibre, which may reduce the risk of cardiovascular disease (1)(2). Vegetables and whole grains are good sources of insoluble fibre, which is important in bowel health and may reduce the risk of diverticular disease. Despite what was once thought, high fibre intake does not appear to be associated with reducing the risk of colon cancer (1)(2).  However, there is strong evidence to suggest that diets rich in cereal fibre may reduce the risk of cardiovascular disease, and diabetes (1)(2). Consuming adequate amounts of both types of fibre is key to maintaining a healthy body.  

1. Harvard School of Public Health http://www.hsph.harvard.edu/nutritionsource/fiber.html
2. Linus Pauling http://lpi.oregonstate.edu/infocenter/phytochemicals/fiber/

Pectin is one of the soluble fibres found in fruits and berries (1). As a soluble fibre, pectin's slow stomach emptying, delays the absorption of some nutrients in the intestine and lower blood cholesterol levels (1). Studies have shown that supplementation with pectin can lower cholesterol level (1).

 1.   Linus Pauling http://lpi.oregonstate.edu/infocenter/phytochemicals/fiber/

Vitamins

Vitamin A

Vitamin A is a fat-soluble vitamin that helps in the production and activity of white blood cells, takes part in bone remodelling, maintains endothelial cells (those that line the interior of the body), helps enhance night vision and regulates cell growth and division (1). Because of its role in regulating cell growth and division, scientists have investigated whether insufficient vitamin A played a role in cancer development. Several studies dispute this conclusion (1).

1.  Harvard School of Public Health  http://www.hsph.harvard.edu/nutritionsource/vitamins.html

Vitamin C

Vitamin C is a water-soluble vitamin and antioxidant that is essential to many of the body's functions (1). It is required in the production of collagen, which is a tissue needed for healthy bones, teeth, gums and blood vessels (1). Because of vitamin C's antioxidant activity, it has been studied for its potential protective benefits in heart disease, cancer, eye diseases, the common cold and other health conditions but studies have demonstrated no clear relationship (1). There is research that suggests that high intake of vitamin C can reduce the risk of heart disease, some cancers, stroke and cataracts - but also evidence that there is no significant association between vitamin C intake and disease risk (2).  Despite the belief that high doses of vitamin C can inhibit the common cold, there is little evidence to support this (1). Further research is necessary to determine the role of vitamin C in health care and to separate its effects from diets high in fruits and vegetables (2).

1.  Harvard School of Public Health  http://www.hsph.harvard.edu/nutritionsource/vitamins.html
   
2. Linus Pauling http://lpi.oregonstate.edu/infocenter/vitamins/vitaminC/
   

Vitamin B6

Vitamin B6 has many essential functions. It is important in nervous system function, red blood cell formation, niacin formation, hormone function and nucleic acid synthesis (1). Vitamin B6, along with vitamin B12 and folate, help in the recycling of homocysteine – a building block of protein (2). High levels of homocysteine are associated with increased risk of heart disease and stroke (1). Some studies have shown that high intakes of these vitamins may be cardioprotective while others have not been able to make significant associations (2). Further research should clarify the relationship between B vitamins and cardiovascular disease.

1. Linus Pauling http://lpi.oregonstate.edu/infocenter/vitamins/vitaminB6
2. Harvard School of Public Health http://www.hsph.harvard.edu/nutritionsource/vitamins.html

Folate

Folate is a water-soluble B vitamin (1). The term folate means foliage in Italian reflecting its abundance in leafy plants. Folate is required for the synthesis and maintenance of new cells. Folate is important for all women who may become pregnant, as adequate folate intakes during the time just before and after a woman becomes pregnant, serves to protect against a number of congenital malformations including neural tube defects (NTD) (1). Low intakes of folate may increase the level of the amino acid homocysteine normally found in blood. There is some evidence that an elevated homocysteine level is an independent risk factor for heart disease (1).

1.  Linus Pauling http://lpi.oregonstate.edu/infocenter/vitamins/fa

Vitamin K

Vitamin K is a fat-soluble vitamin found in many food sources, especially cooking oils and leafy green vegetables (1). Vitamin K’s major role is in blood clotting, though research is now showing that it may also have a role in bone development (1).  For this reason, scientists are investigating the relationship between high intakes of vitamin K and osteoporosis (1)(2).  While some studies have shown an association between intake and hip fractures, this is still considered a weak relationship and further long-term investigation is required (2).

