Adolescent nutrition appears to be one of those areas about which many health professions have an opinion, but not necessarily a solution. Adolescence is such an important time as it is the launching pad for adult life, and the perfect opportunity to start creating a healthy lifestyle to prepare for the future.
Adolescent Development - What's actually going on?
Piaget describes adolescence as the stage of the life in which the individual's thoughts start taking more of an abstract form and the egocentric thoughts decrease, allowing the individual to think and reason in wider perspective. 
"Adolescence" is obviously a highly researched topic, but many underestimate the critical importance of adolescent nutritional health. From approximately 10 to 20 years of age, an adolescent's body goes through intense changes.
Many studies have shown that the changes resulting from puberty and psychosocial development also influence nutritional requirements [ 10 & 3]. For example, soft tissues, organs and red blood cells increase in mass, and specifically bone mass has been shown to increase approximately 45% . It is highly important that the increase in nutritional needs is met.
Adolescence doesn't only mean physiological changes, but also psychosocial changes which allow the individual to think and reason in wider perspective.  As this period acts as a platform to spring into adulthood, it is important that good habits, along with well informed decisions, are established at this time.
What are the basic nutritional needs of adolescents?
Unfortunately due to difficult to access (and misleading!) information regarding the Recommended Daily Intake, there doesn't seem to be a clear answer to this question. For example, according to the Recommended Dietary Intake (RDI) set by the Australian Government, , the daily target for Vitamin C is 220 mg per day, which is equivalent to approximately 3 1/2 oranges (to clarify, that is 3 1/2 organic oranges grown in nutrient-dense soil, not 3 1/2 oranges from the local supermarket.). Having said this, various studies have shown that just meeting the RDI does not protect against many chronic diseases, but I'll come to this later!
A recent study of 90 schoolchildren aged 12 and 13 showed that during a double-blinded trial, the participant's cognitive ability and intelligence improved significantly when taking a multi-vitamin [ 7]. This shows that in order for adolescents to mature psychosocially, they need adequate nutrition. Omega 3 is a specific nutrient to mention here. Studies have shown that low omega 3 status correlates with ADHD behaviours and the disruption of a regular menstrual cycle during adolescence [15 & 17]. So, in short, if your adolescent isn't eating a substantial amount of low-pollutant fish, supplement with a high quality omega-3 supplement.
What are our adolescents actually eating?
Studies show that fewer than 2% of adolescents consume adequate amounts of all food groups and, worse still, 20% of females and 7% of males do not consume adequate portions of any of the food groups.  It's clear that most young people eat too much saturated fat and too few vegetables and fruits. For example, instead of consuming a well balanced, highly nutritious lunch, they may have a "Big Mac", which contains more than double the RDI sodium content, but does not even come close to the RDI of any minerals or vitamins. In short, on average, adolescents are not getting enough of the good stuff and are having far too much of the bad stuff!
Current trends and Influences: Why is adolescent nutrition in such a bad way?
It is hard to assess all the factors that influence a young person's dietary choices, as there are variations within different populations and communities, which cause changes in environmental factors. For example, obesity may be attributed not just to lifestyle choices, but also genetics , and the fast changes in nutritional trends may be due to social and political interventions and economic development . Not only this, but different aspects of adolescent food consumption behaviour may be influenced by factors that may also vary between males and females . It is obvious that adolescents often have chaotic eating patterns and do not always conform to dietary recommendations. But regardless of the trends, adequate nutrition is essential for development.
Where are we heading?
Based on the findings of various studies, the health of adolescents is only going to worsen over time. The period from the 1990s to today has seen a massive increase in obesity in adolescents, which has coincided with the increase in processed food. For example, a study of 4722 children to the age of 19 in 1999 - 2000, indicates the prevalence of overweight children in the United States is only going to increase. Specifically, the study showed that 15.5% of 12 to 19 year olds from 2000 were overweight, compared to 10.5% in 1994 .
Results like this are not isolated to the United States. In Brazil, in the years between 1975 and 1997, the percentage of overweight adolescents increased from 4.1% to 13.9% . In China, however, between the years of 1991 to 1997, the increase in overweight adolescents only increased 1.3% (from 6.4% in 1991 to 7.7% in 1997). If we look at the average diet of adolescents in China, it is still relatively unprocessed, balanced and contains many vegetables and lean protein.
Similar studies have presented almost identical results. For example, 4% of adolescents have metabolic syndrome and nearly 30% of overweight adolescents in the United States meet the criteria for metabolic syndrome . What is most alarming is that all of the metabolic derangements associated with metabolic syndrome, including Type 2 diabetes, are completely avoidable, simply by making healthier diet and lifestyle choices.
What is our future?
Unfortunately, based on the fact that significant proportions of obese adolescents become obese adults,  we may be burdened with a lot of public health problems in the future . For example, adult metabolic syndrome imposes a substantial risk for Type 2 diabetes and other health problems in the future. Simple deficiencies in various vitamins and minerals can lead to various health problems - for example, certain chronic forms of gastrointestinal disorders are associated with Vitamin K deficiencies .
