Take two walnuts ... and call me in the morning.

Okay. So maybe it is all in your head. But a bowl of chicken soup sure does wonders for your colds. And you seem to fall asleep easier after drinking a glass of warm milk. And didn't that recent bout of constipation clear up after a day or two on prune-juice detail?

Hmmm. Maybe there's something to this foods-as-drugs thing, after all.

This month we look at three possibilities.

Urinary tract infections account for more than six million visits to physicians or clinics each year. It's a particular nuisance for women, for older people, and for those with incapacitating conditions like multiple sclerosis.

Cranberry juice has been touted as a folk remedy for urinary tract infections for most of this century. Today, this "juice"--most brands are really about 25 percent juice and 75 percent sweetened water--is served in many nursing homes and hospitals to patients who are at risk of developing urinary infections.

Until about 1960, scientists thought that cranberry juice produced urine too acidic for the liking of bacteria that cause infections. Or that it flooded the kidneys and bladder with large quantities of a natural antibiotic called hippuric acid. Neither turns out to be the case.

Then, ten years ago, a new possible explanation surfaced. Before they can cause infections, bacteria must first adhere to the inside lining of the urinary tract. Something in cranberry juice seems to prevent them from doing that. Not all bacteria are vulnerable to the juice, though, and the limited protection lasts only as long as the juice is consumed regularly.(1)

The scientific literature isn't exactly overflowing with research on cranberry juice and urinary tract infections. In the only three studies that have been published, people either reported relief after drinking 1 1/2 to 3 glasses of juice every day for up to three weeks, or their urine cultures confirmed that many of the infections had improved(2,3,4)

Unfortunately, none of the studies was good enough to resolve the question.

For one thing, there were no controls (people with infections who drank a beverage other than cranberry juice). That flaw was avoided by a new, still-unpublished study from Harvard Medical School. Older women (average age: 78) who drank 10 ounces of cranberry juice each day for six months were 58 percent less likely to have a urinary tract infection than older women who drank a similar-tasting non-cranberry beverage.

Clearly, juicemakers are still far from having the "significant scientific agreement" that the Food and Drug Administration would require before allowing health claims about urinary tract infections on cranberry juice labels.

"That evidence just isn't there," concedes Mary Ann Rood, a spokesperson for Ocean Spray, the leading producer of cranberry products.

So, is it worth drinking cranberry juice?

"1 tell my patients that if they are prone to urinary tract infections they should drink lots of fluids, and that they should try cranberry juice to see if it works for them," says Washington, D.C., physician David Jacobs.

1 Journal of Urology 131: 1013, 1984.

2 Wisconsin Medical Journal 61: 282, 1962.

3 Southwestern Medicine 47:17, 1966.

4 Nursing Times 87: 36, 1991.

Nightshades: Arthritis or Wrong?

Can potatoes, tomatoes, eggplant, bell peppers, or other members of the "nightshade" family of vegetables cause arthritis?

The arthritis-nightshade connection dates from the early 1960s, when a professor of horticulture at Rutgers University named Norman Childers noticed that within an hour or two of eating nightshade vegetables, his joints and muscles became sore.

Childers began advertising in newspapers around the country, asking arthritis sufferers to eliminate nightshades from their diets. Within ten years, he had corresponded with thousands of people. Most reported at least some improvement.

A typical response: "I could not walk up the stairs without hanging on to the banister. Left shoulder and right toes ached all the time. All symptoms have disappeared since eliminating the nightshades. Bless you!"

Childers concluded that about ten percent of people suffering from arthritis are sensitive to something in nightshade vegetables.

Surveys like Childers', while interesting, aren't good evidence. We don't know how effectively the people eliminated nightshades from their diets. Or how much improvement was due to just having made an effort. Or how other treatments affected their symptoms.

In the 30 years since Childers came up with his arthritis-nightshade hypothesis, there have been no carefully controlled studies.

"There is no scientific evidence linking osteoarthritis to anything in the diet," says Arthur Grayzell of the Arthritis Foundation in Atlanta.

Half of all American 60-year-olds have some evidence of osteoarthritis ("osteo" means bone). It results when a breakdown of cartilage in a joint causes inflammation.

In rheumatoid arthritis, the inflammation is caused by an out-of-whack immune system. It affects from five to eight million Americans of all ages.

About five percent of rheumatoid arthritis cases may be caused by a food allergy, says Richard S. Panush, a professor of medicine at the University of Medicine and Dentistry of New Jersey. But those foods are seldom nightshade vegetables.

The only effective treatment for either form of arthritis is to relieve the pain with medication--usually aspirin or other non-steroidal anti-inflammatory drugs.

"Still," says Grayzell, "if someone experiences relief by avoiding certain foods, then I tell them to go ahead."

Walnuts: A Heart Nut to Crack

"Study Concludes that Eating Nuts Can Cut the Risk of Heart Attack," read the headline in The New York Times last spring.

Could nuts contain an antidote to high cholesterol levels? Yes. Should you eat more nuts? Not before you read the fine print.

In 1992, Joan Sabate and colleagues at California's Loma Linda University were examining the lifestyles of 31,208 Seventh-day Adventists, to see why they have lower rates of heart disease and some cancers than other Americans. (1)

Sabate noticed that Adventists who ate nuts more than four times a week were 38 percent less likely to die from heart disease than Adventists who ate nuts less than once a week.

But this kind of research doesn't prove that eating nuts caused the lower rate of heart disease. Maybe people who eat more nuts also do other things to reduce their risk.

So Sabate tried an experiment. He fed 18 healthy men two cholesterol-lowering diets. The nut diet was identical to the control diet, except that it substituted three ounces of walnuts for other fatty foods like meat and butter. That gave the nut diet less saturated fat and cholesterol and more unsaturated fat.

While the men were on the control diet, their cholesterol averaged 182. While on the nut diet, it averaged 160.(2) Does this show that walnuts lower cholesterol? Yes. But that's nothing new.

We've known for decades that when you eat unsaturated fat instead of the saturated fat and cholesterol in meat and butter, your cholesterol drops. In this case the source of the unsaturated fat happened to be walnuts. It could just as easily have been soybean oil.

Why did Sabate use walnuts? Probably because the walnut industry funded his study.

"Our research does not show that the way most Americans eat nuts, as a salty snack in addition to a high-fat diet, is good for your heart," says Sabate.

1 Archives of Internal Medicine 152:1416, 1992.

2 New England Journal of Medicine 328: 603, 1993.