1. Harvard School of Public Health  http://www.hsph.harvard.edu/nutritionsource/vitamins.html 
   
2. Linus Pauling http://lpi.oregonstate.edu/infocenter/vitamins/vitaminK/
   

Thiamin (Vitamin B1)

Thiamin also known as vitamin B1, is a water-soluble B-complex vitamin that is involved in many metabolic functions (1). The body requires thiamin to break down carbohydrates, fat and protein. It is also required for the proper functioning of nerve cells (1).

1.  Linus Pauling http://lpi.oregonstate.edu/infocenter/vitamins/thiamin/index.html
   

Niacin (Vitamin B3)

Niacin also known as vitamin B3, is a water-soluble B-complex vitamin that is involved in the metabolic pathways that break down carbohydrates, fats and proteins into energy, and in the synthesis of fatty acids and cholesterol (1).

1. Linus Pauling http://lpi.oregonstate.edu/infocenter/vitamins/niacin/
   

Minerals

Potassium

Potassium is an essential dietary mineral (often referred to as an electrolyte) which along with sodium and chloride helps to regulate the fluid balance in the body. Potassium is also critical for muscle (heart tissue) and nerve function (1). Fruits and vegetables are the richest sources of potassium (1). Scientists continue to examine the inverse association between potassium intakes and stroke, high blood pressure, osteoporosis and kidney stone interventions (1). 

1. Linus Pauling  http://lpi.oregonstate.edu/infocenter/minerals/potassium/
   

Magnesium

Magnesium is an essential mineral for the human body needed for numerous functions including the formation of essential molecules such as proteins and lipids. It is also important for the structure of bone and cell membranes (1).

1. Linus Pauling  http://lpi.oregonstate.edu/infocenter/minerals/magnesium
   

Manganese

Manganese is an important mineral element  that is a cofactor in many enzymatic reactions. It is essential for cartilage and bone development (1).

1. Linus Pauling http://lpi.oregonstate.edu/infocenter/minerals/manganese/

Calcium

Calcium is a mineral important to bone and tooth development, blood clotting, nerve cell communication and regulation of the heart (1). The majority of calcium in the body is found in the bones and teeth (2).  The rest of calcium is found in soft tissue and blood, where levels are very tightly regulated to ensure proper physiological functioning (2).  When blood levels of calcium drop too low, calcium from the bone is transferred to the blood (2).  Sufficient calcium intake is important to ensuring a healthy skeleton. While dairy sources are well know to be rich sources of calcium, it can also be obtained from plant sources (2).

1. Harvard School of Public Health http://www.hsph.harvard.edu/nutritionsource/calcium.html
2. Linus Pauling http://lpi.oregonstate.edu/infocenter/minerals/calcium/
   

Selenium

Selenium is one of the body’s essential minerals (1)(2). It is required in minute (trace) amounts, and can be toxic in larger amounts. It is part of several selenium-dependent enzymes, enabling reactions which prevents free-radical formation in the body (antioxidant activity). Selenium is also part of the enzyme that activates thyroid hormone, normal growth, development and metabolism (1)(2). The best food sources of selenium are seafood and meat. Plants will absorb more if grown in selenium rich soil; there is a wide variation in the selenium content of grains and other plants (2). Most of the soil in North America is selenium-rich. Studies in areas of the world with selenium-poor soils have found some association with greater risk of cancer and comprised immunity. In well-nourished populations, however, the disease-prevention role of larger amounts of selenium intake is still under investigation (2).

1. Whitney, E.N & Rolfes, S.R., (2002).  Understanding Nutrition (9th ed.). Toronto: Wadsworth Thomson Learning.
2. Linus Pauling   http://lpi.oregonstate.edu/infocenter/minerals/selenium/
   

Iron

Iron is a micronutrient vital to many of the body’s functions, primarily as a part of numerous proteins and enzymes. Chiefly, iron is a component of heme, a compound that makes up both the hemoglobin protein in red blood cells and the myoglobin protein in muscle cells (1).  The role of these proteins is to transport and store oxygen throughout the body (2).  Iron also plays a key role in energy metabolism (2).  In addition, as part of an enzyme required for DNA synthesis, iron has a direct effect on growth, healing, immune function and reproduction (2).  While iron can be found in many foods, the type of iron contained affects how well the body can efficiently absorb it.  Meat, fish, poultry contain heme iron, which is the most effectively absorbed.  Legumes, vegetables and grains are good sources of iron but they consist of the non-heme form that is not as well absorbed by the body, an important consideration for vegetarians (1).