Another prime example is calcium and Vitamin D. Deficiencies in calcium and Vitamin D have been linked to skeletal disorders, malignancies (particularly of the colon, breast, prostrate gland), chronic inflammatory conditions, rheumatoid arthritis, autoimmune diseases, metabolic disorders, Type 1 diabetes and the perturbation of cellular functions in the bones, kidneys and intestines [13, 14, 16]. It has also been suggested that the RDI of calcium and Vitamin D is inadequate  to prevent chronic disease. What does this mean for adolescents? Simply, it means that adolescents need to consume as much nutritionally dense food as possible and, if possible, supplement appropriately.
What is the solution?
Based on this information, you might suspect the future of the human population to be quite dim! But it is never too late to make a change - you know the old story "prevention is better than cure". Some simple steps to ensure optimal nutritional adolescent health may be:
* Eat as many organic and fresh vegetables and fruits as possible. Fruit and vegetables contain various minerals, vitamins and trace elements, as well as providing our body with a source of fibre.
* Ensure your diet is balanced, consisting of complex carbohydrates and good quality protein. Lean meat and complex carbohydrates are essential for adolescents' growing bodies, as they provide energy and valuable nutrients essential for growth.
* Nature does it best, so avoid synthetic and highly processed food. This includes artificial sugars, as well as junk food, cans of soft drink and, of course, alcohol.
* Eat as "organically" as possible. Adolescents are going through many hormonal changes during this time, and do not need the extra burden of artificial colours and flavours or the impact of xenoestrogens and pesticides on their system.
* Eat for a healthy mind. There is a significant link between our moods and what we eat. A healthy mind leads to a healthy body (and visa versa).
* Supplement wisely. In my opinion, supplementation is essential during adolescence, due to the poor quality of soil and feeding practices of animals. Look for supplements that are suitable for adolescents.
* Maintain a healthy lifestyle. This involves providing time for adolescents to exercise, continue their hobbies and to socialise. Encourage your young people to exercise in a fun way (such as in a sporting team) and empower them to make responsible decisions.
* Lastly, lead by example. Unfortunately, the "do what I say not what I do" model doesn't necessarily work with adolescents, as they learn by watching the behaviour of their parents. If you are a parent and want you adolescent child to exercise, maybe you could suggest exercising with them. That way, you are improving your health and leading them along the path to a healthier life.
Although we can start making these changes in the home, they need to be followed through. I applaud school canteens that are now stocking "healthy" options, but just because they stock them doesn't mean young people are necessarily buying them.
Obviously, more comprehensive programs need to be established to meet the nutritional, medical and psychosocial needs of adolescents, and nutrition and health professions need to tailor educational and treatment strategies, according to both the gender and the specific dietary outcomes of their clients [ 3 & 4]. Due to the increase in overweight youth, it is clear we need to focus on primary prevention and urgently implement measures to prevent further increases in obesity [5 & 6].
Further research is needed in the area of adolescent nutritional requirements. In the meantime, we know that prevention is better than cure, so making some simple lifestyle changes now may dramatically improve the quality of life in the future.
1. Journal of the American Medical Association (2000). Prevalence and Trends in Overweight Among US Children and Adolescents.
2. American Journal of Clinical Nutrition (2002). Trends of obesity and underweight in older children and adolescents in the United States, Brazil, China and Russia.
3. Journal of Public Health (2007). Nutritional status and lifestyles of adolescents from a public health perspective. The HELENA Project - Healthy Lifestyle in Europe by Nutrition in Adolescence.
4. Journal of Adolescent Health (1996). Influences on adolescent eating behaviour.
5. American Journal of Clinical Nutrition (2000). Energy and fat intakes of children and adolescents in the United States: data from the National Health and Nutrition Examination Surveys.
6. Archives of Pediatrics (2003). Prevalence of a Metabolic Syndrome Phenotype in Adolescents.
7. The Lancet (1988). Effect of Vitamin and Mineral supplementation on intelligence of a sample of school children.
8. Archives of Pediatric and Adolescent Medicine (1995). Overweight prevalence and trends for children and adolescents.
9. Nutrition (2004). Trends in nutritional status and stature among school-age children in Chile.
10. Journal of Pediatrics (2000). Nutrition in adolescence.
11. Pediatrics in Review (2002). Nutrition in adolescence.
12. American Journal of Nutrition (1985). The prevalence of vitamin K deficiency in chronic gastrointestinal disorders.
13. European Journal of Clinical Investigation (2005). Vitamin D and calcium deficits predispose for multiple chronic diseases.
14. American Journal of Clinical Nutrition (2004). Vitamin D: importance in the prevention of cancers, type 1 diabetes, heart disease, and osteoporosis.
15. Nutrition Journal (2008). Fatty acid status and behavioural symptoms of Attention Deficit Hyperactivity Disorder in adolescents: A case-control study.
16. American Journal of Clinical Nutrition (2004). Vitamin D and health in the 21st century: Bone and beyond.
17. American Journal of Obstetrics and Gynaecology (1995). Supplementation with omega-3 polyunsaturated fatty acids in the management of dysmenorrhoea in adolescents.
18. Journal of Pediatrics (1982). Progressive neuromuscular disease in children with chronic cholestasis and vitamin E deficiency: Diagnosis and treatment with alpha tocopherol.
19. Circulation (1999). Serum Glutathione in Adolescent Males Predicts Parental Coronary Heart Disease.
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