Fructose - Friend or Foe?
By Monica Codevilla
Monicas bio: Monica is a Health Consultant with 7 years experience in her field. She is currently completing a BSc Nutritional Therapy (CNELM), and writes about health products for Fresh Earth Food Store.
There seems to be an awful lot of news in the media about Fructose, with controversy surrounding it's long term effects on health. Some proponents believe and swear that it is harmless in the doses that the average population consume it in, while others believe it is a toxin that should be banned by the FDA (Food and Drug Administration). There are always two sides to every story, but one hopes that science is clearcut enough to have unequivocally identified which side is right and which side is wrong.
What is fructose?
Fructose is a simple carbohydrate that occurs naturally in fruit, vegetables, honey, and agave syrup. Crystalline fructose is also commercially available, either derived from corn, or from sucrose (table sugar) which is 50-50 fructose and glucose.
How is fructose made? Through the addition of enzymes to corn starch or sucrose, fructose is separated out, and then crystallised or dried, and milled to produce a pure white granular sweetener (1).
High fructose corn syrup (HFCS) is another source of fructose. It has a similar composition to sucrose, but is manufactured to contain varying ratios of fructose to glucose. Most commercial foods containing HFCS are said to have 55% fructose to 45% glucose (2), however some fizzy drinks contain up to 65% fructose as VHFCS (Very High Fructose Corn Syrup) (3).
Both HFCS and crystalline fructose are found in sauces, biscuits, cereals, beverages, sweets, and fruit flavoured yoghurt. Crystalline fructose can be purchased from health food stores, and some diet specialists recommend it as a healthier choice than sucrose.
Our friend, Fructose, replacing sucrose in the kitchen and in many foods:
In the late 1970s HFCS came to the market from Japan at a significantly lower price than sucrose, and today, both HFCS and crystalline fructose are being added to an array of different foodstuffs. This commercial movement was reinforced by improved texture, taste and stability found in foods that fructose was added to (4). Fructose is also 1.2 times sweeter than sugar, lower in calories, and doesn't disrupt blood sugar levels like glucose does (5).With all that sweetness and less guilt, crystalline fructose is being added into some diabetic as well as weight loss snacks and drinks.
Fructose is low on the Glycemic Index
The Glycaemic Index (GI) compares how different foods influence glucose levels in the blood stream. Pure glucose has the biggest and fastest effect on blood sugar levels with a GI of 100, and the GI of all other carbohydrate foods are set relative to this value. Fructose has a GI of 20, demonstrating only a slight increase in blood sugar levels, whereas sucrose has a GI of 59.
Foods with a GI over 50 are said to have a high GI, which causes blood sugar imbalances. Blood sugar imbalances can cause energy highs and lows, mood swings, cravings and compromised weight control. Long term, it has been linked to diabetes and heart disease (5).
Our foe, Fructose, being shunned from our tables:
It is easy to get lost in the plethora of heated opinions about the safety of fructose, but the latest research seems to overshadow what was previously considered a healthy option. In “Sugar: The Bitter Truth”, Robert H. Lustig, MD, UCSF Professor of Paediatrics in the Division of Endocrinology, says that “Fructose is a poison” as he links the increased consumption of fructose to growing obesity rates and Type 2 Diabetes throughout the world (2).
Various studies are currently defining links between high fructose diets and Syndrome X (6). Syndrome X is a group of unhealthy markers, such as high levels of LDL (“bad” cholesterol) and low levels of HDL (“good” cholesterol), intra-abdominal fat, and high levels of uric acid. These markers are signs of insulin resistance.
Insulin Resistance occurs when the hormone, insulin, becomes less effective at moving glucose from the blood stream into cells in order to lower blood sugar levels.
In one fructose feeding study (7), obese and overweight people were put on a high fructose or a high glucose diet. When the two groups were compared, the high fructose group had higher levels of weight gain around the mid section (notably of internal organs), developed fatty livers, and levels of LDL increased, while insulin sensitivity decreased.
The increase in weight gain is somewhat surprising, given the fact that fructose has long been hailed a low calorie sweetener. One reason for this weight gain may be that the body does not register fructose as a usable source of energy, and therefore doesn't release the satiety hormone, leptin (8), resulting in overeating.
Studies show that fructose metabolism increases uric acid levels (9), and the NHS (British National Health Service) now recommends fructose avoidance for those suffering from Gout (10). Gout is a painful condition caused by the build up of uric acid in joints.
All these health disturbances come as less of a surprise when one considers that the structure of fructose is different to glucose (11), and the body uses a completely different metabolic pathway in order to remove it. Glucose is the primary source of fuel in the body and can be metabolised anywhere, whereas fructose can only be broken down in the liver. Overloading the liver with this isolated compound leads to the various signs of Syndrome X.
