We read with interest the recent analysis of Stamler et al but question their conclusion that “glutamic acid may have independent blood pressure lowering effects which may contribute to the inverse relation of vegetable protein to blood pressure.” The main dietary sources of glutamic acid are meats, poultry, fish, eggs, and dairy products. As reported by Stamler et al, meat and cheese account for 47% of consumed glutamic acid in the United States. One simple beef burger of 140 g contains 5.6 g of glutamic acid, and cheeses such as Roquefort and Parmigiano are particularly rich in glutamic acid, containing as much as 1,200 mg/100 g of cheese. There is some nutritional evidence that burgers and cheese, despite being high in glutamic acid, add to the epidemic of obesity and the metabolic syndrome. As to antihypertensive effects, a thorough double-blind study evaluating the effects of oral intake of 3 g monosodium glutamate in 73 healthy subjects did not document any change in blood pressure (BP) compared with placebo.
In a prospective thorough randomized study, the Dietary Approaches to Stop Hypertension (DASH) diet (in which the main sources of glutamic acid remain beef and pork) has been shown to reduce BP, whereas no health benefit has been reported with the so-called Super-Size Me diet. By using the same technique as the study of Stamler et al, we estimated glutamic acid content in the DASH diet and compared it to such a Super-Size Me diet ( Table 1 ). One might argue that the caloric excess and the high sodium content of such a diet could counteract the BP-lowering effects of glutamic acid. However, even when corrected for the same number of calories, glutamic acid content remains slightly higher in the Super-Size Me diet than in the DASH diet.
| Diet | Calories | Glutamine (g) | Protein (g) | Sodium (mg) | Potassium (mg) | Magnesium (mg) | Calcium (mg) |
|---|---|---|---|---|---|---|---|
| Super Size Me | 5,000 | 42.5 | 222.7 | 8,104 | 4,005 | 360 | 1,970 |
| Super Size Me | 2,100 | 17.9 | 95.3 | 3,402 | 1682 | 151 | 827 |
| DASH | 2,100 | 15.4 | 87.5 | 2,859 | 4,414 | 481 | 1,264 |
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