The Dietary Approaches to Stop Hypertension (DASH) studies sponsored by the National Heart, Lung and Blood Institute at NIH in the 1990s were large, carefully controlled feeding studies for lowering blood pressure.
The DASH studies took a holistic approach to provide a combination of previously tested dietary recommendations (higher potassium, higher calcium, higher fiber, lower saturated fat and salt, moderate protein and calories) through a total diet of real food rather than with pills or supplements.
The DASH Diet is:
- higher in vegetables and fruits (potassium, fiber, vitamins, low salt)
- higher in whole grains (fiber, some potassium and vitamins)
- higher in low-fat dairy products (calcium, protein, low-saturated fat)
- and lower in meats and saturated fats (lower in salt and sat. fat)
than the average American diet. In short, it combines the elements that heart disease and cancer experts have been advocating for years.
It’s also designed to be moderate in calories, with example days for diets in the range of about 1600-2600 calories, normal-weight recommendations for men and women, plus one at a higher range of 3100 calories. Although it wasn’t designed specifically for weight loss, the DASH guidelines include tips for for people who usually eat more than a normal-weight diet to move toward a balanced lower-calorie diet using the charts. The DASH Diet guidelines with examples and recipes and tips etc. are available free from NHLBI.
Why lower sodium?
Dietary sodium is the nutritional factor most strongly and directly connected with high blood pressure, which can lead to heart attacks and stroke. Habitual high sodium intake forces the body to retain more water to keep the bloodstream from getting too concentrated in sodium–the extra water volume puts more pressure and strain on blood vessels and the heart, which can end up enlarged and unable to work efficiently. High blood pressure can cause macular degeneration, damage to the small blood vessels in the eye that can lead to blindness. Although there are numerous blood pressure medications and they work well, they all have undesirable side effects, they cost a fair amount of money, and they need to be taken daily to work. Preventing high blood pressure through a balanced diet like the DASH Diet, combined with exercise and weight control, is a better plan if you’re not already to the point of needing medication, and if you do take medication, a DASH-style diet will help make it more effective.
Lowering dietary sodium by moderate amounts can bring higher blood pressure down slightly but it also prevents it from rising further. Lowering sodium aggressively through diet has shown dramatic results in patients hospitalized with extremely high “malignant” blood pressure–in a series of well-documented cases it reversed high blood pressure, edema (swelling) and heart size and in some patients even restored lost vision.
- New CDC and NHLBI recommendations for people who are over 40, overweight (about 2/3 of American adults), or have elevated blood pressure call for 1500 mg. sodium per day. The DASH guidelines show you tricks for cutting back, and it’s a lot easier than you might think.
- For most people, following the standard “normal salt” DASH Diet is a natural way to cut down on salt without really trying.
- Eating more “whole foods” and less packaged, processed or restaurant food, and not adding salt to what you cook is a good way to cut back on salt without feeling deprived.
- Drinking water instead of soda is another fast way to cut salt.
- Unless they’re canned, fruits and vegetables shouldn’t contain anything but trace amounts of sodium.
- Cow’s milk naturally contains a moderate amount of sodium, about 125 mg/8 oz., and dairy products should probably be chosen not just for low fat but lower sodium as well if you’re looking to cut back on salt. Natural yogurt contains slightly more sodium than plain milk, 150-180 mg/8 oz cup.
- Most cheeses list salt as an added ingredient and contain about 200 mg/1-oz serving. Two to watch out for, though: buttermilk has 250 mg/8 oz, and cottage cheese is much higher in salt than you’d expect– these days commercial cottage cheese runs 490-500 mg sodium/8 oz serving.
- Potassium is important because it appears to maintain lower blood pressure by counteracting dietary sodium or displacing it, and Americans today tend to get too little.
- However, because it’s directly cardioactive as well, potassium supplements or pills can be dangerous for people not specifically taking it under a cardiologist’s supervision (accidental overdoses can lead to sudden cardiac arrest, etc.) It’s much safer for most people to get their potassium from whole foods instead.
- Fruits, vegetables, and some dairy foods are good sources of potassium. All of these should be unsalted for the best results.
- Calcium has been shown to have a smaller but still important role in supporting healthy blood pressure levels, as well as a large role in muscle function and bone density.
- Calcium supplements are generally safe but it’s still best to get your calcium from dietary sources if you can–not least because eating calcium-rich foods in preference to standard junk or processed foods means you get more nutrition per calorie, it tastes better, and you’re not spending extra money.
- If you don’t eat dairy, or you’re vegan, you can get your calcium through a variety of vegetable sources–tofu is only one.