Clinical Briefs
With Comments from Russell H. Greenfield, MD. Dr. Greenfield is Clinical Assistant Professor, School of Medicine, University of North Carolina, Chapel Hill, NC; and Visiting Assistant Professor, University of Arizona, College of Medicine, Tucson, AZ.
Mouthwatering: Acupuncture and Salivary Flow
Source: Deng G, et al. Functional magnetic resonance imaging (fMRI) changes and saliva production associated with acupuncture at LI-2 acupuncture point: A randomized controlled study. BMC Complement Altern Med 2008;8:37.
Goal: To explore via fMRI the neuronal pathways potentially involved in acupuncture's effects on salivary flow.
Study design: Randomized, controlled (each person serving as her/his own control), subject-blinded, crossover descriptive trial.
Subjects: Healthy volunteers (n = 20; 10 females; median age, 30 years).
Methods: Subjects were randomized to receive both true and sham acupuncture in random order, one following the other after approximately one minute's delay. True acupuncture was performed on the non-dominant hand at the LI-2 point (radial side of the index finger just palmar to the metacarpophalangeal joint). Needles were twisted gently after insertion. Sham acupuncture was performed on the same arm using a Streitberger needle (no actual skin penetration, but a sensation that there has been) at a non-acupoint location of the ulnar forearm. Salivary production was determined via weighing of a cotton gauze pad placed in the mouth beside the buccal opening of the parotid gland. Cortical activity was evaluated using fMRI. After subjects came out of the fMRI they were advised that one of the acupuncture treatments was real and the other sham, and were then asked to identify which was which.
Results: Unilateral LI-2 needle stimulation was associated with bilateral activation of the insula and adjacent opercula (parietal, rolandic, and frontal) without signs of deactivation. Sham acupuncture at the nearby site induced neither cortical activation nor deactivation. In addition, true acupuncture induced slightly greater salivary production than sham acupuncture.
Conclusion: Unilateral acupuncture at LI-2 is associated with a mild increase in salivary flow and specific, yet bilateral, cortical activation.
Study strengths: Successful degree of blinding; use of well-studied acupoint.
Study weaknesses: Small sample size; data only available for 12 subjects due to head movement during fMRI and because one person was left-handed; unusual sham acupuncture (to avoid measuring dose response or point specificity, but still...).
Of note: The acupuncture point LI-2 is commonly used in clinical practice to treat dry mouth (xerostomia); previous data have suggested that acupuncture can increase salivary flow in healthy subjects, those with Sjogren's syndrome, and in people with a history of radiation therapy to the head and neck region; subjects in this study had to keep the cotton gauze in their mouths for 8 minutes and 40 seconds without swallowing; the fMRI patterns seen here overlapped somewhat with areas typically involved with pain perception; expectation is known to induce salivary flow; the insular and opercular activation noted during this trial are typically associated with visual, olfactory, and gustatory stimuli; hypersalivation is seen with temporal lobe seizures.
We knew that: The majority of clinical acupuncture research has focused on pain suppression, but acupuncture can be used to stimulate activity, too; studies of acupuncture and pain suppression that employed fMRI reveal modulation of brain activities in areas involved with signal processing; the mechanism of action of acupuncture in stimulating salivary production remains unknown.
Comments: Acupuncture studies that employ fMRI are so intriguing. At a simple level, the fact that unilateral needle placement is associated with bilateral cortical activity is, well, cool. Readers of Alternative Medicine Alert should go to the library and look at the fMRI pictures in the articlethey are fascinating. The authors are quick to point out, however, that theirs is a descriptive study, thus cause and effect cannot be ascertained from the data so far presented, but the data do create new hypotheses that can, and will, be tested. Such studies are clearly important for those who experience the discomfort of xerostomia, but they are also important for the furthering of foundational research into the precepts of Asian medicine.
There is little to garner from this paper that can be put into play in clinical practice. The point of including it in this month's Alternative Medicine Alert is to remind us all of the wonder of the human body, the potential yet to be fully realized in so many therapies, and the importance of applying miraculous technologies to investigate even the oldest of medical interventions, and so help distinguish the useful from the useless.
What to do with this article: Keep a copy of the abstract on your computer.
Cals and Carbs: Diet and Weight Loss
Source: Shai I,et al. Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet. N Engl J Med 2008;359:229-241.
Goal: To compare the effectiveness and safety of three different nutritional protocols, focusing on weight loss and metabolic parameters.
Study design: Two-year dietary trial in an Israeli workplace (research center) with an on-site medical clinic.
Subjects: Middle-aged people determined to be moderately obese (mean age, 52 years; mean BMI, 31 kg/m2; 86% male); only 272 (n = 322) completed the entire trial.
