Carbs vs. protein vs. mono fats.

Experts agree that it's a good idea to minimize bad fats (saturated and trans). But it's not clear whether to replace them with carbohydrates, protein, or monounsaturated fats.

The OmniHeart Trial gave men and women with high blood pressure or pre-hypertension one of three diets that had roughly equal amounts of saturated fat, sodium, potassium, calcium, fiber, and calories. However:

* the higher-protein diet had slightly more beans, low-fat dairy foods, poultry, and egg substitutes,

* the higher-carb diet had more sweets and desserts and slightly more fruit and juices, and

* the higher-mono diet had more fats and oils and slightly more vegetables.

Compared to the higher-carb diet, the higher-protein diet lowered blood pressure, LDL ("bad") cholesterol, and triglycerides (that's all good), but it also lowered HDL ("good") cholesterol (that's bad).

Compared to the higher-carb diet, the higher-mono diet lowered blood pressure and triglycerides and raised HDL cholesterol (that's all good) and had no effect on LDL.

What to do: Either higher-protein or higher-mono diets beat higher-carb diets, say the authors. But their results might not apply to a higher-carb diet rich in whole grains rather than sweets and desserts.

In any case, it makes sense to replace bad fats (in fatty meats, high-fat dairy, butter, etc.) with beans, vegetables, low-fat dairy foods, oils, and nuts instead of desserts, sweets, and fruit juices. But don't go overboard: none of these diets were extremely high or low in protein, fat, or carbs.

Journal of the American Medical Association 294: 2455, 2497, 2005.