Sunday, June 14, 2015

Wrongly Convicted: High-Fructose Corn Syrup

The use of high-fructose corn syrup (HFCS) has become the punching bag of those who are legitimately concerned about the ubiquitous practice of adding large quantities of refined sugar to processed foods, cereals, and to manufactured beverages of all kinds.  However, focusing on the perils associated with the use of HFCS while tacitly or explicitly approving the addition of more ‘natural’ sugars to food and beverages is a misrepresentation of the link between the addition of refined sugars to our diet and the current epidemic of obesity and diabetes.  The fact is that HFCS and table sugar (sucrose) are identical in their chemical composition and there is no evidence that they have differential effects on the rate of obesity or diabetes. It is the total amount of refined sugar in the diet that is important not whether it comes from sugar cane or beets (sucrose), or from corn (HFCS).
Sucrose, or ordinary table sugar, is chemically classed as a disaccharide in which each molecule is formed by the combination of two simple sugar molecules, one glucose and one fructose.  Corn syrup is derived from corn starch and the sugar it contains is 100% glucose which is not as sweet as fructose.  To produce a realistic substitute for table sugar, corn syrup is modified to a high-fructose corn syrup that has the same percentage of fructose and level of sweetness as table sugar.

The most ardent critics of the practices of the food industry agree that there are no fundamental chemical differences between sucrose and HFCS.  However, it is certain that the introduction of HFCS as an additive to food and beverages has facilitated a large increase in the total amount of refined sugars we consume with its concomitant negative effects on health.  The damage being wrought by HFCS is because its often low cost relative to cane sugar has made it possible for food producers to increase the amount of added sugar in their products without having to implement the cost increases that might impact consumer demand.  Although food producers, with the help of HFCS, have been able to give consumers the sweetness they seem to crave without requiring them to pay the price, the ultimate cost to the consumers in terms of poor health is likely to be much higher than they bargained for.

Saturday, April 18, 2015

No Free Lunch: the Story of Non-Caloric Artificial Sweetners

Non-caloric artificial sweeteners (NAS) are sugar substitutes used to give sweetness to food and drinks without the inconvenient calories; to those among us with a sweet tooth their unique properties may seem too good to be true. NAS are widely used in processed foods, soft drinks, and diet products.  In the United States, the most commonly used NAS compounds are saccharin (e.g. Sweet N’Low), aspartame (e.g. Nutrasweet), and sucralose (e.g. Splenda), all of which have been approved by the Federal Drug Administration (FDA) which regulates the use of NAS as food additives.  The FDA has also approved three other NAS food additives (neotame, advantame, and acesulfram potassium) and had ‘no objection’ to the use of Stevia, a plant-based sweetener, in foods because it is generally regarded as safe.  Despite the long history of NAS consumption (Stevia has been used as a sweetener for centuries in South America and saccharin was first synthetized in 1879) and the FDA evaluation and approval of specific NAS, there has been a lingering suspicion that their unique properties may indeed be too good to be true.  A scientific paper (1) published in the journal Nature in late 2014 provides indirect evidence that the widespread use of NAS is not good for human health and supports those who are skeptical of the concept of a free lunch.

The authors examined the effect of adding formulations of each of three common NAS (saccharin, sucralose, aspartame) to the diet of mice. The main findings were that the NAS led to abnormal glucose tolerance* in the mice and this was associated with specific changes in the gut flora (microbiota) of these mice. Transfer of the gut flora from the treated to a group of untreated mice (by fecal transplant) led to the development of glucose intolerance in the recipients indicating that the change in the composition of the micobiota led to the abnormal glucose metabolism.  The authors also studied the association between NAS consumption and physical and metabolic measurements in 381 human subjects and found that there was a positive correlation between the amount of NAS they consumed and increases in body weight and blood glucose and in the prevalence of abnormal glucose tolerance.  Finally, they supplemented the diet of seven healthy human volunteers with the maximum acceptable daily dose of NAS recommended by the FDA for a period of seven days and found that four out of seven developed abnormal glucose metabolism in this short period of time.  Although none of the findings in the study provide definitive proof that the regular consumption of NAS in food is an important contributor to the explosion in the prevalence of diabetes and obesity in the economically advantaged parts of the world, the data should give those who regularly reach for a diet soda a moment of pause.

