Fruit and Vegetables: Health Benefits, Antioxidants and Weight Management
Antioxidants are scavengers of unstable molecules free radicals. Free radicals can cause damage to cells, impair the immune system leading to infections and degenerative diseases including cancer and heart disease.
Antioxidants reduce oxidative stress and help protect our body from aging and disease. People who regularly consume fruits and vegetables rich in polyphenols (such as berries) have been shown to have a lower risk of cancer, heart disease and also some neurological diseases. It is estimated that one third of all cancers in western countries are directly related to nutrition.
Polyphenols are brightly coloured plant chemicals that have beneficial health properties. Different fruits and vegetables contain differing amounts and types of polyphenols. These polyphenols can have very different actions in the body, therefore the best approach to improving your antioxidant levels is to regularly consume a wide range of different coloured fruits and vegetables, including colourful berries.
Antioxidants – Why are they so important?
The cells in our body are constantly changing, cells are constantly being destroyed and new cells are forming, this is what accounts for our body’s growth. Free radicals are unstable molecules that cause damage to cells, impair the immune system, leading to infections and degenerative diseases including heart disease and cancer. They are produced naturally in our body and they are created by external factors including UV light, radiation, infections, medications, heavy metals, cigarette smoke, pollution and synthetic chemicals. People who are very active will have increased antioxidant requirements.
When antioxidants are lacking, free radicals attack other molecules to stabilise themselves, which causes a vicious cycle, this is called oxidative stress.
Damage caused by oxidative stress may be associated with the pathogenesis of many human diseases including Alzheimer’s disease, Parkinson’s disease, cardiovascular disease, rheumatoid arthritis and complications in diabetes. Therefore it is important to both minimise exposure to external factors that cause free radical production and also to increase our antioxidant status. Also by preventing free radical damage, antioxidants can slow the effects of aging. Many cosmetic companies are aware of this and are incorporating more and more antioxidant compounds into their products. However antioxidants don’t only work topically to slow premature ageing; internally they can protect the structural tissue fibres, such as collagen and elastin to prevent sagging and loss of skin elasticity and tone. Antioxidants also protect organs and blood vessels from free radicals, thereby helping to maintain their youthful function.
Cancer and Diet
Increased cancer risk is associated with specific diets. Figure 1 shows the large percentage of cancer deaths caused by dietary factors. The link between diet and cancer is well known (1-3). Dietary intake is the largest factor influencing cancer. The American Institute for Cancer Research (AICR) has made many studies demonstrating the link between diet and cancer risk (4). AICR recommends increased or regular consumption of vegetables, fruits, whole grains, and legumes, and discourages excess consumption of sugary and energy-dense foods and drinks, red and processed meats, processed foods high in salt.
Fruit and Vegetables and Weight Management
More and more evidence suggests that increasing fruit and vegetable intake will assist in maintaining weight and prevent obesity (6,7). Energy density is reduced by a larger intake of fruit and vegetables (8). Eating more fruits and vegetables results in feeling fuller for longer and displaces more energy dense foods (7). People eat a consistent volume of food, no matter what the energy content of the food is, therefore, eating low energy dense fruit and vegetables can assist in managing weight, feeling fuller for longer, and improve diet quality (5,9,10). Increasing fruit and vegetable intake is a global public health nutrition priority and a main focus of population health in Australia (11-17).
An easy way to ensure you’re getting the proper balance of food is using the plate model. Half of your plate should be filled with fruit and/or vegetables and one quarter with potato or rice or pasta and one quarter meat, fish or poultry for every meal. Also, One quarter fruit and dairy products which are represented outside the circle.
- Society AC, editor. American Cancer Society. Atlanta; 2004. Cancer Facts and Figures. http://www.cancer.org/acs/groups/content/@epidemiologysurveilance/documents/document/acspc-028323.pdf.
- Calle EE, Kaaks R. Overweight, obesity and cancer: epidemiological evidence and proposed mechanisms. Nat Rev Cancer. 2004;4(8):579–591.
- Hursting SD, Berger NA. Energy balance, host-related factors, and cancer progression. J Clin Oncol. 2010;28(26):4058–4065.
- Research WCRFAIfC. Food, Nutrition, and Physical Activity, and the Prevention of Cancer: A Global Perspective. In. Washington DC: AICR; 2007.
- Rolls BJ, Drewnowski A, Ledikwe JH: Changing the Energy Density of the Diet as a Strategy for Weight Management. Journal of the American Dietetic Association 2005, 105(5, Supplement 1):98-103.
- Bazzano LA: The high cost of not consuming fruits and vegetables. Journal of the American Dietetic Association 2006, 106(9):1364-1368.
- Tohill BC: Dietary intake of fruit and vegetables and management of body weight. World Health Organization; 2005.
- Haslam DW, James WPT: Obesity. Lancet 2005, 366(9492):1197-1209.
- Rolls B, Ello-Martin J, Tohill B: What can intervention studies tell us about the relationship between fruit and vegetable consumption and weight management? Nutrition Reviews 2004, 62(1):1-17.
- Ledikwe J, Blanck H, Kettel Khan L, Serdula M, Seymour J, Tohill B, Rolls B: Dietary energy density is associated with energy intake and weight status in US adults. American Journal of Clinical Nutrition 2006, 83(6):1362-1368.
- World Health Organization: Diet, Nutrition and the Prevention of Chronic Disease. In WHO Technical Report Series 916. Geneva: World Health Organization; 2003.
- Strategic Inter-Governmental Nutrition Alliance: Position statement. Eat Well: the benefits of vegetables and fruit. Melbourne: National Public Health Partnership; 2000.
- National Public Health Partnership: Australia’s National Action Plan to increase consumption of Fruit and Vegetables. Melbourne: National Public Health Partnership; 2000.
- Strategic International Nutrition Alliance: Eat Well Australia: An Agenda for Action for Public Health Nutrition. Canberra National Public Health Partnership; 2001.
- Department of Health in Western Australia: Eat Well Move Well WA-public health nutrition and physical activity plan for action 2002–2010. Perth: Department of Health in Western Australia; 2002.
- Miller M, Shiell A, Stafford H: An Intervention Portfolio to Promote Fruit and Vegetable Consumption. Part 1 – The Process and Portfolio. Melbourne: National Public Health Partnership; 2000.
- Miller M, Stafford H: An Intervention Portfolio to Promote Fruit and Vegetable Consumption. Part 2 – Review of Interventions. Melbourne: National Public Health Partnership; 2000.
- Gundgaard J, Nielsen J, Olsen J, Sorensen J: Increased intake of fruit and vegetables: estimation of impact in terms of life expectancy and healthcare costs. Public Health Nutrition 2003, 6(1):25-30.
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