This month, Dr. Sydney Spiesel discusses the pitfalls of a soy-rich diet, dads' baby blues, a new treatment for recurrent urinary tract infections, and the flaws of asthma puffers. Click here and here for the last two columns.
Soybeans: Not entirely good for you?
The bean: One of Henry Ford's better contributions was the soybean. The automaker promoted the bean as a food crop and a material for products as diverse as plastics, printing inks, and fibers—sometimes he wore a necktie made out of soy-derived fabric. Presently, America grows about 83 million tons of soybeans annually, worth about $12 billion. When it comes to food, soy is everywhere. It's inexpensive, a meat substitute, and a high-quality, complete protein. Is there a downside? Maybe. There are at least three potential problems in a soy-rich diet.
The thyroid: Soy proteins themselves seem fine, but other plant-derived ingredients in soy food products may not be. One worrisome bunch are the isoflavones, natural chemicals whose health benefits have been promoted because they are antioxidants. The problem with soy isoflavones is that they can inhibit the production of the thyroid hormone, potentially leading to hypothyroidism, which irreversibly arrests mental development when it occurs in infants. Soy baby formulas are supplemented with a little extra iodine, which solves the problem for babies with normal thyroid glands. But soy-formula-fed babies with inactive glands may need extra thyroid hormone, since the results of hypothyroidism are so disastrous. Soy isoflavones don't pose a problem for adults.
Sex hormones: Another problem is that soy isoflavones act in the body like estrogens—female sex hormones. This effect is small but detectable. No harmful differences were shown in studies comparing post-menopausal women whose diets are rich in soy with similar women whose source of protein is largely dairy. Another retrospective study looked at about 800 adults ages 20 to 34: When they were infants, about one-third of the group had been fed soy formula, and two-thirds had been given cow milk formula. Again, the data suggested little difference in outcome. However, it was surely too early in the reproductive lives of many of the subjects to be certain, and there were not enough subjects to fully answer some of the more subtle questions about reproduction and endocrinology. It would be wonderful if the authors of this paper could go back to their study population in another 10 years to see what the further passage of time revealed.
The heart: The final concern is a subtle one that might not apply to humans at all but nevertheless makes me a little nervous. The FDA and the American Heart Association for some years recommended that a diet should include soy because it's good for the heart. But they've now backed away from that position, because there is little evidence that the modest lowering of cholesterol promoted by a soy-rich diet makes any real difference. On the contrary, there is a recent disquieting study in male mice that were genetically programmed to develop a form of heart disease. (Females are relatively resistant to the effects of the defective gene.) Susceptible mice that were fed a soy-based diet showed heart deterioration and went on to heart failure—while dairy-fed mice did not.
Conclusion: We have no idea if this observation applies to humans or why soy had this effect on the mice, but the study makes me hesitant to recommend a soy-rich diet, especially for people at special risk for heart disease. For myself, I'll stick to the little shreds of tofu in my moo shu beef.
Papa's new baby blues
The condition: Maternal depression following the birth of a baby is estimated to affect between 8 percent and 25 percent of women in the first year after giving birth (the broad estimate reflects the range of criteria for depression applied by different researchers). Now it's becoming clear that postpartum depression affects fathers as well.
The new research: In an interesting study reported in this month's Pediatrics, James Paulson and Sarah Dauber of Eastern Virginia Medical School, and Jenn Leifermann of the University of Colorado's School of Medicine in Denver looked at a national sample of more than 5,000 two-parent families. The research team interviewed mothers and fathers nine months after a baby's birth, using a standard questionnaire to look for symptoms of depression. They found significant symptoms in 14 percent of the mothers they studied—and in 10 percent of the fathers. A similar British study looked at about 25,000 mothers and fathers eight weeks after the birth of a child and identified signs of major depressive illness in 10 percent of mothers and 4 percent of fathers.
The findings: These studies concentrated on what PPD, the causes of which remain obscure, means for children. The American researchers measured how well depressed parents followed standard pediatric advice. They found that depressed mothers were less likely to engage in healthy feeding and sleep practices than mothers who were not depressed, and that depressed mothers and fathers were both less likely to read or tell stories to their babies or give them other enrichment. The British researchers studied children at age 3 and a half. They found that the children of fathers who had been depressed in the first two months of their baby's life were twice as likely to have emotional and behavioral difficulties as the children of fathers who weren't.
Conclusion: While horrifying, dramatic cases of PPD get plenty of attention, we tend to neglect the smaller incremental harms that happen to many children. This research is a wakeup call to pediatricians and other practitioners to be alert to the signs of depression in new parents, and to intervene.
Hope for recurrent UTIs
The problem: About one in 100 children suffer from a structural abnormality in the bladder wall that can lead to recurrent urinary tract infections. The problem prevents the muscular wall of the bladder from acting as a one-way valve when the ureters (tubes) carry urine from the kidneys into the bladder. If the valve malfunctions, then infected urine can get into the kidney, potentially leading to kidney damage, loss of kidney function, and chronic high blood pressure.