Conclusion:
Fructose can be found listed on many convenience foods labels, as part of the glucose-fructose mix in HFCS, Isoglucose, maize/corn syrup, glucose/fructose syrup, or the more concentrated form called crystalline fructose.
We also consume fructose from fruit and some vegetables as part of a healthy and well balanced diet. Fruit contains fibre, which bulks up the stool, slows down the absorption of sugars, and keeps you fuller for longer. Fruit is also full of other vitamins, minerals and phytonutrients that support metabolic functions in the body.
Fructose in fruit and vegetables is always accompanied by glucose (in more or less equal amounts)(12) which tempers the ill effects of fructose. An interesting study showed that moderate amounts of fructose, up to 50g per day, actually show no adverse effects, and may actually improve blood sugar levels(13).
More research is needed, as it is known that the ill effects associated with fructose consumption are aggravated by length of exposure (i.e. days or months), age, and prior tendency toward insulin sensitivity (14).
10 teaspoons of crystalline fructose = 50g, or 20 teaspoons of sugar, or 2 ½ cans of cola [1 cola = 40g HFCS or VHFCS) http://www.coca-cola.co.uk/brands/coca-cola.html.)
What should one do about it?
Over exposure to fructose from convenience food products (15), as well as refined crystalline fructose, is not good for ones health. Research seems to be weighing one sugar up against the other. Sucrose has also been shown to cause disease in the body, but does appear less harmful than fructose. Some research argues that, despite its' high fructose content, natural honey (16) might be a healthier option than sucrose or pure fructose.
There is plenty of proof that sweet excesses of any kind are not a good thing. Robert. H. Lustig,. M.D. sums up his presentation, Sugar:The Bitter Truth (2), by advising people to “eliminate sugary drinks and foods, and to eat fibre rich carbohydrates”, as well as to do more physical activities, which will help burn off excess sugars that would otherwise cause disease in the body.
References:
(1)Calorie Control Council, (2010) Facts about Fructose (online) Available at: [Accessed 19 April 2011]
(2)Robert H. Lustig, MD, (2009) Sugar: The Bitter Truth (online video) http://www.youtube.com/watch?v=dBnniua6-oM (Accessed 21 April 2011) Series: UCSF Mini Medical School for the Public [7/2009] [Health and Medicine] [Show ID: 16717] )
(3) Kaplan K.,(2010). High-fructose corn syrup in soda has much more fructose than advertised, study finds. In: Los Angeles Times. (Online) Available at: [Accessed 5 May 2011].
(5) Haynes, A,. Glycemic Index of Common Foods. The Nutrition Clinic Ltd. [Incomplete].
(6) Elliott S.S., et al.,(2002). Fructose, weight gain, and the insulin resistance syndrome. Am J Clin Nutr. 76(5):911-922.
(7) Stanhope K. L., et al.,(2009).Consuming fructose-sweetened, not glucose-sweetened, beverages increases visceral adiposity and lipids and decreases insulin sensitivity in overweight/obese humans. J Clin Invest.119(5):1322–1334.
(8) Angelopoulos T. J.,et al., (2009)The Effect of High-Fructose Corn Syrup Consumption on Triglycerides and Uric Acid. J. Nutr. 139(6): 1242S-1245S.
(9) Choi H.K., MD, DrPH.,et al.,(2010) Fructose-Rich Beverages and Risk of Gout in Women. JAMA. 304(20):2270-2278.
(10) NHS, (2010) Sweet drinks and gout risk studied (online) http://www.nhs.uk/news/2010/11november/pages/sweet-drinks-and-gout-risk-for-women.aspx [Accessed 14 April 2011]
(11) Dr Ken Gillman comments in The Skeptic. “More Sweetness” - Pg 54 (online) Available at: [Accessed 20 April 2011]
(12)White J.S.,et al., (2009) Misconceptions about High-Fructose Corn Syrup: Is It Uniquely Responsible for Obesity, Reactive Dicarbonyl Compounds, and Advanced Glycation Endproducts?.J. Nutr. 139 no. 6 : 1219S-1227S.
(13)Livesey G., Taylor H., (2008). Fructose consumption and consequences for glycation, plasma triacylglycerol, and body weight: meta-analyses and meta-regression models of intervention studies. Am J Clin Nutr. 88:1419-1437.
(14) Stanhope K. L., Havel P. J.,(2009). Fructose Consumption: Considerations for Future Research on Its Effects on Adipose Distribution, Lipid Metabolism, and Insulin Sensitivity in Humans. J. Nutr. 139:1236S-1241S.
(15) University of Florida, (2007 ). Too much fructose could leave dieters sugar shocked. [online] Available at: [Accessed 26 April 2011].
(16) Busserolles J., et al.,(2002). Substituting Honey for Refined Carbohydrates Protects Rats from Hypertriglyceridemic and Prooxidative Effects of Fructose. J. Nutr. 132:3379-3382.