1. Whitney, E.N & Rolfes, S.R., (2002).  Understanding Nutrition (9th ed.). Toronto: Wadsworth Thomson Learning.
2. Linus Pauling http://lpi.oregonstate.edu/infocenter/minerals/iron/
   

Copper

Copper is an essential trace element. Some of the physiologic functions known to be copper dependent are; energy production, connective tissue formation, central nervous system functions and antioxidant functions (1).

1. Linus Pauling  http://lpi.oregonstate.edu/infocenter/minerals/copper/index.html
   

Phytochemical

PhytoChemicals

PhytoChemicals are plant chemicals that may have potential benefits to health but are not considered essential nutrients (1). Research is being conducted to determine the roles of various phytochemicals such as carotenoids and flavonoids in disease conditions, yet associations remain inconclusive.  While numerous studies have shown the benefits of eating a diet high in fruits and vegetables, it remains to be seen whether benefits can be attributed to individual phytochemicals or to other characteristics of the foods that they are found in (1).

1. Linus Pauling http://lpi.oregonstate.edu/infocenter/phytochemicals.html

Allicin

Allicin is a compound which breaks down to produce organosulfur compounds. These compounds are currently under investigation for their potential to prevent and treat disease (1).

1. Linus Pauling http://lpi.oregonstate.edu/infocenter/phytochemicals/garlic
   

Anthocyanidins

Anthocyanidins are a subclass of flavonoids (1).  Some common food sources of anthocyanidins are red, blue and purple berries, red and purple grapes and red wine (1). These chemicals have been associated with improved blood vessel health in humans and animals (2). 

1. Linus Pauling http://lpi.oregonstate.edu/infocenter/phytochemicals/flavonoids/
2. 5 a day The Colour Way http://www.5aday.org/html/phytochem/anthocyanidins.php
   

Ellagic Acid

Ellagic Acid is part of the polyphenol subclass of phytochemicals (1).  Common sources of ellagic acid are blueberries, blackberries, red grapes, raspberries, strawberries, cranberries and pomengranates (1,2). Cell culture and animal studies have shown that ellagic acid may slow the growth of some tumors and may cause the death of cancer cells in the lab (2). While research on ellagic acid is promising, there is no evidence yet to suggest that ellagic acid is benefitical in humans (2). Further studies are necessary to determine what protective benefits ellagic acid may have in the human body.

1. 5 a day The Colour Way  http://www.5aday.org/html/phytochem/ellagic_acid.php
   
2. American Cancer Society         http://www.cancer.org/docroot/ETO/content/ETO_5_3X_Ellagic_Acid.asp?sitearea=ETO
   

Flavonoids

Flavonoids are a large family of phytochemical compounds produced by plants (1). Scientists are interested in the potential health benefits of flavonoids associated with fruit and vegetable-rich diets. Higher intakes of flavonoid-rich foods are associated with a reduction in cardiovascular disease risk, but it is not yet known whether flavonoids themselves are cardioprotective.

1. Linus Pauling http://lpi.oregonstate.edu/infocenter/phytochemicals/flavonoids/
   

Glucosinolates

The glucosinolate family of phytochemicals is found in all cruciferous vegetables such as broccoli, cauliflower, cabbage, brussel sprouts, radishes, etc. (1)(2). Glucosinolates are responsible for the unique taste of these vegetables. Because glucosinolates are water-soluble, some loss may occur when boiling cruciferous vegetables; therefore it is preferable to reduce cooking time, and to use steaming or microwave methods (2). A plant enzyme will break down the glucosinolates into compounds such as indoles and isothiocyanates, which are under intense investigation for their potential anti-carcinogenic properties (2).

1. Cruciferous Vegetables: Cancer Protective Mechanisms of Glucosinolate Hydrolysis Products and Selenium
   http://0-scholarsporal.info.innopac.lib.ryerson.ca/pdflinks/06052813033417050.pdf
2. Linus Pauling http://lpi.oregonstate.edu/infocenter/phytochemicals/isothio#intro
   

Indole-3-carbinole

Indole-3-carbinole is a product of the breakdown of  glucosinolates in brassica vegetables like broccoli, cauliflower, brussel sprouts and kale (1). Indole-3-carbinole is being studied for its anti-carcinogenic properties, but to date animal studies have been inconclusive (1). While some evidence has supported the possibility that higher intake of cruciferous vegetables can reduce cancer risk, more research is necessary to determine what role phytochemicals such as indoles and glucosinolates play, either alone or in synergy with other compounds such as vitamin C, selenium and fibre, to provide protective benefits (1).