(1) Suez J et al. Artificial sweeteners induce glucose intolerance by altering the gut microbiota.  Nature. 2014 Oct 9;514(7521):181-6. doi: 10.1038/nature13793.

*The glucose tolerance test is a method used to assess how the body metabolizes a standard infusion of glucose over a two-hour period. First, the baseline fasting blood glucose is measured then another blood glucose level if measured two hours after the ingestion of a specific amount of glucose (in humans for example, the standard dose of glucose used for the test is 75 gm).  The principle on which the test is based is that normal metabolism tightly regulates the increase in blood glucose through the release of insulin which shifts the glucose from the blood stream into the tissues.  Therefore, one can predict the blood glucose two hours after being given a specific amount of glucose and departures from that prediction indicate abnormal glucose tolerance.  For example, in human subjects the blood glucose two hours after ingestion of 75 gm glucose should be less than 140 mg/dL; levels between 140 and 199 mg/dL indicate abnormal glucose tolerance, and levels greater than 199 mg/dL are diagnostic of diabetes.    

Wednesday, April 01, 2015

Emulsifiers in processed food and your health

A recently published paper in the journal Nature (1) suggests that the emulsifiers added to many processed foods can lead to inflammation of the large bowel and to obesity and related diseases such as diabetes. The paper is an account of a research study in which groups of mice were fed one of two common synthetic emulsifiers (carboxymethylcullulose and polysorbate-80) in their drinking water for 12 weeks and then compared with genetically similar mice who over the same time period had been given an identical diet but without the added emulsifiers. The mice who ingested emulsifiers had a profound change in the composition and in the distribution of intestinal bacteria (gut microbiota): (i) there were fewer bacterial species overall and a reduction in the numbers of bacterial species commonly associated with good health, and (ii) the distance between the bacteria and the cells lining the bowel, normally covered by a layer of protective mucus, was reduced by 50%. Associated with these changes in the gut microbiota, the emulsifier-treated mice had a higher prevalence of inflammation of the large bowel and of obesity, an increased fasting blood glucose, and an abnormal response to large doses of glucose similar to that found in diabetes. Transfer of the gut microbiota (through fecal transplant) from the emulsifier-treated mice to a group of non-treated mice led to the development of bowel inflammation and obesity in the transplanted group indicating that changes in the microbiome were necessary and sufficient for all the other effects that were observed. The authors of the study suggest that the harmful effect of the emulsifiers was through disrupting the thick layer of mucus that lines the intestine and protects it from intestinal bacteria; damage to the mucus layer would reduce its protective effect making chronic inflammation and associated abnormalities (obesity, diabetes) more likely.

Emulsifiers are used to bind different liquids together (e.g. oil and water) that under normal circumstances would remain separate. Creating an emulsion is a crucial step in the production of many processed foods, and as a consequence, emulsifiers are ubiquitous in the processed food industry that uses 400,000 metric tonnes of synthetic emulsifiers each year in products ranging from ice cream, baked goods, and processed meats to chewing gum. The results of this study discussed above are not comforting to those for whom processed food is a major component of their diet. It is not known how the findings in this study relate to human obesity, dietary choices, and the practices of the food processing industry. However, the results are consistent with the growing conviction that the gut microbiota has an important role in human matabolism, nutrition, and immunity. It is possible that change in gut microbiota that result from changes in diet, particularly the additives in processed food, is a significant contributor to the epidemic of obesity in the United States and in other economically advanced countries.

(1) Chassaing B, Koren O, Goodrich JK, Poole AC, Srinivasan S, Ley RE, Gewirtz AT.Dietary emulsifiers impact the mouse gut microbiota promoting colitis and metabolic syndrome. Nature. 2015 Mar 5;519(7541):92-6