Sugar and starch drive obesity and disease

Dr Paul Clayton’s Health Newsletter March 2014

“Added refined sugars and starches in the daily diet are undoubtedly contributing to obesity and disease.”

Sugar has been getting a bad press lately, with a series of books and articles telling us how it contributes to problems with insulin, weight gain and diabetes. I go along with some of that, but would expand the dietary definition of sugars to include starch (high-starch foods include white flour, rice and pasta, potatoes).

From the body’s perspective, sugar and starch are pretty much the same thing; all these ‘digestible carbohydrates’ end up pouring glucose into the blood. There is good evidence that cutting down on both sugars and starches improves blood glucose management (Volek & Feinman ’05, Accurso et al ‘08), as does exercise, which acts on the other side of the equation by increasing the rate at which glucose is removed from the blood (Knowler et al ’02 &’05, Lutsey et al ’07).

Unsurprisingly the sugar industry is punching back, and trying to persuade us that their product is not as pure, white and deadly as it has been painted. AB Sugar, part of Associated British Foods and the world’s second-largest producer of sugar, recently went public to claim that sugar cannot be a leading cause of obesity because over the last 3 years sugar consumption has fallen by 9%, even as obesity rates continued to rise. This claim is, of course, baloney.

Nobody ever said that sugar was the only cause of obesity, or that our outlandishly inactive lifestyles were not also to blame; but in a situation where sugar still accounts for an average 12.3% of total caloric intake in the UK, and too many of us are living urbanised and sedentary lives, it is undoubtedly contributing to obesity and disease. These are empty calories, which modern malnourished and under-exercised folk can ill afford to indulge in, as shown in a group of new studies which identify a link between excessive sugar consumption, heart disease and cancer.

One study of 43,000 adults found a strong correlation between increasing consumption of added sugars in drinks, snacks and sweets, and increased risks of dying from heart disease (Yang et al ’14). Those who consumed 10 – 25% of calories from added sugars had a 30% higher risk of dying from heart disease compared to those whose consumption of sugar accounted for less than 10% of total calories. Those with over 25% of calories from added sugars – about 10% of the sample – were nearly three times as likely to die from heart disease.

Next, the cancer link. One recent study at the University of Minnesota of 23,000 post-menopausal women found that those who consumed sugar-sweetened drinks were more likely to develop the most common type of endometrial cancer compared with women who did not (Inoue-Choi et al ’13); with the highest intake group reporting a 78% increase in risk. A study from Aberdeen University found that diets containing more snack foods high in sugars and fats were linked to an increased risk of colorectal cancer (Theodoratou et al ’14).

Does excessive sugar itself increase the risk of clinical cancer, or is a high intake of sugar, as the sugar companies maintain, simply a marker for an unhealthy lifestyle and a poor diet in general? It is always difficult to untangle the numerous confounding variables, but in all likelihood both of these angles are true.

It has long been known that cancer cells like glucose, and are good at soaking it up to utilise as an energy source. It is known, too, that high sugar intakes stimulate the release in the body of insulin and insulin growth factors, which drive cancer growth. Very recently a new link in the chain was revealed: a high intake of sugar switches on a gene called P53, which also speeds up cancer growth (Rodriguez et al ’12). Being insufficiently physically active makes matters worse in several different ways, involving such links as AMP-K and M-TOR (Faubert et al ’14). At the same time, if you are only eating around 2000 calories per day, and too many of your calories are empty ones, then you will be seriously depleted in many of the cancer-protective compounds that occur in a healthy diet; and you will almost certainly be experiencing chronic inflammation, which is another cancer enhancer.

The link between high sugar intake and heart disease is equally complex. A diet high in sugar would be expected to damage blood vessels via glycation reactions. It is also likely to be deficient in cardio-protectors such as polyphenols and omega 3s, and high in the pro-inflammatory compounds that are formed in so many processed foods.
The intense non-sugar sweeteners are hugely divisive, but the more we know about the problems with sugar and starch, the better they look, especially for sedentary folks. Saccharine, aspartame, sucralose et al have all gone through extensive safety screening; the negative research people quote is so poorly done as to be meaningless, and much of it was funded by – you guessed it – the sugar industry.

Accurso A, et al Dietary carbohydrate restriction in type 2 diabetes mellitus and metabolic syndrome. Nutr Metab(Lond)2008 Apr 8;5(1):9

Faubert B, et al. TheAMP-activated(AMPK) and: Cancer. 2014 Jan 28. pii: S0304-3835(14)00054-8

Inoue-Choi M,al. Sugar … endometrial cancer in postmenopausal women. Cancer Epidemiol Biomarkers Prev.Dec;22(12):2384-94.

Knowler WC, et al. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med 346:393-403, 2002

Knowler WC, et al; Prevention of type 2 diabetes with troglitazone in the Diabetes Prevention Program. Diabetes. 2005 Apr;54(4):1150-6.

Lutsey PL, et al. Dietary Intake and Metabolic Syndrome. Atherosclerosis Risk Study. Circulation 2008 Feb 12;117(6):754-61

Rodriguez,al. Dietary downregulation of mutant p53 levels via glucose restriction … Cell Cycle.Dec 1;11(23):4436-46.

Theodoratou, et al Associations between dietary and lifestyle risk factors and colorectal cancer … Eur J Cancer Prev. 2014 Jan;23(1):8-17.

Volek JS, Feinman RD. Carbohydrate restriction improves the features of Metabolic Syndrome. Nutr Metab (Lond). 2005 Nov 16;2:31.

Yang Q,et al. Added Sugar … and Cardiovascular Diseases Mortality… JAMA Intern Med.2014 Feb 3. doi:10.1001/jamainternmed.2013.13563