Older people may be at increased risk of premature death if they have low levels of bicarbonate, a main ingredient in baking soda, in their blood, a new study suggests.
In the study, researchers examined nearly 3,000 relatively healthy adults ages 70 to 79 over a 10-year period. During this time, about half of these people died from natural causes. But the adults with low levels of bicarbonate in their blood were nearly 25 percent more likely than the adults with normal or high levels of bicarbonate in their blood to die during the study period, the researchers found.
The reason for the link isn't exactly clear, but it may have to do with the ill effects of having slightly acidic blood, the researchers said. Bicarbonate, a base, is a natural byproduct of metabolism that the body uses to regulate the pH level of the blood. Bicarbonate counters carbon dioxide and other acidic byproducts of eating and breathing to keep the blood at a neutral pH.
Another possible explanation is that the low levels might point to underlying (and undiagnosed) kidney problems, the researchers said. Given that it's easy to test for bicarbonate in the blood, it may be prudent for doctors to monitor bicarbonate levels in older adults to reduce their risk of premature death, the researchers said. [Extending Life: 7 Ways to Live Past 100]
The study, led by Dr. Kalani Raphael of the University of Utah in Salt Lake City, appears this week in the Clinical Journal of the American Society of Nephrology.
Scientists have long understood the importance and basic mechanisms for regulating blood pH. As aerobic organisms, humans breathe in oxygen and use this chemical with food nutrients to create energy, with the byproduct being the slightly acidic chemical carbon dioxide. Digestion also produces acids such as sulfuric acid. Dangerous levels of acid could build up in the bloodstream without a mechanism to neutralize or eliminate it.
Many organs produce bicarbonate, which can buffer the acid, and the kidneys excrete excess acid through urine.
The new study found only an association, not a cause-and-effect relationship, between bicarbonate levels and the risk of early death, the researchers noted. They could not determine whether the low levels of bicarbonate in the blood contributed to the deaths or were an indicator of an underlying medical problem that could have contributed to these people's deaths.
Previous studies have found that low bicarbonate levels are associated with declining kidney function over time, even in people without kidney disease, and this increases the risk of death, including cardiovascular death, Raphael told Live Science. Low bicarbonate levels are also associated with inflammation and a loss of bone mineral and muscle mass, "so these factors may play a role," Raphael said.
Dr. Michael Emmett, chief of internal medicine at Baylor University Medical Center in Dallas, who was not part of the study, added that kidney function declines naturally with age, making it harder for the body to excrete acid loads derived from the diet. Acid retention reduces bicarbonate levels, and even low to normal levels may contribute to a variety of age-related disorders, such as osteoporosis, reduced muscle mass and strength, and kidney stones, he said.
The findings, if confirmed in larger studies, may provide primary care doctors with a simple measurement to help identify patients who have an elevated risk of early death. However, the remedy to reduce this risk isn't yet clear.
Doctors who find low levels of bicarbonate in a patient's blood might want to look for the root cause, to see if an underlying condition is responsible. They also might want to have patients increase their bicarbonate levels through the diet — but that doesn't necessarily mean eating more baking soda or the baking goods that might contain it, Raphael said.
Older people in general might benefit from a diet with less meat and more fruits and vegetables, Emmett said. Meat, which is rich in protein and thus amino acids, increases the body's acid load, and this could be a challenge for aging kidneys to excrete. But when plant-based foods, particularly fruits, are digested, they produce bicarbonate. This, in theory, could raise bicarbonate levels in the blood.
This simple premise of pH regulation has given rise to the alternative medical practice of consuming baking soda (sodium bicarbonate) or other sources of bicarbonate, which is purported to slow the aging process and cure cancer. But there is no evidence to support such claims, scientists say. [8 Tips for Healthy Aging]
Worse, consuming too much baking soda can lead to health problems such as a perforated stomach, high blood pressure due to the sodium load, and possibly kidney stones from producing excess calcium in the urine, Emmett said. Instead, potassium bicarbonate might be a better alternative to baking soda, but it should be taken only under a doctor's supervision, he said.
"We don't know for sure if raising low bicarbonate levels into the normal range with baking soda or taking baking soda if your bicarbonate levels are normal improves health," Raphael said. "People with kidney, heart, lung and liver diseases, and women who are pregnant, should never self-medicate with bicarbonate or baking soda."
But no disrespect to baking soda — it gets out stains, deodorizes closets and refrigerators, whitens teeth, and makes fluffy baked goods. That ain't too shabby.
Follow Christopher Wanjek @wanjek for daily tweets on health and science with a humorous edge. Wanjek is the author of "Food at Work" and "Bad Medicine." His column, Bad Medicine, appears regularly on Live Science.