1. Linus Pauling http://lpi.oregonstate.edu/infocenter/phytochemicals/i3c/
   

Proanthocyanidins

Proanthocyanidins are flavonols, another subclass of flavonoids (1). They can be found in chocolate, apples, berries, red grapes and red wine (1).  Proanthocyanidins are being studied for their potentially preventative role in heart disease, cancer and urinary tract infections (2).

1. Linus Pauling http://lpi.oregonstate.edu/infocenter/phytochemicals/flavonoids/
2. 5 a day The Colour Way http://www.5aday.org/html/phytochem/proanthocyanidins.php
   

Inulin

Inulin is the term used to describe a group of compounds that are naturally occurring in plants as storage carbohydrates (1). Some common plants that contain inulin include wheat, onions, bananas and chicory (1). Inulin will often be described along with oligofructose, which is a derivative of inulin (1).  Inulin and oligofructose are indigestible by the upper gastrointestinal tract and thus have a reduced caloric value; they promote the growth of intestinal bacteria; and they have a stabilizing effect on blood glucose and insulin secretion (1).  These compounds are being used commercially as fibre supplements and to improve the taste and texture of low-calorie and low-fat foods respectively (1). 

1. Ninness (1999). http://jn.nutrition.org/cgi/content/full/129/7/1402S#SEC1

Quercetin

Quercetin is considered one of the most widely distributed flavonoids in the diet. Some of the best sources include apples, onions, citrus fruits, teas and red wine (1)(2). Quercetin is being investigated for the role it may play in the prevention of heart disease, eye disease, arthritis, allergies and prostate health (2).

1. 5 a day The Colour Way http://www.5aday.org/html/phytochem/flavonols.php
2. University of Maryland Medical Centre
           http://www.umm.edu/altmed/ConsSupplements/Quercetincs.html#Uses
   

Resveratrol

Resveratrol falls into the polyphenol class of phytochemicals (1).This is a group of compounds believed to have antioxidant and anti-inflammatory properties (1). Common sources of resveratrol are grapes, grape juice, red wine, some berries and peanuts (1)(2). Resveratrol is of interest to scientists studying heart disease because of its abundance in red wine and red wine’s association with the French Paradox (2). Lab studies have demonstrated resveratrol’s cardioprotective effects in test tube experiments but there has yet to be any convincing evidence in human trials (2). Studies on lung cells demonstrated the anti-inflammatory properties of resveratrol, which may suggest a potential for reduced risk of lung disease and asthma (1). Animal and culture studies have also shown some possible role for resveratrol in cancer prevention and increased lifespan but its effects on humans is still unknown (2).

1. 5 a day The Colour Way  http://www.5aday.org/html/phytochem/resveratrol.php 
   
2. Linus Pauling http://lpi.oregonstate.edu/infocenter/phytochemicals/resveratrol/
   

Rutin

Rutin is a derivative of quercetin. It is being studied for its antioxidant properties.

Carotenoids

Carotenoids

Carotenoids are the class of pigments that give plants their red, yellow and orange colour (1). Frequently consumed carotenoids include beta-carotene, lycopene, lutein & zeaxanthin (1). Carotenoids can be characterized by their provitamin A activity – that is, their ability to convert to vitamin A in the body (1).  Beta-carotene is a provitamin A carotenoid while lycopene, lutein & zeaxanthin do not have provitamin A activity.  Fruits and vegetables provide the majority of the carotenoids in the North American diet (1). In plants, carotenoids function as antioxidants. However, the health benefits of this antioxidant activity in the human body are still unclear (1). It would appear that the most essential function of carotenoids is as a source of vitamin A.  Currently, epidemiological studies are being conducted to determine the carotenoids role in heart disease, some cancers and some eye diseases.

