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Updated 03 March 2015

The fructose controversy

Some say high intake of fructose is to blame for obesity, cardio vascular disease and metabolic syndrome while others say is a sugar like any other. DietDoc investigates.

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Fructose, which is a so-called ‘simple sugar’ found in honey, fruit, vegetables and other plant materials, has been in the spotlight for more than 20 years.

On the one hand some researchers link a high intake of fructose to a wide variety of metabolic ills, including obesity, non-alcoholic fatty liver disease, raised uric acid levels, increased triglyceride levels which may cause cardiovascular disease, and the metabolic syndrome.

On the other hand, other researchers are dedicated to proving that fructose is a sugar like any other, that it has no special effects on disease or expanding waistlines and that any changes in the health of the global population are not due to fructose itself, but are merely due to an increased kilocalorie or kilojoule intake.

Read: Why teenagers get fat

Background

Ever since Grant (1998) investigated both the high incidence of triglyceridaemia (raised blood levels of fats know as triglycerides) and heart disease on the island of St Helena, which he attributed to increased liver synthesis of triglycerides from the fructose found in table sugar, scientists have been studying fructose and its possible link to the epidemics of various diseases of lifestyle that many populations suffer from.

Read: Obesity in SA - where will it end?

Until the 1960s sucrose was used exclusively to sweeten food, but then the food industry developed High-Fructose Corn Syrup (HFCS), which is much sweeter than sucrose and glucose and a great deal cheaper than sugar produced from sugar cane.

The use of HFCS in the USA rocketed and by 1985 sucrose consumption had dropped by 50%, while the average fructose intake increased by 42%. By 2004, Americans, particularly children and adolescents, were already consuming an average of nearly 50g of fructose a day (Tappy & Lê, 2010).

Read: SA women the fattest in Africa

HFCS became the sweetener of choice in the USA for processed foods and particularly sweetened cold drinks.

In South Africa we have not yet experienced this HFCS explosion because most of our sweetened beverages and prepared foods contain sucrose derived from sugar cane.

Ironically foods and drinks that are manufactured so as to be free of sucrose, often contain fructose instead. It is, therefore, always a good idea to read the ingredients list on all food labels.

Researchers were quick to liken the steep increase in fructose intake in the States to the exponentially increasing obesity in young and old. This parallel increase in obesity and the intake of sugar (fructose) sweetened beverages (SSBs) was regarded as a cause for grave concern.

SSBs include the following: still and carbonated soft drinks, fruit juices, sports drinks, energy drinks and vitamin waters, sweetened ice tea (all these beverages are consumed in large volumes in urban areas of our country), fruitades, lemonade, cordials and squashes (the latter two SSBs are popular in the rural areas of South Africa) (Hu & Malik, 2010).

Fruit juice is also implicated

Fruit juice which is listed as an SSB, is generally regarded as a healthy alternative to all the other SSBs which contain added sugars such as sucrose, fructose or glucose. In fact prior to the publication of the South African Labelling Regulations in 2010, most fruit juice containers bore the proud message “No added sugar”.

This is of course misleading because even if a fruit juice does not contain any added table sugar or sucrose, it does contain large amounts of sugar derived from the various fruit juices such as apple, orange and pear juice, which are blended to produce modern fruit juice.

Read: The pros and cons of fruit juice for kids

A glass of blended fruit juice will, therefore, contain plenty of fructose, and as early as 1997 research with children in the USA by Dennison and co-workers indicated that obesity was nearly twice as common among children who consumed fruit juice, than among the children who did not have a glass or more of fruit juice a day.

In addition, 42% of the children consuming fruit juice were found to be stunted, whereas only 14% of those not drinking fruit juice suffered from poor growth.

The latter finding was attributed to the fact that fruit juice has in many cases replaced milk, which has a high nutrient density, in our children’s diets (Dennison et al, 1997).

Tips for Moms

Mothers should preferably give infants and young children clean, safe water to drink rather than fruit juice if they are thirsty.

If you are unsure if the water in your area is clean and safe, boil the water and let it cool down before giving it to your children. Keep in mind that all infants should, if possible, be exclusively breastfed to the age of at least 6 months.

If you include fruit juice in the diet of your older children, then dilute the commercial products by 50% with clean, safe water. If you make your own fruit juice with a liquidiser, also dilute the juice with water or milk, or mix fruit and vegetables if your children enjoy the taste.

Part 2: We consider the latest findings on fructose and how it may or may not affect our metabolism.

DIETDOC© Text copyright: Dr I V van Heerden

Read more:

Part 2: The fructose controversy continues
Ask DietDoc questions about diet and nutrition
It's a fact: fat forms faster with fructose

References: (Dennison et al, 1997. Pediatrics, 99(1):15-22; Department of Health (DOH). 2010. Regulations Relating to the Labelling & Advertising of Foodstuffs. No. R. 146, Foodstuffs, Cosmetics & Disinfectants Act, 1972 (Act 54 of 1972). 1 March 2010. Government Gazette, Pretoria; Grant et al. 1998. J Orthomol Med, 13(2):1-10; Hu & Malik. 2010. Physiol Behav, Feb 6 [Epub]; Tappy & Lê. 2010. Physiol Rev, 90:23-46.)

Image: Shutterstock

Dr Ingrid van Heerden is a registered dietician and holds a doctoral degree in Nutrition and Biochemistry. She believes that "we are what we eat" and offers free nutrition and weight loss advice via her DietDoc service on Health24.com. Read more of her articles.

 
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