Q. I was interested in your description of how fish oils may protect against heart disease. But what about reports that suggest they may be helpful in treating rheumatoid arthritis?

A. This line of investigation certainly warrants further study, but we are far from suggesting a dietary treatment for the disease.

The rationale for human studies was based on observations of animals, which demonstrated that changes in dietary fat can affect arthritis. This effect may be related to their influence on the production of prostalandins, hormone-like substances that seem to have a wide range of uses in the body.

A report from Albany Medical College appeared several months ago in the British medical journal Lancet. It described a study demonstrating that dietary fats may affect rheumatoid arthritis in humans. But the results were neither clear-cut nor dramatic.

In that study, 37 patients were enrolled in a 12-week double-blind feeding trial. The experimental group ate a diet low in fat and high in vegetable oil. They were given 10 capsules a day of fish oil derivative containing generous amounts of one of the omega-3 fatty acids. The control group ate a typical American diet high in saturated fat and low in polyunsaturates. But in order to disguise it, "random" changes were made. They were given placebo capsules. After 12 weeks, patients were asked to return to regular diets.

There were no differences in a number of biochemical and clinical measures between the two groups. And because the course of the disease is so variable, any effect could have occurred by chance.

On the other hand, during the first two weeks after the study was terminated, the experimental group had significantly more pain and poorer general health than while on the diet, while the condition of those in the control group did not deteriorate. This observation suggests, but hardly proves, that the diet was of some benefit.

The conclusion is best summed up by the authors: "Our results show a clear, though modest difference, between the experimental and control groups in some of the clinical manifestations of rheumatoid arthritis." But before any definite conclusions can be made, the study would have to be repeated over a longer period and with more patients.

In addition, questions have been raised about the wisdom of using a diet rich in vegetable oils for the experimental group. There is some reason to believe that the effect might have been greater if a traditional American diet had been used. Indeed, the authors of the study suggest that one important next step will be to compare the effects of vegetable oil and fish oil separately.

Q. Is it possible to make a really clear ice ring with flowers or fruit in it? I've tried many times, each version being partly cloudy. I understand the cloudines has to do with dissolved gases and that boiling removes them. Nevertheless, the rings made with boiled water are just as cloudy. Any other bright ideas?

A. The cloudiness does, indeed, have to do with dissolved air, mainly oxygen. Professional ice carvers, who order their ice in very large blocks, face the same problem at times.

Commercial ice makers prevent cloudiness by bubbling air through the water in a can set in a sub-freezing brine. A copper tube inserted in the middle of the can bubbles compressed air through the freezing water. When the ice freezes to within two inches of the copper tube, it is withdrawn. Because the ice cake is so large (300 pounds) and because the brine is kept between 6 and 10 degrees, 24 hours are needed to produce a solid block.

Judging from millions of aquariums and billions of pet fish, one would expect aeration actually to be adding more oxygen. However, this is not true, as the freezing water is already saturated. Instead, the air bubbles agitate the water, pushing waves of water molecules past the cold, outer surfaces of the block's mold. This agitation deposits layers of ice on the container's walls. And, because the rate of freezing is slow, the ice formed contains no trapped gases.

This kind of freezing cannot be done in the home environment, as you would have to find an efficient way of agitating the water while holding it in the freezer. 1985, Washington Post Writers Group because the rate of freezing is slow, the ice formed contains no trapped gases.

This kind of freezing cannot be done in the home environment, as you would have to find an efficient way of agitating the water while holding it in the freezer. 1985, Washington Post Writers Group