Salt And Heart Disease

Is salt in the diet bad for the heart? This question is often asked because it has been suggested that a high salt intake may promote high blood pressure and because many heart patients are advised by their doctors to eat a low salt diet.

Salt restriction is important for the patient with heart failure because it helps to control oedema. In heart failure the heart is sluggish in moving the blood along from the veins to the arteries with the result that a back pressure builds up and fluid tends to accumulate in the body. This waterlogging (oedema) is both distressing and a serious complication. The extra weight of the oedema fluid, which may range from 20 to 60 pounds or more, means that every movement of the body demands excessive work from an already overburdened heart. Fluid in the lungs interferes with respiration and the patient may literally drown from oedema of the lungs.

Oedema fluid is a dilute solution, like the other fluids of the body, and cannot be formed unless both salt and water are available. Preventing oedema by water restriction is difficult and extremely disagreeable for the patient. But salt restriction, though not very pleasant, can be effective; without salt, the kidneys, if they are in reasonably good shape, get rid of excess water because the kidneys strive to maintain a constant salt concentration in the blood.

In the normal person there is no back pressure in the blood to push fluid into the tissues, and the kidneys readily control the salt concentration of the blood over a wide range of both salt and water intake. The situation is very different from that in the heart patient who is in or near heart failure. There is no reason to argue that because salt restriction is good in heart failure it, therefore, may help prevent heart disease.

Salt restriction is also sometimes employed in the treatment of hypertension, even though there is no sign of heart failure. The rice-fruit diet is one form of this salt restriction treatment. This is a rather heroic measure because anything short of true salt starvation is ineffective; the salt restriction must be extreme. Special foods and methods of cooking are required, and even with the greatest efforts this treatment is often unsuccessful in controlling severe hypertension. Obviously this is a special treatment for special patients; the fact that it sometimes works does not justify the claim that a high salt diet causes hypertension or that a low salt intake will help prevent the disease.

Arguments against a high salt intake for persons who have neither heart failure nor hypertension are based mostly on the observation that enormous salt doses given to rats may damage the kidneys and result in hypertension. But human diets never approach the salt loading used in such experiments, and it is questionable whether these animal experiments are relevant to human diets. As in other problems of heart disease, reasoning from artificial extremes in animal experiments may be misleading.

Still, it is interesting to note that persons who habitually salt everything are reported to have, on the average, somewhat higher blood pressures than do those who taste first and then decide whether or not to add salt. No difference between these types of people in the incidence of actual hypertension has been proved, however. In Japan, where the amount of salt in the diet is high, the incidence of hypertensive disease is also high. Many doctors in Japan blame the salt in the Japanese diet, but there is no real evidence that it is actually the reason for so much hypertension in Japan.

The conclusion from all this, we think, is that real salt restriction should not be attempted except on the advice and under the supervision of a doctor but that moderation in salt use is sensible for everyone. Incidentally, "salt" here means not only common salt, that is, sodium chloride, but also flavourings such as sodium glutamate which derive their salty taste from the sodium in them.

Some people naturally crave more salt than the average, but excessive salt use is often the result of attempting to put taste into otherwise tasteless food. After a while dousing everything with salt may become a habit, just like putting butter on everything. In both cases the answer to prevent and correct bad eating habits is in better cookery.

Drugs And Special Anti-Cholesterol Agents

Doctors now have available many potent drugs for the management of heart disease, drugs to strengthen the action of the heart muscle (e.g., digitalis and related compounds), to help keep the heart beat regular (e.g., quinidine), to relieve the acute pain of angina pectoris (e.g., nitroglycerine), to lessen the tendency of the blood to clot (e.g., heparin and dicumarol), to help the body get rid of the excess water that collects in heart failure (the diuretics), antibiotics to reduce the danger of rheumatic fever, and a wide variety of drugs to reduce the blood pressure. All of these can be valuable and even life-saving when properly prescribed for suitable patients; none should be used except on the advice and under the control of a doctor.

Lately, doctors, their patients and many clinically healthy people are hopefully asking about drugs for the control of the lipids, especially cholesterol, in the blood. And pharmaceutical manufacturers are anxious to oblige. For a time various vitamin preparations and so-called "lipotropic agents" were promoted and many are still on the market, particularly in the United States. Lecithin, choline, inosital, pyridoxine (vitamin B6) were particularly touted. But all of these are increasingly hard to sell in the face of uniformly negative reports from properly controlled investigations. Now two new approaches are offered.

The first is suggested by a central point made in this book, namely that while saturated fats raise the serum cholesterol level, some liquid oils, those rich in poly-unsaturated fatty acids, tend to depress it. So why not seek out such oils, dress them up a bit and sell them through the high-profit drug trade for the control of the blood cholesterol? Soon after the word about the diet fat-cholesterol story began to get around, half a dozen pharmaceutical firms were in the business, adding some vitamins or "lipotropes" or colour or flavour, making emulsions and offering fancy packages to the public at a price many times what the essential ingredient, the oil, would bring otherwise.

The favourite of the oils used in this way is safflower oil because it is very low in saturated fats (5 to 10 per cent) and very high in poly-unsaturated fats (up to 80 per cent). The seed oils of the poppy, passion fruit and sunflower have much the same composition and action but have not been so popular with the drug houses. These preparations are not dangerous and, when used in fairly generous amounts, at least an ounce (30 cubic centimetres) daily, will generally have some effect in lowering the blood cholesterol. But safflower and these other oils are full of calories (9 Cal. per gram or over 200 Cal. in a fluid ounce). Besides, we object to selling a simple food item as a drug at a great differential in cost to the consumer. In any case, these poly-unsaturated fat materials, whether taken as a drug or as a food, offer no cure but, at best, a method of help to manage the blood cholesterol level; you must keep on taking them indefinitely to maintain any benefit. We think it better to incorporate such materials in the regular diet.

The second new approach is the use of niacin (nicotinic acid) in very large amounts. The vitamin effect of niacin (the "anti-pellagra vitamin") is achieved with a few milligrams a day, provided by any good diet. But if thousands of milligrams of niacin are ingested daily the serum cholesterol generally declines and stays reduced so long as the dosage is maintained (usually 3 to 10 grams every day).

How this effect is produced is unknown. Curiously, niacin amide, which is equally potent as a vitamin, has no effect on the cholesterol level. This is a pity, for niacin, in any single dose of the order of 50 milligrams or more, causes a violent flushing and itching of the skin whereas niacin amide does not. The flush and itch usually last less than an hour after taking niacin and it is reported that in most patients this highly unpleasant reaction ceases or is reduced after a few weeks of dosage.

Summing up, here is our best advice: Do not get fat; if you are fat, reduce.

Restrict saturated fats, the fats in beef, pork, lamb, sausages, margarine, cooking fats and fats in dairy products.

Prefer vegetable oils to solid fats, but keep total fats under 30 per cent of your diet calories.

Favour fresh vegetables, fruits, and non-fat milk products.

Avoid heavy use of salt and sugar.

Good diets do not depend on drugs and fancy preparations.

Get plenty of exercise and outdoor recreation.

Be sensible about cigarettes, alcohol, excitement, business strain.