A lot of people manage to include fresh fruit in their daily diet by consuming fresh juice. In fact, there is a common belief that a glass of fresh juice is a healthy habit of high nutritional value. Yet, several surveys and dietary guidelines recommended by top Universities, such as the Harvard School of Public Health, have shown that fresh juice should be avoided, even the one we make at home; instead, we should opt for the whole fruit.

This fact has surprised a lot of people since drinking fruit juice -especially orange juice is believed to be an excellent source of vitamins and antioxidants- thus good for our health. But why is this happening?

To make a glass of fresh orange juice we need 3-4 oranges, which are far more than we would normally consume if we ate the whole fruit. According to the expert Susan Jebb, head of the Department of Research for Human Nutrition at the University of Cambridge, a glass of fresh orange juice contains a large amount of sugar, mainly fructose, which is absorbed very fast. Thus our body cannot distinguish whether we had an orange juice or a Coke.

Of course, this is not happening if we eat the whole fruit, especially with its skins or peels. This way, we receive many fibres and antioxidants which reduce the speed with which fructose is being absorbed. Also, whole fruit consumption results in a higher sense of repletion and balances any negative effects of fructose on metabolism.

Fructose is metabolized in the liver the same way as alcohol

Fructose is converted to triglycerides, which when produced in small amounts, they are a valuable source of energy in muscles. However, when we consume high amounts of fructose, more than our body needs, there is a significant deposition of fat which is observed primarily in the liver and then in the rest of the body.

Fructose and alcohol have a similar effect on the liver.

The human body can metabolize approximately 25gr of fructose per day. This amount of fructose can be reached from just two fruit servings. A glass of fresh juice contains about 40gr of fructose which is absorbed into our blood very fast.
An excessive consumption of fresh juice and other beverages that contain fructose is closely related to fat deposition in the liver, obesity, inflammation and insulin resistance.

Apart from the impact to the fat tissue, the intake of fructose is responsible for liver inflammation, as well as, cellular stress. Both these are factors that promote the development of chronic inflammation in the liver (non-alcoholic steatohepatitis) which can further lead to cirrhosis.

Moreover, excessive intake of fructose is closely related to the communication dysfunction between the liver and the intestine, muscles and adipose tissue, significantly affecting the metabolic balance of the organism.

Children, fructose, and physical activity

Children and people that exercise a lot can consume up to 4-5 fruit a day, due to their increased physical activity. In this case, produced triglycerides are immediately used for energy production in the muscles, without having any negative effects on the organism.

It is worth mentioning that fruit produced in the past, used to be smaller and sourer with lower fructose content compared to the fruit produced today. As a result, excessive consumption of fruit should be avoided.

alternatively, we can consume vegetable juice, which does not contain fructose or we can include one or two fruits in our daily diet with low sugar content, such as forest fruits.

To Your Health! 

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• Skip the juice, go for whole fruit. Amy Roeder, Harvard School of Public Health. https://news.harvard.edu/gazette/story/2013/08/reduce-type-2-diabetes-risk/
• Fruit consumption and risk of type 2 diabetes: results from three prospective longitudinal cohort studies. Isao Muraki et al. BMJ 2013; 347. http://www.bmj.com/content/347/bmj.f5001
• How fruit juice went from health food to junk food https://www.theguardian.com/science/2014/jan/12/remove-fruit-juice-sugar-five-a-guidance-government-health-adviser
• A dose-response study of consuming high-fructose corn syrup–sweetened beverages on lipid/lipoprotein risk factors for cardiovascular disease in young adults. Kimber L Stanhope et al. Am J Clin Nutr. 2015 Jun. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4441807/
• Fructose: It’s “Alcohol Without the Buzz” Robert H. Lustig. Department of Pediatrics and the Philip R. Lee Institute for Health Policy Studies, University of California, San Francisco, CA . Adv Nutr March 2013 http://advances.nutrition.org/content/4/2/226.abstract
• The Sweet Path to Metabolic Demise: Fructose and Lipid Synthesis Mark A. Herman. Volume 27, Issue 10, p719–730, October 2016 REVIEWS http://www.cell.com/trends/endocrinology-metabolism/fulltext/S1043-2760(16)30066-2  
• Fructose and NAFLD: The Multifaceted Aspects of Fructose Metabolism. Prasanthi Jegatheesan and Jean‐Pascal De Bandt. Department of Physiology, University of Lausanne, Switzerland. Faculty of Pharmacy, Paris Descartes University, Sorbonne Paris, France. Clinical Chemistry Department, Hôpitaux Universitaires Paris, France. Nutrients. 2017 Mar; 9(3): 230.