SMOKING AND BONE HEALTH
Claudia Wallis sums up issues with bone health and calcium metabolism well in “A diet for better bones” [The Science of Health]. She mentions the likely deleterious effects of excessive alcohol and coffee consumption in the article. To this list I would add cigarettes, in any quantity and at almost any time of life.
A common part of my practice as a neurosurgeon was the evaluation of patients with osteoporosis and the performance of spine surgery, including fusion. I quickly saw that almost all of my osteoporosis patients had smoked, although many of them initially denied having a history of cigarette smoking until specifically asked if they had smoked as a teenager. Even a short history of cigarette smoking during the period of bone growth and ossification – adolescence and early adulthood – was correlated with a significantly increased risk of osteoporotic fractures in late adulthood.
Similarly, the rate of successful spinal surgery—particularly discectomy and fusion—in active smokers was significantly lower than in nonsmokers, so I would postpone elective surgery until the patient has been discharged from cigarette smoke for at least four – and ideally six – weeks. Over the decades that followed, numerous studies validated my anecdotal observations.
As Wallis notes, vitamin D supplementation is probably of little benefit to most people who want to avoid osteoporosis. But quitting smoking – or better yet, never smoking – is certainly very beneficial.
DANIEL SPITZER Piermont, NY
LESS TRAVELED METABOLIC PATH
I loved “The human engineHerman Pontzer’s article on rigorous experiments that determine trends in human metabolism adjusted for age and lean body mass. The “Measuring Metabolism” box shows these data in two graphs, and the high degree of scatter in their respective regression curves leads to even more interesting questions.
Each scatter dot represents a single human being who is probably not “average”. Can the scatter explain why some people have a harder time losing weight or why a particular diet may not work for everyone? How is it related to genetics versus environment? Is it ethical to make health recommendations based on a sample mean when those outside the regression curve could be harmed? Additionally, new cancer therapies tailor treatments to an individual’s genetics. Are these considerations applied to dietary and metabolic studies?
BRAND G. KUZYK Regents Professor of Physics, Washington State University
I was surprised that Pontzer’s article on human metabolism made no mention of gut microbiota. Each of us coexists with a complex intestinal ecosystem that contains more organisms than there are cells in our body. Recent findings have clearly shown that the gut microbiota influences many aspects of our physiology, from immune function to mental health, and alterations induced by widespread use of antibiotics and highly processed foods most likely play a role. essential in explaining the obesity epidemic. . The gut microbiota is also the filter through which all of our food is processed, linking it inextricably to human metabolism. It’s not just “we” who use the calories we consume, which renders the “calories in, calories out” formulation cited by Pontzer incomplete.
IRA S. NASH Scarsdale, NY
PONTZER ANSWERS: Understanding the considerable variability we observe between individuals in their daily energy expenditure is the next frontier of metabolic research. We now have a good idea of how body size, fat percentage, lifestyle, and age affect the calories we burn each day, but as readers Kuzyk and Nash point out, there are many unexplained variations. The extent to which these differences reflect genetics or environment is not well understood at this time. Our microbiome may well be an essential piece of the puzzle. However, evidence on this front is currently scarce. Time and more studies will tell.
We generally don’t find that a “fast” or “slow” metabolism (burning more or less energy than we would expect for a person’s height and age) predicts weight gain or fat loss. ‘obesity. I suspect that the metabolic variation we see tells us something about overall bodily function and health, but these possible connections have yet to be tested..
“The universe is not locally realby Daniel Garisto reports how the Bell test was used to rule out the existence of hidden variables, invisible factors that could explain quantum mechanical phenomena while preserving local realism. But I’m still puzzled as to why the answer to the hidden variables question hasn’t been declared unsolvable by this technique.
Garisto says “any prior physical connection between components, no matter how far in the past [emphasis mine], has the potential to interfere with the validity of the results of a Bell test. He then describes a “cosmic bell test” in which researchers used stars “distant enough” that light from one would not reach the other for centuries. But assuming the big bang and cosmic inflation are true, doesn’t that mean there is an inevitable loophole in each Bell test because everything was physically connected in the distant past?
GARY RECTOR Cave Creek, Arizona.
GARISTO’S RESPONSE: There have been other Cosmic Bell tests since the one I described in my article, including one that used light from quasars billions of light years apart. Rector is correct that even these tests only date back to this day. As he suggests, this implies that the big bang remains an inevitable escape. It is worth considering what such a loophole-sized theory would presuppose: that the hidden variables were encoded at the very beginning of time and space, setting everything in motion deterministically until the end of space-time..
Superdeterminism, as the idea is called, might save the local realism of quantum mechanics, but it strips the universe of chance in favor of a conspiratorial approach to experiments. Everything we can measure suggests that quantum mechanics is correct, that local realism is wrong. It is worth being aware of superdeterminism as a possibility. But believing things because they’re impossible to rule out is a bad way to approach science — or, for that matter, anything else..
Bumblebees seem to be “playing”, according to the study reported in “Bee-Ballby Grace van Deelen [Advances]. This raises a question: are bees individually intelligent? And the ants? Within a colony, these insects constantly exchange information in the form of pheromones and other chemicals. A colony of bees or ants manifests more intelligence than would be expected by adding together the intelligence of the individuals.
VAN SNYDER La Crescenta, California.
In “Primal Soupby Clara Moskowitz [March 2023], the “Quark Soup” box should have indicated that the sPHENIX and STAR detectors at Brookhaven National Laboratory each have a powerful magnet at their core, not a powerful superconducting magnet. Only the sPHENIX magnet is superconducting.