New research findings into traditional supplemental ingredients are driving new applications for diabetes health. Food formulators are taking note, and incorporating GRAS-approved ingredients into their offerings, and also utilising better-for-you ingredients. Todd Runestad surveys the changing diabetes landscape
Diabetes is closely linked to, in the early stage, metabolic syndrome, and on the later stage, obesity. Indeed, the latter two are so thoroughly linked that their combination has given rise to a new quasi-medical term: diabesity.
Diabetes itself is a group of diseases marked by high levels of blood glucose resulting from defects in insulin production, insulin action or both. As the need for insulin rises, the pancreas gradually loses its ability to produce it. Diabetes can lead to serious complications, from high blood pressure to kidney disease, stroke and premature death, but people with diabetes can take steps to control the disease and lower the risk of complications.
The opportunities this presents to food and supplements manufacturers are clear. And raw-materials suppliers are rising to the occasion to help with the reformulation, integration and introduction of new, novel and better-for-you ingredients to improve the healthiness profile of finished goods.
Alpha-lipoic acid: With metabolic syndrome on everyone's lips, it's notable that lipoic acid has been shown to benefit four of the five symptoms of the condition: excess weight, insulin resistance, atherogenic dyslipidaemia (specifically, low HDL cholesterol and elevated triglycerides), and high blood pressure.1 This makes it an excellent supplement for those wishing to prevent the occurrence of diabetes. But what of full-blown diabetes? For 30 years German doctors have prescribed 'the universal antioxidant' to patients with diabetic neuropathy. It has been shown to improve insulin action and to increase insulin-mediated glucose disposal — but mostly after parenteral administration.2
One recent study aimed to check that state of affairs. In a double-blind, placebo-controlled trial, 24 overweight middle-aged subjects were given 600mg alpha-lipoic acid, or placebo, twice daily for four weeks. Insulin sensitivity increased significantly — glucose disposal rate increased from about 3.2 to 5.9mg/kg/minute. The insulin sensitivity index also significantly increased, from about 4.7 to 7.7.3
In the past year, a few case studies have been published about a correlation between alpha-lipoic acid and what is called insulin autoimmune syndrome, a rare disease characterised by low blood-sugar levels and auto-antibodies to insulin.4 Although rare, and reported in only case studies, it probably bears paying some attention to.
Bitter melon (Momordica charantia): Locally known in Bangladesh as the bitter vegetable called karolla, it was first studied in 1999 in Bangladesh on 100 human subjects with moderate diabetes. Drinking an aqueous homogenised suspension of the vegetable pulp led to a significant reduction of both fasting and post-prandial serum glucose levels in 86 per cent of cases, while an additional five per cent showed lowering of only fasting serum-glucose levels.5
A class of chemicals called cucurbitane triterpinoids is the characteristic constituents of M charantia. These were first fractionated from an extract of bitter-melon dried gourds in 2006, by Japanese researchers.6 That kicked off a flurry of very recent animal research into its ability to improve glucose and insulin tolerance. In March 2008, Chinese researchers identified them as mediating glucose uptake and fatty acid oxidation in cells. Furthermore, the momordicosides enhanced fatty-acid oxidation and glucose disposal during glucose-tolerance tests in both insulin-sensitive as well as insulin-resistant mice. Several of the tested compounds had effects comparable to those of insulin.7
In April 2008, researchers from India reported that bitter-gourd extract improves insulin sensitivity, glucose tolerance and insulin signaling in rats induced to insulin resistance by a high-fat diet. Benefits in the 10-week study were seen after only two weeks.8
Cinnamon: Unlike bitter melon, cinnamon tastes good! Although used traditionally as a spice for foods, it has found most of its success from a health-benefit standpoint in the supplements world. There are two types of cinnamon typically found on the market: Cinnamomum zeylanicum nees or C cassia blume. The latter is the focus of scientific research, which finds it improves insulin's action.
