Dear Doctor: Fracking just started near my Ohio hometown, and I remember reading about a connection to the risk of having a baby with low birth weight. I want to get pregnant, but now I’m worried. How close do you have to be to a site to be affected?

Dear Reader: "Fracking" is the common term for hydraulic fracturing, a drilling process that pumps fluid at ultra-high pressure deep into the earth. This fractures the underlying shale rock and makes the natural gas or oil that it contains available for extraction. There has been no end of controversy regarding the process in recent years, with vigorous debate over whether or not fracking causes air pollution, contaminates surface and groundwater, leads to earthquakes and plays a role in a range of health problems. Among the health questions that have been raised is whether the process affects birth weight among pregnant women who live near fracking sites.

Your question refers to a study published a few years ago in the journal Science Advances. The researchers, including one from UCLA, analyzed the outcomes of 1.1 million live births in Pennsylvania between 2004 and 2013. They compared the birth weights of infants born to mothers living at varying distances from active fracking sites, both before the extraction operations had begun, and after the wells became active. They found that women who lived very close to an active fracking operation -- within one-half mile -- had a 25 percent higher risk of delivering a baby of low birth weight than did women who lived at a distance of 2 miles or more.

The study found that babies born to women who lived more than one-half mile from a fracking site, but less than 2 miles away, were also adversely affected, but to a lesser degree. When researchers looked at women who lived at least 2 miles from a fracking operation, they found no signs of adverse health effects to newborns.

"Low birth weight" is the term used to describe an infant who weighs less than 5 pounds, 8 ounces at delivery. By contrast, the average healthy newborn weighs in at about 8 pounds. Low birth weight occurs most often in premature births, when the infant doesn’t have the full 37 weeks of gestation to grow and gain weight. Low birth weight is sometimes seen in full-term babies who failed to grow well during gestation due to issues with the mother’s health, the placenta or the baby’s condition. Multiple births also often result in smaller babies.

The reason low birth weight is a concern is that smaller babies are at greater risk of complications after delivery, including low oxygen levels, difficulty feeding, gastrointestinal problems and SIDS, or sudden infant death syndrome. Low birth weight has also been shown to be a risk factor for future health and developmental problems such as asthma, Type 2 diabetes, attention deficit disorder, learning disabilities and hyperactivity.

Although the study correlates proximity to fracking sites with low birth weight, it doesn’t explain what is causing these outcomes. The authors agree that more information is needed, and have said they hope their study will lead to further research.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: Your recent column about how potassium can help lower blood pressure was quite helpful, but when I looked into supplements, they turned out to be almost useless. Why is that? What foods should I be eating?

Dear Reader: Potassium is a mineral that plays a key role in the optimal functioning of nerves, muscles, fluid balance, and, as we wrote about recently, the regulation of blood pressure. Although it’s found in a wide range of whole foods, Americans’ ongoing love affair with highly processed and fast foods has led to diets that fall short of adequate potassium.

The most recent guidelines for daily potassium intake were released last March by the National Academies of Science, Engineering and Medicine. They recommend a minimum of 2,300 milligrams per day for healthy women, and 3,400 mg per day for healthy men. These newest recommendations are lower than those previously established in 2005.

Unfortunately, according to the National Institutes of Health, the majority of Americans get less than half the amount of the mineral that they need. It seems logical that, since you can boost your intake of just about any vitamin or mineral with a supplement, you should be able to do the same with potassium. However, it’s not that simple. Potassium has the potential to interact with a variety of medications, including blood pressure meds, diuretics and some common pain medications. Depending on the specific medication, it can result in potassium levels that are dangerously high or dangerously low. Too much or too little potassium can lead to muscle cramping, nerve problems, problems with cognition and potentially life-threatening heart arrhythmias. As a result, the U.S. Food and Drug Administration requires over-the-counter potassium supplements, including multivitamins, to contain less than 100 mg, which is a fraction of the recommended daily intake.

The good news is that by eating a diet that draws from a wide variety of whole and fresh foods, you can meet your daily potassium needs. Foods that contain high or moderate levels of potassium include fish like salmon, tuna, cod and snapper; most red meats; leafy greens like spinach and chard; black beans, pinto beans and white beans; avocados; bananas; apricots; potatoes; tomato sauce and tomato paste; watermelon; lentils; cantaloupe; yogurt; and coconut water. One quick and easy way to give a meal a potassium boost is with frozen spinach, which can easily be added to soups and stews and used as a side dish. Beans, beets and avocados make great additions to salads. Try swapping out sweet or salty ultra-processed snacks for cantaloupe or watermelon.

While you’re busy revving up your potassium intake, don’t forget to continue to be vigilant about salt. The American Heart Association wants adults to eat no more than 2,300 mg of sodium per day, and recommends we stick closer to a limit of 1,500 mg per day -- or less. This is particularly important for people dealing with high blood pressure, or those who are at risk of cardiovascular disease.

Although getting enough potassium without the help of supplements may seem daunting at first, deliberate food choices and just a bit of advance planning will get you into the zone.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: Is it true there’s lead and heavy metals in some brands of baby and toddler foods? My husband and I both work, and it’s hard to completely avoid using prepared foods.

Dear Reader: As working parents ourselves, we understand the challenge you’re facing. Once babies make the transition to solid food, it’s often a struggle to thread the needle between the ease and convenience of prepared foods and the satisfaction of knowing exactly what’s in that spoonful of homemade food headed for your baby’s mouth.

The debate about prepared versus homemade infant and toddler foods isn’t new, and it has led to the emergence of an ever-growing selection of boutique and organic options. But recent tests conducted by consumer advocacy groups and a leading consumer magazine have produced data that is giving some parents pause. Last summer, Consumer Reports revealed that its analysis of 50 packaged baby and toddler foods found a measurable amount of lead, inorganic arsenic or cadmium in each sample that was tested. Foods made with rice or sweet potatoes had a strong likelihood of testing positive for high levels of these heavy metals, according to the report. Among the surprises in the data was the fact that organic foods tested positive as often as the conventional products.

This report built upon data released two years ago by the Environmental Defense Fund, a consumer advocacy group. That study, which examined data collected by the U.S. Food and Drug Administration over the course of a decade, found that measurable amounts of lead were present in one-fifth of all nationally distributed infant and toddler foods.

Surprisingly, child-targeted products often contained higher levels of lead than adult products, with grape juice and mixed fruit juices the most likely to contain detectible levels. Although the exact reasons for the presence of these heavy metals is not yet known, contaminated soil, as well as manufacturing processes in a globalized food chain, are leading suspects.

Meanwhile, some manufacturers have taken issue with both the data and the conclusions of these reports. They point out that the amounts of lead found in the FDA data all fall within the agency’s guidelines. The Consumer Reports data has been faulted for failing to specify the exact amounts of heavy metals that have been detected.

The good news is that these reports, which have put a spotlight on the issue, are helping to catalyze relevant policy changes at the FDA. We think this is important because the contaminants under discussion can result in serious harm to a child’s health and development, particularly to the developing brain and nervous system.

Our advice, and this has as much to do with general health as it does with potential contaminants, is to minimize the use of processed and packaged baby and toddler foods as much as possible. Fruit juices and rice cereals, which are highlighted in the reports, really aren’t ideal foods for young children. Instead, try to focus on a diverse diet of whole, unprocessed foods. With time and planning (and a good food processor), you’ll give your child a solid nutritional foundation and earn yourself some peace of mind.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)