What kind of diet would lower high blood pressure? A diet low in sugar and salt and high in potassium.
Potassium has the opposite effect of sugar upon the biochemistry of the body. Sugar increases secretion of insulin. Potassium lowers secretion of insulin. Sugar causes retention of sodium by the kidneys, thus raising blood pressure. Potassium causes excretion of sodium by the kidneys, thus lowering blood pressure. Sugar constricts the smooth muscle cells surrounding the arteries, thus increasing resistance to blood flow and raising blood pressure. Potassium relaxes the smooth muscle cells of the arteries, thus decreasing resistance to blood flow and lowering blood pressure. Sugar raises triglyceride and cholesterol levels and increases cholesterol deposits in the arteries. Potassium lowers cholesterol levels and decreases cholesterol deposits in the arteries.
Evidence in support of a high potassium diet
Given these effects of potassium, we would expect people with hypertension to have low levels of body potassium. Numerous studies have confirmed that this is indeed the case. The question then arises: Could increasing potassium levels by eating a diet rich in potassium lower blood pressure in people with hypertension? Two studies were done to answer this question. The first was an Australian study done in 1982, and the second was a study done in Italy in 1991. They had almost identical results: increasing dietary potassium in hypertensive subjects by increasing consumption of natural, unprocessed foods (legumes, fruits and vegetables) high in potassium allowed a more than 50 percent reduction in anti-hypertensive drug dosage in four out of five patients. One out of three developed normal blood pressure even when all drugs were discontinued. The investigators concluded: "Increasing dietary potassium intake from foods is a feasible and effective measure to reduce anti-hypertensive drug treatment." Please note: Stopping some kinds of hypertensive medicines suddenly can be lethal. Adjustment of medication should be done only under a doctor's supervision.
High potassium foods
What foods are high in potassium and low in sodium? Fresh fruits, fresh vegetables, whole grains, legumes, fresh chicken, fish, meat - in fact, almost any food that has not had its naturally high potassium to sodium ratio diminished by commercial processing. Virtually all fresh fruits are excellent sources of potassium -not only the famous banana, but apples, oranges, lemons, grapefruits, grapes, pears, peaches, apricots, pineapples, mangoes, plums, melons, etc.
Fresh vegetables vie with fresh fruits as sources of potassium. They include potatoes, peas, beans, corn, lettuces, spinach, peppers, mushrooms, garlic, onions, broccoli, cauliflower, asparagus, Brussels sprouts, zucchini and any other vegetable you can think of. All legumes have a high potassium to sodium ratio. These include pinto, red, black, navy, garbanzo (chickpea), and kidney beans as well as lentils and split peas. Natural grains such as brown rice, wild rice, bulgur wheat, rolled oats and barley also have a high potassium to sodium ratio.
Foods to avoid
The foods to be avoided are commercially processed food. One of the processes used in canning is to put vegetables into a salt solution to separate the ripe ones, which float, from the unripe ones, which sink. Canned whole tomatoes and some canned or frozen fruits may be bathed in a solution of sodium hydroxide to remove their peel. The canning process usually involves boiling the food, which leaches out the potassium. The tasteless result is then flavored with sodium chloride.
Although most fresh meats have a reasonably high ratio of potassium to sodium, processed meats, including hot dogs, pork sausage, bacon, smoked ham, canned meats, and cold cuts such as bologna and salami, have very low potassium to sodium ratios. With respect to processed meats, in February 2002, a Harvard study appeared in the journal, Diabetes Care, that said the risk of diabetes is sharply boosted by a diet heavy in processed meats like hot dogs, bacon, and cold cuts.
Most of the vegetable oils sold in supermarkets have been extracted with harsh chemicals at high temperatures, bleached, and otherwise altered. (Extra-virgin olive oil, because it is so easily extracted is a healthy exception.)
Particularly avoid hydrogenated fats such as margarine and solid vegetable shortening. They contain trans fatty acids, which have been linked to risk of diabetes, obesity and immune dysfunction.
Shop around the perimeter of the supermarket, where you will find fresh food. Avoid the center of the store, where you will find the processed food - in cans, bottles, jar, boxes, packages and bags. A good rule of thumb - the closer the food is to the way it came out of the ground, the better it is for you.
Mary Lou Williams, M. Ed., is a lecturer and writer in the field of nutrition. She welcomes inquiries. She can be reached at 267-6480.