In a 2003 animal study, Chinese researchers found cinnamon extracts improve the metabolic action of insulin and help prevent insulin resistance in part by increasing glucose uptake into cells and enhancing the insulin-signaling pathway in muscle.9
Cinnamon's active ingredient appears to be double-linked polyphenol Type-A Polymers. These compounds increase insulin-dependent glucose metabolism in vitro by 20-fold, and mimic insulin.10,11 They also have been shown to reduce blood pressure — making cinnamon effective in preventing some symptoms of metabolic syndrome.
In a human study with 60 men and women with diabetes, those taking 1, 3 or 6g/day cinnamon for 40 days experienced decreases in fasting glucose levels of 18-29 per cent.12 A human study using a lower dose, 500mg/day for 12 weeks, gave 83 per cent of subjects an average eight per cent decrease in fasting blood-sugar levels.13
The active components in cinnamon are not destroyed by heat, so cinnamon could certainly play an enhanced role in processed foods — and even cinnamon sticks added to tea can be beneficial.
HCA: In recent years, Garcinia cambogia has been promoted for weight loss due to various possible effects it may have on the body. First, it is believed to interfere with an enzyme needed to store fat, possibly causing more fat from foods to be eliminated from the body. In addition, it may cause the body to use existing fat stores for energy during prolonged exercise. Ordinarily, carbohydrates are used before fats during exercise. In animal studies, hydroxycitric acid (HCA), a major component of Garcinia cambogia, also seemed to reduce appetite by raising the amount of serotonin in the body. In a 2007 animal study, HCA not only reduced food intake and body-weight gain in obese rats, but it also decreased inflammation, oxidative stress and insulin resistance compared to controls.14
Chromium: This mineral is at the heart of a biologically active complex called Glucose Tolerance Factor or 'GTF,' which is responsible for increasing the action of insulin in the body. Originally applied solely to supplements, it is now finding a home in bars, beverages and even chewing gums.
The two primary forms of chromium on the market are chromium picolinate and niacin-bound chromium polynicotinate. Both have research to back their efficacy.
In a 2006 review, researchers noted that 13 of 15 human clinical trials, including 11 randomised, controlled studies involving more than 1,500 subjects in the chromium-picolinate group, reported significant improvement in at least one outcome of glycaemic control. These areas included reduced blood glucose, insulin, cholesterol and triglyceride levels, and reduced requirements for hypoglycaemic medications.15
In a 2004 double-blind, placebo-controlled trial on niacin-bound chromium, subjects receiving 300mcg/day chromium for three months experienced significantly lowered fasting blood-glucose levels, and modest decreases in triglyceride levels as well as glycosylated haemoglobin, a measure of long-term glucose control.16
Combining chromium with other nutrients is also a developing trend. In 2002, researchers combined niacin-bound chromium with a water-soluble fraction of maitake mushroom and HCA. Diabetic rats receiving the combination had significantly reduced body weight, blood pressure and fasting blood-glucose levels.17
Chromium picolinate was combined with biotin, a water-soluble B-complex vitamin, in a 2006 human clinical trial with 43 patients with impaired glycaemic control. In this double-blind, placebo-controlled trial, those receiving 600mcg/day chromium with 2mg/day biotin for four weeks had a 9.7 per cent reduction in glucose during the two-hour oral glucose-tolerance tests, compared to a 5.1 per cent increase in the control group.18
The combination of chromium picolinate and biotin has been patented as Diachrome. In a 2005 analysis, economists at Widener University in Pennsylvania concluded that using this combination among the 1.17 million newly diagnosed patients with type-2 diabetes each year could deliver a lifetime cost savings of $42 billion, or $36,000 per patient.19
As well as chromium, the trace mineral selenium has been shown to influence blood-insulin levels and insulin effectiveness. Low levels of zinc are associated with diabetes and cardiovascular disease. And vanadium compounds have been shown to have insulinlike effects.20 Combining these trace minerals with chromium can offer intriguing intellectual-property opportunities for savvy developers.