The traditional treatments: There are two traditional methods for preventing recurrent UTIs, each of which has drawbacks. Long-term antibiotics can suppress bacterial growth, but the underlying condition isn't cured, just treated, and the risk of repeat infection is high if treatment is briefly neglected. Extended treatment also may encourage bacteria that cause infections to become resistant to antibiotics. The other traditional treatment is open abdominal surgery on the bladder, a very delicate procedure that requires a skilled urologist and often extended postoperative hospital care.
The new treatment: Now there's a third option: In a recent paper in the journal Pediatrics, Drs. Richard Yu and David Roth of the Baylor College of Medicine describe successfully treating children by plumping up the tissue surrounding the ureter at the point it enters the bladder. They passed a cystoscope (a tiny instrument that allowed them to look and work inside the bladder) through the urethra of the anesthetized patient, identifying the point where the poorly functioning ureter entered the bladder, and injecting a thick gel just below the surface to plump up the region around the too-open mouth of the ureter to make it into an efficient one-way valve. The procedure, which doesn't require hospital admission and takes about 15 minutes, was performed on 120 children between 6 months and 15 years of age. It was 90 percent successful after one (or occasionally two) treatments, with no significant complications (two kids briefly had flank pain).
The advantages: The gel Yu and Roth injected (called Deflux) is composed of dextran, a product made of sugar, and hyaluronic acid, a material found throughout the body that helps lubricate joints, plump up umbilical cords, and stabilize the eye's fluid contents. The advantage of this material (which is not derived from animals) is that it is nonirritating, nonallergenic, and is slowly and naturally replaced in the injection site with the body's own collagen.
Conclusion: It is not clear yet whether the effects of Yu and Roth's treatment will be permanent. But some adult patients treated in the same way continued to do well two to five years afterward. A similar treatment, not licensed in the United States, is being tried for stress incontinence, a condition that affects about 15 percent of adult women. The new recurrent UTI treatment seems to be an impressive advance; if the procedure lives up to its promise in future studies, it may well become the major mode of treatment.
How do you know when your asthma puffer needs a refill?
The puffer: For most patients with asthma or the set of related conditions filed under "reactive airway disease," the mainstay of treatment is the metered-dose inhaler. This mechanism, which everyone calls a puffer, is a sealed pressurized container with active medication and a propellant to pressurize the medicine and blow it out as a superfine mist whose particles can be inhaled deep in the lungs. Puffers have been in use for, surely, 50 years and are largely unchanged in design, though we've gotten more sophisticated about what medicines we tuck into them and recently changed the propellant to one that doesn't destroy the ozone layer.
Typically, patients use puffers to deliver anti-inflammatory drugs, which calm the inflammation inside the lungs that's the underlying cause of their breathing problem, and bronchodilators. The latter drugs carry air deep into the lungs and cause the tightened smooth muscle in the wall of the air passages to relax. They also calm the overactive mucus-producing cells present in the lining of the air passages. Patients love puffers containing bronchodilators because they work quickly and relieve the struggle to take a breath. I and many doctors hate them because patients reach for them rather than using anti-inflammatory medicines, which actually treat their problem instead of just the symptoms. None of the puffers contains both types of drugs, and there is good evidence that the ones with bronchodilators, especially if used alone on a regular basis, contribute to inflammation—ultimately making things worse.
Running on empty: Now it turns out that there is another problem with puffers: Patients don't really know when the containers are running low on medication. A recent paper by Nancy Sander and colleagues of the Allergy & Asthma Network Mothers of Asthmatics point out that the puffer provides no clue of how many doses have been used and how many are left. Patients often try to figure out whether a container is empty by shaking it or spray testing. Neither method is reliable, because once the stated number of puffs has been used up, the quality of the puffs will begin to vary, with a decreasing amount of medication delivered. Doctors used to recommend floating the puffers in water to see what's left in them, but that's also unreliable and can screw up the mechanism. In fact, the only reliable way to know how many good puffs you've got is to keep track rigorously, which almost nobody seems willing to do, despite the potentially lethal consequences of running out of this medication.
Conclusion: Sander and her co-authors argue persuasively that puffer manufacturers should add an automatic dose-counting mechanism. I agree! Meanwhile, I will do my best to remind my patients to keep track of the number of doses used. And I will continue to prefer to replace anti-inflammatory puffers with DPIs—dry powder inhalers that allow the patient to inhale the anti-inflammatory medication as a wisp of ultra-fine dust, doing away with the liquid pressurizing propellant and thereby removing an inactive but potentially irritating ingredient from the mixture the patient inhales. Besides, unlike the metered-dose puffers, DPIs have a little window that tells you when they are empty. So far, no fast-acting bronchodilator DPIs have appeared on the market. I hope one comes out soon.