| PDF[?] (Download) | Type 2 DiabetesPhytotherapy | | Date: December 15, 2003 | HC# 040232-246 |
Re:Phytotherapy and Nutrition in Type 2 Diabetes
Walker A, Marakis G. The role of nutrition and phytotherapy in integrative medicine for type 2 diabetes British Journal of Phytotherapy. 5(4):165-175.
This article, given as a talk at a Seminar of the College of Practitioners of Phytotherapy in October, 2000, discusses findings from clinical trials using micronutrients or herbal interventions along with conventional therapies in treating type 2 diabetes and also describes a case history of a diabetic patient the authors saw in private practice. The authors provide a general overview of diabetes, a metabolic defect causing poor glucose metabolism which affects 4% of adults over 65 in the U.K. and 16% of adult immigrants from the Indian subcontinent; nearly 8% of the U.K. drug budget is used for patients with diabetes. Diabetes is on the rise worldwide, a phenomenon blamed by many on increasing consumption of refined foods. Diabetes multiplies risk of cardiovascular disease two-fold in men and three-fold in women, and increases risk of microvascular diseases. Insulin Resistance Syndrome (IRS), often manifested early in type 2 diabetes, is discussed in some detail.
Strategies for better glucose control (Table 5) include weight loss, exercise, diet (elucidated in Table 6), conventional drugs, and herbal medicine. The aim of nutritional therapy is slowing glucose absorption to spare insulin. The Glycemic Index (GI) of some foods, compared with glucose and fructose, is shown in Table 7 of the article. Interestingly, while one management strategy in Table 5 is increased intake of soluble dietary fiber, whole wheat bread has a slightly higher, and therefore less desirable, GI than white bread; diabetics may wish to avoid both and opt for other high-fiber foods. Pasta has a slower glucose-release.
Diabetics are at risk of mineral and vitamin deficiencies due to changes in kidney and gastrointestinal physiology, increased urinary excretion, and reduced intestinal absorption. Chromium, zinc, and magnesium are important in glucose control. While studies of supplementation with these minerals in diabetics have had mixed results (Table 9), the authors conclude that the weight of the evidence suggests that supplementation may be beneficial. Also, diabetics' excretion of water-soluble vitamins, particularly the B vitamins, is high. Studies of B vitamin supplementation in diabetics have found reduced glycated hemoglobin (HbA1c) levels, and evidence of reduced risk of raised plasma homocysteine associated with diabetic neuropathy. Many complications of poor glucose control and the homeostatic aberrations which cause them (Table 3) are underlain by oxidative stress. Studies on the antioxidant vitamins E and C, which reduce atherosclerosis and protein glycation, have mostly been carried out in non-diabetics, but are pertinent to diabetics since the disease increases free-radical damage. In Table 10, a possible supplementation regimen is shown, including selenium and omega-3 fatty acids as well as the micronutrients discussed.
Over 1,000 plants have been used in traditional medicine systems for their hypoglycemic effects (see HCs 020432.235, 071707.181, and 042319.224), but few have been scientifically investigated. Some clinical evidence exists for gymnema (gurmar; Gymnema sylvestre), Asian ginseng (Panax ginseng), bitter melon (bitter gourd, karela; Momordica charantia), fenugreek (Trigonella foenum-graecum), and holy basil (Ocimum tenuiflorum syn. O. sanctum). Others with traditional use and some pharmacological evidence or promising animal studies which may be encountered in western herbal medicine, include goat's rue (Galega officinalis), cinnamon (Cinnamomum verum syn. C. zeylanicum), walnut leaves (Juglans regia), prickly pear (Opuntia ficus-indica), bilberry leaves (Vaccinium myrtillus), agrimony (Agrimonia eupatoria [The article gives the botanical name of A. europea.]), and devil's club (Oplopanax horridus). The authors focus on goat's rue, commonly used by western herbal practitioners although there are no human clinical studies supporting it, and gymnema, an extract of which has had promising results in human studies in India. Other herbs, including hawthorn (Crataegus laevigata syn.C. oxyacantha), ginger (Zingiber officinale), devil's claw (Harpagophytum procumbens), meadowsweet (Filipendula spp.), celery or celeriac (Apium spp.), lignum vitae (Guaiacum officinale), rutin (derived from buckwheat Fagopyrum esculentum), and a 'willow complex' (likely including Salix spp.), were used for particular symptoms in the case history presented. The authors note improved overall well-being early in treatment with micronutrients and herbs, boosting patients' confidence and compliance with necessary long-term lifestyle changes.
In collaboration with the Diabetes Centre of the Royal Berkshire Hospital, the authors participated in clinical studies of micronutrient supplementation. A double-blind, placebo-controlled, cross-over study examined effects of a daily multivitamin and mineral supplement specially formulated for diabetics (Diabetone®, Vitabiotics, Ltd., Wembley, UK) for three months. While outcome measures showed favorable responses to the supplement, none differed significantly from placebo. The authors attribute this to the brief study period. However, they note a significant decrease in anxiety among participants taking the supplement as compared with those taking placebo. Although not the case here, participants in clinical trials often report an improved sense of well-being, regardless of whether they are in the active or placebo arm of a study; this is generally attributed to the 'placebo effect.'
A second trial investigated hypoglycemic effects of a gymnema extract, similar to one used in trials in India, compared with an extract of goat's rue and with a combination of the two herbs. Four groups of 20 non-insulin dependent, diet-controlled type 2 diabetics were recruited and assigned to one of four treatment groups for four months (the fourth group received magnesium citrate daily, equal to 600 mg of elemental Mg). Treatment was double-blind. No significant differences were seen among the groups. However, a promising reduction in triglycerides was shown by the goat's rue group. Study results were incomplete when this paper was published. Some individual participants had significant results. Figure 5 shows results for one volunteer in the combination herb group who requested to continue the treatment after the study. The authors speculate that genetic factors may have influenced the inconsistent results.
The authors' subsequent work has focused on specific zinc and chromium supplementation and on hawthorn supplementation for hypertension. They stress that, while most clinical studies examine one intervention, in practice, multiple interventions are more likely to be successful. They recommend that dietary supplements be used as a foundation treatment for all trials of herbal treatments for diabetes. This would obviate the need for a placebo group, with its ethical questions in a progressive disease, as all participants would probably realize some benefit.
— Mariann Garner-Wizard |