Fibre: The indigestible part of plants is known as fibre. Soluble fibres such as psyllium, flax, gums and oats form gels in the intestine and slow the rate of nutrient absorption, which helps reduce blood-sugar levels after meals are consumed. Insoluble fibres from whole grains increase bulk and slow down the movement of matter through the bowel. Both fibre types prolong gastric emptying and bind cholesterol to limit its absorption. Dietary fibre also inhibits the activity of alpha-amylase and postpones the release of glucose from starch.21
Water-soluble fibre, such as oat bran, helps balance blood sugar. Researchers tested post-meal glucose and insulin effects of whole-kernel rye bread, whole-meal rye bread containing oat beta-glucan concentrate, dark durum wheat pasta and white bread made from white wheat flour. Each product provided 50g carbohydrates. Upon eating, 10 men and 10 women with normal glucose tolerance had their fasting and eight post-meal blood samples collected at 15-30 minute intervals for three hours to determine levels of blood glucose, glucose-dependent insulinotropic polypeptide (GIP), glucagons-like peptide 1 (GLP-1), and serum insulin.
Glucose responses and the rate of gastric emptying after consumption of the two rye breads and pasta did not differ from the white wheat bread (with the exception of GLP-1 response to the rye bread containing oat beta-glucan). However, GIP and GLP-1 responses, which both stimulate insulin response, and insulin were lower after eating rye breads and pasta than white wheat bread. Researchers concluded the insulin response is determined more from the form of food rather than the amount of fibre or type of cereal in the food.22
A further study measured the effects of fibre enrichment of pasta and fat content on gastric emptying, GLP-1, glucose and insulin responses to a meal. Researchers added 1.7g psyllium, which was enough fibre to qualify for a US FDA claim for reduced cholesterol and risk of coronary heart disease. The psyllium-enriched pasta had no significant effect on gastric emptying or the area under the curve for GLP-1, insulin or glucose compared with the control pasta. However, when they added 30g sunflower oil and 3g sodium propionate, the 10 subjects experienced significant reductions in gastric emptying, an increase in GLP-1, and reduced glucose and insulin concentrations.23
Resistant starch: Recently, it has become accepted that there are not merely two forms of fibre, soluble and insoluble. A third type — resistant starch — has come on to the scene. These so-called nonglycaemic carbohydrates resist digestion in the small intestine, are fermented like some dietary fibres to provide long-term energy, and can increase insulin sensitivity in healthy people. In one study, 10 healthy people ate two identical meals, but one contained 60g resistant starch (Novelose 260, National Starch). The following morning, a fibre-free meal tolerance test was taken and postprandial insulin sensitivity assessed. Results showed that those eating the resistant starch meal the day before experienced lower postprandial blood glucose and insulin, with a higher insulin sensitivity the next day.24
In sum, seven published studies have shown beneficial effects of natural R-2 resistant starch on glucose and insulin response. When substituted for flour, it lowers the glycaemic response of foods in a dose-dependent manner.25
Beta-glucan: In 2006, researchers added a variable to the resistant-starch story by including different quantities of beta-glucan to muffins. While beta-glucan decreased glucose and insulin under the curve between 17 and 33 per cent, and resistant starch's numbers were 24 and 38 per cent, when both functional ingredients were combined, the result was 33 and 59 per cent for glucose and insulin, respectively.26
Before formulators go out and begin adding beta-glucan to meals, they would do well to heed the results of a recent test carried out in the Department of Food Science & Microbiology at the University of Milan in Italy.27 Researchers there added beta-glucan to barley flour or whole-wheat flour and made cookies and crackers. In general, they found that cookies responded better to the addition of barley fibre than crackers, highlighting the complexity of the effect barley fibre may exert when added to different food products to address glucose metabolism and diabetes.
Salba: This novel grain from Argentina (Salvia hispanica) has been introduced into the market, and boasts high quantities of fibre and the omega-3 alpha-linolenic acid as well as protein, calcium, magnesium, iron and antioxidants. More to the point, it is showing benefit for diabetics.
In a study published in November 2007, researchers in Toronto (the town that made the Glycaemic Index famous) gave 20 diabetics either 37g/day Salba or wheat bran for 12 weeks while maintaining their conventional diabetes therapies. Compared with the control group, the Salba group experienced reduced systolic blood pressure by 6.3mmHg and C-reactive protein levels, a marker of inflammation.28
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