Methods: Subjects were randomly assigned to one of three diets: a low-fat calorie-restricted diet, a Mediterranean calorie-restricted diet, and a low-carbohydrate non-calorie-restricted diet. The low-fat calorie-restricted diet was based on American Heart Association guidelines and allowed for an energy intake of 1,500 kcal/1,800 kcal for women and men, respectively. The Mediterranean calorie-restricted diet contained a moderate amount of fat, was rich in vegetables and low in red meat, and permitted the same total calorie intake as the low-fat group. The low-carbohydrate, non-calorie-restricted diet aimed to provide 20 g of carbohydrates per day during the two-month initiation phase, with a gradual increase to 120 g/day to maintain weight loss (intervention largely based on the Atkins diet). Each dietary group was assigned a registered dietitian who met with their groups for 90 minutes during weeks 1, 3, 5, 7 and thereafter at six-week intervals (total of 18 sessions). A group of spouses received training to help support participants. Food frequency questionnaires were completed and a subgroup of subjects completed two repeat 24-hour dietary recalls. Physical activity level was also determined via questionnaire. Weight, BMI, and waist circumference were determined monthly, while blood pressure was measured every three months. Fasting blood samples for chemistries were obtained at baseline, six, 12, and 24 months. Motivational telephone calls of 10-15 minutes duration were made by another dietitian to those subjects having difficulty adhering to their diet at six times during the two-year program. The primary endpoint of interest was weight loss at 24 months.
Results: Daily energy intakes decreased significantly and physical activity increased among all three intervention groups. Subjects in all three groups lost weight, but weight loss was most significant in the low-carbohydrate and Mediterranean diet groups. Among those who completed the entire study, mean weight loss was 3.3 kg for the low-fat diet subjects, 4.6 kg for the Mediterranean diet group, and 5.5 kg for the low-carbohydrate diet subjects. At trial's end, urinary ketones were more likely to be found in subjects in the low-carbohydrate group. Among the 36 subjects with diabetes, more favorable changes in fasting blood sugar and insulin levels were seen in the Mediterranean diet group than in the low-fat diet subjects. The relative reduction in total cholesterol:HDL-C was 20% in the low-carbohydrate diet group and 12% in the low-fat diet group; triglyceride levels likewise dropped in the low-carbohydrate group more than in the low-fat diet group. C-reactive protein levels dropped significantly only in the Mediterranean diet group, while adinopectin levels increased and leptin levels decreased in all groups. All three groups showed significant decreases in blood pressure and waist circumference, but there was no difference between groups.
Conclusion: Low-carbohydrate and Mediterranean diets may be effective alternatives to low-fat diets for weight loss. Dietary interventions for weight loss should be tailored to a person's unique tastes and metabolic considerations.
Study strengths: Compliance rates (95% at 1 year, 85% at 2 years); subjects stratified by age, BMI, presence of chronic disease, and gender; intention-to-treat analysis; study duration; measurement of biomarkers.
Study weaknesses: Predominantly male subjects; physical activity level measured only through questionnaire; workplace model not readily generalizable (though interesting from a corporate health perspective).
Of note: Long-term studies of low-carbohydrate diets have been lacking; participants got lunch (the main meal in Israel) at their workplace cafeteria where the dietitians worked closely with kitchen staff to prepare and label foods according to the specifics of each dietary study group; the low-carbohydrate group consumed the most protein, fat, and cholesterol; subjects in the Mediterranean diet group consumed the most fiber, and had the highest ratio of monounsaturated:saturated fat intake; adherence to a Mediterranean-style diet has been associated with significant cardiovascular health benefits; compliance at 2 years was worst in the low-carbohydrate group (78%); in this study, maximal weight loss occurred within the first six months.
We knew that: Even a moderate degree of weight loss in overweight individuals confers known health benefits; trials of different weight loss diets typically suffer from short follow-up times, unequal intensity of intervention, and high dropout rates; low-carbohydrate diets are typically high in both fat and protein, while Mediterranean-style diets contain a moderate amount of fat, with a high proportion of monounsaturated fats; high intake of monounsaturated fats is associated with improved insulin sensitivity.
Comments: As the "diet wars" continue without end in the mainstream media, a welcome degree of clarity is manifesting in the medical literature, to which the present article contributes significantly. Yes, all three diets appear effective and safe, but perhaps the most welcome aspect is the notion that weight loss diets need to be individualized, and take into account not only personal taste preferences, but also the unique metabolic make-up of every individual. If an overweight individual also has diabetes, perhaps a calorie-restricted, Mediterranean-style diet would be most appropriate. For those who simply aren't able to watch their calorie intake, a low-carbohydrate, non-calorie-restricted diet might be the ticket. For those whose tastes run counter to an Atkins-style diet, a low-fat option seems both safe and at least somewhat effective, too. So the dietary approach to weight loss then not only accounts for biochemical concerns, but the person's enjoyment of food, too. Yes, "let food be thy medicine," but let it be more than just medicine by paying attention also to our patients' unique dietary likes and dislikes. An article such as this is nothing less than a breath of fresh air.
What to do with this article: Make copies to hand out to your peers.
Goal: To explore via fMRI the neuronal pathways potentially involved in acupuncture's effects on salivary flow.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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