The Link Between Sugar And Aging
Is Time’s Sand Sugar? Some top researchers believe that this natural sweetener may not only accelerate ageing but may even cause it.
Poor sugar, everything from excess poundage to diabetes has been blamed for most. We may now have to add one more cause of concern to that long list. A sudden sugar rush in the bloodstream can speed up the process of ageing.
At Rockefeller University in New York City, where Anthony Cerami, PhD and his colleagues are still pursuing the role of sugar in the ageing process, the earliest suspicions surfaced about 15 years ago when work on sugar ageing link started in a medical biochemistry lab.
It was Cerami who first noticed that in human cells, particularly as they age, the same chemical process that makes a streak toughen and turn down during cooling-a spontaneous reaction between sugar and protein called the “browning reaction”-happens. Nonetheless, clearance to market a medication intended to stop the reaction maybe two or three years away. Over time, it can help resolve several age-related problems, ranging from wrinkles and cataracts to certain cancers.
According to Cerami, sugar is one of the culprits that brought the cycle back on track again. Glucose is the basic source of energy for human beings, the substance in which our cells are constantly bathed all our life. The bulk of the food we eat is broken down into sugars and glucose. To explain how glucose can help trigger the ageing issue Cerami looked at how an excess of this sugar behaves in diabetes, as diabetics tend to suffer age-related complications-such as atherosclerosis, cataracts and joint rigidity-much sooner than most people.
Speeding up the ageing
When glucose enters the bloodstream from the intestine, the same is taken up by cells and used as fuel; the rest is stored in the liver and muscles as glycogen, or converted into fat and stored in fat cells until it is needed by the body. In normal circumstances, glucose levels in the blood held by the hormone insulin relatively stable. Diabetes results from a shortage of (or inability to sue) insulin that allows too much glucose to build up in the bloodstream, left unchecked, this would be a death sentence, but that insulin therapy and a carefully controlled diet can, of course, be treated. Nonetheless, even with such medication ageing issues occur sooner.
Cerami and then colleague Ronald J. Koenig found that protein molecules, which are part of the structure of all cells, can be severely affected by the elevated level of glucose in the blood of diabetics. A small number of glucose molecules combine with some of the protein molecules to form “advanced end products of glycosylation,” or ages, over a period of a week to months. (This, in fact, is the browning reaction.) In turn, the AGE particles act as a glue, sticking together some of the other protein molecules in a rigid lattice work pattern called cross-linking. In this way, as protein clumps together, they can clog arteries; block vision, damage to the kidneys and lungs-conditions frequently related to ageing. Cerami saw that glucose could also have destructive potential in non-diabetic bodies. Since glucose-affected proteins play a role in age-related diseases for which the diabetic is at risk early in life, when they happen later, they may play a role in the same illness.
The Stifling Effect of Sugar
Cerami started to analyse the longer-lived proteins from non-diabetics for signs of the cycle. Among these proteins are those which make up the eye lens. When Cerami soaked these crystalline proteins in a solution of glucose, the mixture turned opaque (similar to a cataract lens) and the proteins clumped together. It was again the browning reaction and it led Cerami to conclude that with the aid of glucose, cataracts are produced.
Preliminary research from several U.S. and UK centres appears to confirm the link between sugar and contracts and skin ageing.
Epidemiologist Paul F. Jacques, at the USDA’s Human Nutrition Research Center on Again in Boston, has shown in preliminary studies that galactose, derived from sugar in milk, may play a role in cataract development. By itself, galactose is destructive to the eye’s lens, but it is usually metabolised by the enzyme very quickly. Jacques found this conversion process is slowed in people who are deficient in this enzyme, eventually causing cataracts.
Further links to sugar ageing come from collagen research carried out by Cerami. The most abundant protein in the human body is collagen. It is present in the skin and all the connective tissues, and it helps to “bury” cells. As collagen grows old, it gets stiff-just as we do. Cerami began, incubating the tendon fibres of young rats in various sugar solutions to see if glucose could induce collagen cross-linking. It did and when stretched, the tendon fibres stiffened and broke more easily. Due to the glucose, the tendon fibres of young rats became more similar to those of older rats. The glucose protein reaction had intensified the ageing process, once again.
Vincent M. Monnier, associate professor of pathology at Case Western Reserve University in Cleveland, reinforced the results of Cerami. Monnier found that centuries-olds are loaded with as much as ten times more sugar, children suggesting that sugar actually plays a key role in ageing.