1. Linus Pauling http://lpi.oregonstate.edu/infocenter/phytochemicals/carotenoids/

Beta-Carotene

Beta-carotene is the carotenoid that gives fruits and vegetables their orange and yellow colour (1). Rich sources of beta-carotene include carrots, winter squash, sweet potatoes and even spinach (the green pigment hides the underlying orange and yellow pigments) (1). Beta-carotene has provitamin A activity, which means that it can convert to vitamin A in the body (1).  Beta-carotene has been studied for its role in some cancers and heart disease.  No consistent association has been found between consumption of beta-carotene alone and reduced lung cancer risk but there may be a potential inverse relationship between total carotenoid intake and lung cancer risk (1).  However, beta-carotene supplementation and high-risk populations (such as smokers) showed a possible increased risk of lung cancer (1).  While the results of several prospective studies indicate that people with higher intakes of carotenoid-rich fruits and vegetables are at lower risk of cardiovascular disease, it is not yet clear whether this effect is a result of carotenoids or other factors associated with diets high in carotenoid-rich fruits and vegetables (1).  Further research is necessary.

1. Linus Pauling http://lpi.oregonstate.edu/infocenter/phytochemicals/carotenoids/
   

Lutein & Zeaxanthin

Lutein & Zeaxanthin are the carotenoids found in the eye’s retina (1).  While they do not have provitamin A activity, they may have an antioxidant function during light absorption (1). They are efficient absorbers of blue light and may potentially prevent oxidative damage, which may play a role in reducing the risk of age-related macular degeneration (ARMD), a leading cause of blindness in North America (1). Some studies have suggested that high consumption of these carotenoids is associated with a lower risk of ARMD, while other studies have shown no such relationship (1).  Further study is necessary to clarify the relationship between dietary lutein and zeaxanthin and the reduced risk of ARMD.  In addition, due to the fact that lutein and zeaxanthin are the only carotenoids found in the eye, there is interest in the role they may play in cataract prevention (1). Recent studies have shown that high consumption of foods rich in these carotenoids resulted in reduced cataract development (1). However, further studies are necessary to determine the role of lutein & zeaxanthin and/or foods rich in these compounds in cataract development.  Dark green leafy vegetables are rich sources of lutein & zeaxanthin (1).

1. Linus Pauling http://lpi.oregonstate.edu/infocenter/phytochemicals/carotenoids/#armd

Lycopene

Lycopene is the carotenoid that gives tomatoes, pink grapefruit, watermelon and guava their red colour (1). While small amounts can be found in a number of fruits and vegetables, tomatoes – particularly when cooked and processed – are the predominant source of lycopene in our diets (1). Lycopene does not have provitamin A activity, which means that the body does not convert this carotenoid into vitamin A (1).  However, it is considered an effective antioxidant as it is readily absorbed and distributed throughout the body (2). Epidemiological, animal and experimental studies have suggested that lycopene may have a role in heart disease and some types of cancer prevention particularly prostrate cancer (2). However, further research is necessary to determine lycopene’s and/or the tomato’s function in disease prevention (3).

1. Linus Pauling http://lpi.oregonstate.edu/infocenter/phytochemicals/carotenoids/index.html
   
2. Rao & Agarwal (2000) http://www.cmaj.ca/cgi/content/full/163/6/739
   
3. Harvard School of Public Health http://www.hsph.harvard.edu/nutritionsource/fruits.html#references
   

Antioxidants

Antioxidants are substances that act as free-radical scavengers (1). They protect and defend against highly reactive metabolism by-products (free-radicals) that can cause cell damage in the human body (1).  Fruits and vegetables contain an abundance of antioxidants that come in the form of vitamins, minerals or phytochemicals (2). Some well-known antioxidants are vitamin C, vitamin E, selenium, and the carotenoids (2).  Antioxidants have been investigated for their role in the prevention and treatment of cancer, heart disease, eye diseases and other health conditions (2). So far, there has been little evidence in human trials to suggest that individual antioxidants have specific protective benefits, despite some promising lab and animal studies (2). Because of the complex makeup of fruits and vegetables, it is difficult to determine the effects of each individual component without considering the interactions of all the components together (2).  Research continues to be done to further clarify the role of antioxidants in our diet.

1. Linus Pauling  http://lpi.oregonstate.edu/infocenter/glossary.html
   
2. Harvard School of Public Health  http://www.hsph.harvard.edu/nutritionsource/vitamins.html
   

Protein

There are two types of protein that come from foods (1). Complete proteins come from meat and dairy sources, while incomplete proteins come from plant sources such as vegetables, bean, nuts and grains (1). Vegetarians, or people who consume a mostly plant based diet, should take care to consume protein from a variety of sources (1). While protein makes up many of the building blocks that power the body’s functions, little is known about protein’s role in chronic disease (1).

1.  Harvard School of Public Health http://www.hsph.harvard.edu/nutritionsource/protein.html