What Astronauts Can Teach Us About Bone Health

Approaching the 43rd anniversary of Apollo 13, Dr. Charles T. Price of Institute for Better Bone Health had the pleasure of meeting its Commander, and discussing of all things – bone health in space.

Recently, as Chairman of the Annual Meeting Committee of the American Academy of Orthopedic Surgeons, I had the opportunity to meet and have an extended conversation with one of America’s true heroes, retired Captain Jim Lovell. You’ll recall that he was commander of the Apollo 13 mission to the moon that almost resulted in tragedy. He is an engaging and unassuming person who is helping the Chicago planetarium –where the conference took place - with all sorts of projects. We talked about several things, and then we got around to bone loss during weightlessness of space travel. When he learned of my work during medical school in Houston, Captain Lovell said that he had been the “human guinea pig” for some studies of calcium loss in space. The diet they fed him was terrible, but he had to stick to it strictly for two weeks while every drop and particle of body waste was collected and analyzed. At that point, I had to take partial credit for his terrible diet was undoubtedly very low in salt.a

Back when I was a second-year medical school student at the Baylor College of Medicine, my Chief Resident was a young doctor named Don Griffith, M.D. For those training to become doctors like myself, Chief Residents can be like your big brother or big sister, or they could become your worst nightmare.

Chief Residents in surgical specialties have been through eight or nine years of grueling education and training, yet they are close enough in age and experience to understand what you’re going through as a young med student. While some Chief Residents act like powerful dictators, most are helpful to everyone up and down the ladder.

TV shows like Grey’s Anatomy often portray a Chief Resident as doing neurosurgery, fixing a heart valve, and delivering a baby all in the same show, but that’s not reality. While no doctor is that versatile, the TV shows do capture the warm and close relationship between an inexperienced medical student and an effective Chief Resident. Don Griffith was one of those amazing Chiefs who took time to teach lowly medical students like myself what we needed to know.

Dr. Griffith’s specialty was in urology. One time he told me that he was doing research on how to prevent kidney stones in paralyzed patients. Back in the late 1960s, when I was in med school, the Baylor medical campus was—and still is—the home for the Texas Institute for Rehabilitation and Research (TIRR), which specialized in the treatment of spinal cord injury. The spinal cord injury patients were having problems with kidney stones, which led to kidney infections and sometimes death.

Don had a strong hunch that calcium in the urine—which causes kidney stones— was influenced by dietary sodium intake. He believed a low salt diet might help prevent kidney stones, which was a stunning concept at the time.

The Baylor College of Medicine was located in Houston, which was also the headquarters of NASA’s Manned Spacecraft Center. Remember, the late Sixties was the height of the manned space program, and the United States was poised to send the first man to the moon in the summer of 1969. Don had some contacts with the physicians who looked after the astronauts, and one of the issues they faced was how weightlessness in space could weaken the bones of the astronauts or cause kidney stones like patients who had been recently paralyzed.

Don explained to me one day that when the body rids itself of excess sodium in the urine, that process probably causes calcium to be flushed out of the body with the sodium. This creates a high calcium content in the urine, which depletes the bones of calcium and accounts for why paralyzed patients lose a great deal of bone mass in the first few weeks after a severe accident rendered them paraplegic.

Don theorized that a low sodium diet could prevent kidney stones, and if that was true, then a low sodium diet might also help prevent the bone loss caused by being paralyzed—or caused by weightless in space. This was heady stuff for a young medical student, so I asked Don if I could help him with his research. He was happy to have someone take an interest in his work and give him a hand.

Even though this was a volunteer project for me, I fully believed I was taking part in exciting research that could make a big difference. I went to the lab and tended to several animals on special diets. When the time came for studying the bones, I helped measure the calcium content in the ash after the bones were cremated. This was a good education about bone minerals and the relationship to dietary habits.

After my second year of medical school, other demands on my time became too great to continue helping Don, but my mentor doggedly continued his research and went on to an illustrious career as a faculty member at Baylor College of Medicine. Dr. Griffith subsequently published dozens of innovative research papers and became one of the world’s leading authorities on kidney stones.

Two of Don’s earliest papers were published the year I graduated from medical school and demonstrated that low sodium diets could reduce the urinary calcium levels in patients with paralysis or weightlessness. But what his research was really saying was that too much salt in foods was bad for bone health. That’s been proven by many later research studies and I feel fortunate to have been involved in the first studies that made the connection.

Research since 1971 has shown that too much salt is bad for a lot of things, especially hypertension. Some salt is OK but almost all Americans get entirely too much because it tastes so good. One way to combat too much salt is to increase intake of potassium or calcium. Extra calcium will replace the calcium that’s lost in the urine with the salt, but too much calcium also increases the risk of kidney stones and heart attacks. That’s why Institute for Better Bone Health only uses 500 mg of calcium in Silical 1 – part of Silical® System - when many other products have twice that amount, or more. Some calcium supplementation is helpful, and the type of calcium in Silical 1 is consistent with good absorption so there aren’t peaks of calcium in the blood from too rapid absorption. Read “Pass On The Salt for Better Bone Health” for more information about salt and bone health, and additional tips to reduce your salt intake.

It’s possible to get too much potassium from supplements so the best way to increase potassium is dietary with consumption of more fruits and fruit juices or vegetable juices. Potatoes also have a lot of potassium. The Alkaline Diet (which emphasizes fresh fruit, vegetables, potatoes and other root vegetables) is high in potassium, and that may be more important than the alkaline aspect of the diet.

I don’t know whether astronauts still have low salt diets, but I’d suspect that they have modest amounts of salt along with healthy portions of dried fruits and a little bit of calcium supplementation.

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