Other potential links to ageing
Ceremi thinks that glucose-hardened collagen can trap cholesterol on blood vase walls, causing atherosclerosis, or artery hardening. And he and laboratory co-worker Richard Bucala have recently begun to explore the possibility that glucose may trigger genetic mutations that can lead to cancer by interacting with DNA.
“The whole topic of increased cancer incidence with age has fascinated me,” Cerami says. It was plausible that AGEs could accumulate on DNA, leading to a genetic material alteration. Consequently damaged cells may not be able to repair themselves or replicate properly. Glucose-induced mutations may also affect the immune system, weakening its ability to keep cancer cells in check. Cerami and other researchers discovered that tat AGEs can indeed cause bacterial DNA mutations. Next on the research agenda is testing cultured mammalian cells to see if the same genetic material changes occur.
What can be done to prevent the body’s browning reaction from destruction? One tentative suggestion is to limit sugar intake in the diet. (Nutritionally, that is not an issue). But since the body ultimately converts almost all the food into sugar, can this really be effective? The research is hardly conclusive; it may still be, some scholars say.
British researchers Anna Furth, Open University biologist, and John Harding, Oxford University Department of Ophthalmology, suggest that heavy sugar snaking can adversely affect even non-diabetic individuals. When we take in the sugar content of a candy bar, the blood glucose level rises dramatically, and as insulin fails to cope with it. A sudden rush of glucose in the bloodstream (whether from the candy bar or from a glass of orange juice-remember, fruits contain fructose, which is, of course, sugar!) starts the browning reaction that causes the protein to cross in.
The researchers believe that aspirin and ibuprofen can help protect protein molecules from marauding glucose based on preliminary studies-although it is clearly too early to translate this theory into action. Perhaps one of the most effective ways of protecting you, they say, is to take carbs as part of a balanced meal with protein, fat and fibre and no early-stomach crab snacking.
Following another tack, researchers are theorising that there should be a way to remove the browning reactions end products, AGEs, before they can glue protein in a cross-link. One option, like AGEs, might be to supplement macrophages, immune system scavengers that extract cellular debris. Cerami notes that macrophages are thought to become less effective as people grow older and that AGEs will build up for cleanup in areas that are not easily reached. One long-term hope is a medication to enhance the macrophage removal mechanism.
An even better bet is firstly a drug to avoid the development of AGEs. Cerami and two former colleagues from Rockefeller, Micheal Brownlee and Peter Ulrich, have already created such a drug, called aminoguanidine. Diabetic rat trials have shown it can greatly inhibit AGE formation. At present, amino-guanidine is being tested on human diabetics. Otherwise, trials are underway using a version of skin cream that might retard the effects of ageing. If the results lead to FDA approval, it would take two to three years to market the products.
There are thrilling possibilities, but Cerami has little interest in making people live forever. Instead, he’s concentrating on preventing the growing old complications. “It gets up in the morning and faces a lot of physical issues,” he says, making ageing uncomfortable. “Our work does not aim to let people live to be 400, but to improve the quality of life.”
Avoiding the Sugar Rush
Do some foods end up as glucose more than others? Or the six basic groupings of nutrients that the body needs, water, vitamins and minerals do not convert to glucose. But according to Gail C. Frank, a nutrition professor at Long Beach’s California State University and a spokesperson for the American Dietetic Association, 100 per cent of all carbohydrates (sugar and starches) wind up as blood glucose, along with 59 percent of proteins and 10 percent of fats. So in a sense, it doesn’t matter whether you ingest table sugar (sucrose), fruit sugar (fructose), or starches like those in potatoes or pasta, they are eventually converted into glucose.
But Frank suggests that if you’re trying to avoid the “sudden rush of glucose” that Furth and Harding’s research believes may exacerbate the protein cross associated with ageing, a solid food, like a banana, will be absorbed into the bloodstream much slower than a liquid, like a glass of orange juice. In addition, she notes that sugars eaten by them (e.g. hard candies) are absorbed faster than starches taken alone, since starch’s chemical structure is much more complex.
Your best anti-ageing bet can be to make a habit of eating sugars and starches as part of a full meal that includes protein, fat and fibre in particular. A glass of orange juice on an empty stomach becomes glucose in the bloodstream in as little as a minute; while it takes several hours to digest a nutrient-balanced meal by prolonging glucose absorption.