Q. It's often said that elderly people living alone consume poorer diets than those who live with someone. Is that really true, or is it just a myth?

A. For some groups of the elderly, it does appear to be true, though the explanation might surprise you. Rather than consuming a poorer diet because they subsist on nothing but tea or toast, the problem is that they simply eat less food. The foods chosen are nutritionally comparable, but not eaten in sufficient quantity.

This information comes from Maradee A. Davis PhD and her colleagues at the University of California at Berkeley. Using three-day intakes obtained from the 1977-78 National Food Consumption Survey, they classified diets of those 55 and older into two groups: either poorer or higher quality. The rather broad classification was based on whether an individual had consumed less than two-thirds of the RDA for five of nine nutrients, including vitamins A, C, B-6, B-12, thiamine, riboflavin, iron, calcium and magnesium.

Overall, 13 percent of the participants' diets were classified as poor. Most striking was the finding that 25 percent of men 75 and older living alone consumed diets ranked as poor. Close behind, 22 percent of the women in the age range 55 to 64 who lived alone also subsisted on inferior diets. And in general, poor diets were more likely to be found among women than among men living alone.

As stated, what made the difference was not the nutritional quality of the foods consumed, but the number of calories taken in. That is, poor diets were more likely to be found among those who ate less.

Although the data used are now over 10 years old, there is little reason to think the picture has changed. With the rapid growth of the elderly in our population, we have an added incentive to study the complex factors affecting diet quality and to develop programs to help older people maintain sound nutrition. Meanwhile, if you are an older person who lives alone (or the friend or relative of one who does), do what you can to ensure that your (or their) diet contains sufficient nutrients, including calories.

Q. Are cod and scrod the same? How do they compare nutritionally?

A. Scrod is the term used to describe small young cod, that is, fish weighing up to 2 1/2 pounds. However, it may also be used to describe several other young fish, particularly haddock. And young pollock, which is slightly more dense and also contains somewhat more fat, is also sold as scrod.

The age and size of fish doesn't affect their nutrient profiles. Whether you buy cod or young cod sold as scrod, a whole pound of fish will contain about 355 calories, nearly all from protein. The same pound of young pollock sold as scrod would have about 75 calories more, because it contains a still very modest 4 grams (less than a teaspoon) of fat. Since a pound of fish would easily serve three people, the per-person difference is insignificant.

The real trick, though, is to make sure preparation methods don't turn low-calorie fish into a high-calorie meal. One simple way to prepare any of these fish is to place them on a bed of lightly saute'ed onions. Then, dust with fresh pepper and a hint of salt and coat with fat-free yogurt that has been seasoned lightly with curry powder.

Add a small amount of white wine to the baking dish and bake at 350 degrees until the fish flakes easily with a fork, about 30 minutes. The whole seasoning process adds fewer than 50 calories per serving.

Q. What are the origins of the restaurant?

A. The word dates back to the 16th century. But then it meant not a place to sit down and be served but a food that "restores." Specifically, it referred to a rich, highly seasoned soup that could restore strength. Gradually it evolved to mean an establishment selling foods with restorative powers.

Records indicate that the first restaurant was opened by a Frenchman named Boulanger, who sold bouillon described by him as "a restorative fit for the gods." Two others followed the next year, billed as "houses of health." And in 1782, more than 200 years ago, what we'd describe as a restaurant in the modern sense opened in Paris. It was in the Grand Taverne de Londres that the novel concept of listing dishes on a menu and serving diners at fixed hours at small individual tables was introduced.

But the French Revolution gave real impetus to the development of restaurants. Guilds were abolished. The cooks and servants whose employers had fled their Paris estates created the necessary labor pool. And the arrival of people from other parts of France provided another essential ingredient, customers.

Q. Are fresh vegetables nutritionally superior to canned ones? I've heard conflicting reports.

A. Perhaps the reason you've heard different answers is because the comparison depends on the quality of the produce at the time of harvest and on how it's handled from then until eaten. Produce picked at the peak of ripeness, handled carefully and eaten within a short time is likely to be in its nutritional prime. But if it's held for several days under suboptimal conditions of light and temperature before being sold, prepared and consumed, nutritional quality will deteriorate.

In this country, food processors harvest produce at the pinnacle of maturity and begin the canning process as quickly as possible to stop the action of enzymes and control other factors that lead to a decline in quality. And processing techniques are designed to minimize losses.

For the consumer, the most important thing is to be sure to eat plenty of fruits and vegetables. To the extent that they are of high quality at a price you can afford, it's a good idea to emphasize fresh vegetables and fruit. By the same token, there are many times when canned produce is definitely the preferred option. They should not be viewed as a nutritional compromise. Indeed, when compared to a similar serving of mishandled fresh produce, it is quite possible that their nutrient levels will be higher.