Clinical Briefs

By Louis Kuritzky, MD

Effect of the Dietary Approaches to Stop Hypertension Diet and Reduced Sodium Intake on Blood Pressure Control

The Dietary Approaches to Stop Hypertension (DASH) diet, which suggests high intake of fruits, vegetables, and low-fat diary products, has been shown to favorably affect blood pressure in Stage 1 Hypertension (140-159/90-99) as well as pre-hypertension (130-39/85-89). A reduced sodium intake diet (RSI) has also been shown to have beneficial BP effects in these groups. Whether the combination would provide additive benefits was the subject of this trial. Subjects (n = 412) were randomly allocated to DASH or control diets with high (142 mmoL/d), intermediate (107 mmoL/d), or low (65 mmoL/d) sodium content. Study subjects ate the DASH (or control) diet for 3 consecutive 30 day intervals, each interval with a different sodium content. To ensure compliance and consistency, all meals were provided by Svetky and colleagues.

Adding sodium restriction to the DASH diet resulted in a 2-2.6 fold greater likelihood of BP being controlled. At the lowest sodium intake, 84% of hypertensive patients achieved BP control (< 140/90). In persons with isolated systolic hypertension, the pattern of responsivity was similar. In persons with high-normal BP, 76% were restored to normotension with DASH+RSI.

Application of these dietary modulations has meaningful beneficial effects, and may obviate or reduce the need for pharmacotherapy.

Svetkey LP, et al. J Clin Hypertens. 2004;6:373-381.

Methylprednisolone, Valacyclovir, or the Combination for Vestibular Neuritis

Vestibular neuritis (VN) is characterized by acute onset of vertigo, a positive Romberg’s sign, nystagmus, and nausea. It is second only to benign paroxysmal positional vertigo as a cause of peripheral vestibular vertigo. The most popularly favored putative cause of VN is herpes simplex virus, although other etiologic explanations (like vestibular ischemia) are also suggested. Full vestibular recovery from VN occurs in less than half of cases, leaving patients with deficits such as postural imbalance during walking.

Corticosteroids, antiviral agents, or both are sometimes used to treat VN, but little evidence exists to confirm or disprove the efficacy of such interventions. This study compared methylprednisolone (MPD), valacyclovir (VAL), the combination (MPD + VAL) and placebo in subjects (n = 141) with acute VN of less than 3 days duration. MPD was administered orally QAM for 22 days, titrated 100 mg daily down to 10 mg. VAL was dosed 500 mg t.i.d. orally for 7 days.

At 12-month followup, the improvements in vestibular paresis ranged from 36.0% (VAL) to 39.6% (placebo), 59.2% (MPD + VAL), and 62.4% (MPD). These data do support the beneficial effects of corticosteroids, but do not support efficacy of VAL in VN.

Although it is possible, and data in herpes encephalitis supports this concept, that VAL was not administered early enough in the disease process to have a favorable impact, since patients were seen within the first 72 hours of disease, it is unlikely that clinicians will be provided any opportunity for earlier drug administration.

Strupp M, et al. N Engl J Med. 2004; 351:354-361.

Improved Plasma Glucose Control, Whole-Body Glucose Utilizations, and Lipid Profile on a Low-Glycemic Index Diet in Type 2 Diabetic Men

At the same level of grams of carbohydrate, different foods vary in their rate of rise of plasma glucose, and in the subsequent amount and timing of insulin response they elicit. In theory, consumption of foods with a favorable (ie, low) glycemic index should favorably affect diabetic control. To date, there have been insufficient data to confirm or refute the role of a dietary choices based upon glycemic index. Supporting the role of a low glycemic index diet (LGI) are data that indicate better A1c levels and reduced fat mass, even in the absence of a measurable effect upon plasma glucose.

Rizkalla et al studied diabetic men (n = 12) who were administered a LGI diet vs a high glycemic index diet for 4 weeks, followed by a 4 week washout and then crossover to the other diet.

Numerous statistically significant favorable changes occurred during the LGI phase, including impact on fasting glucose, A1c, glucose use, LDL, plasma fatty acids, and even fibrinolysis status, as indicated by plasminogen activator inhibitor activity. If these effects are sustainable, they could have important positive long-term effects on diabetes.

Rizkalla SW, et al. Diabetes Care. 2004;27:1866-1872.

Dr. Kuritzky, Clinical Assistant Professor, University of Florida, Gainesville, is Associate Editor of Internal Medicine Alert.