11/14/2007
Updates on a Vitamin and a Solar System
Last week I promised to look into a new study on vitamin D that seems to cast doubt on some of the benefits of the vitamin that we discussed two weeks ago. However, while I was checking out this work, Brian Trumbore called my attention to another study from the UK that suggests that vitamin D may help slow aging. One negative and one positive; I’m sure we’ll hear more on D in the future. Writing about anything to do with health is fraught with the possibility a contradictory bit of research will surface shortly.
I’ll get back to vitamin D shortly but first I have to report on something truly exciting, to me at least. Three years ago (9/8/2004), I mentioned the discovery a fourth planet orbiting the star 55 Cancri, a mere 41 light years away. With four planets orbiting this star I ventured the comment: “You can bet that this is one planetary system that will get lots of attention in years to come.” It has, not only since 2004 but also for the past 18 years and now the astronomers have announced they’ve found a fifth planet in 55 Cancri’s solar system.
Yes, it has taken 18 years of continuous observations at the Lick Observatory in California and at the W. M. Keck Observatory on Mauna Kea, Hawaii. The five planets around 55 Cancri have been detected by the “wobble” method in which painstaking measurements are made of the gravitational tug on the position of the star as the planets orbit around it. A report on the NASA Web site dated November 6 implies that one of the reasons it has taken so long to capture this fifth planet is that it takes 14 years for one of the other planets to complete one orbit around 55 Cancri. I’m thinking that perhaps the astronomers Debra Fischer and Geoff Marcy and their collaborators had to follow one complete orbit to pin down the effect of the newly discovered planet on the wobble.
Obviously, the position of the star at any moment is determined by the positions of the five planets as they all orbit the star, each planet pushing or pulling depending on its alignment with the other planets at that moment. To me it’s astounding that astronomers can measure a star’s position so precisely that they can eventually figure out that there have to be five planets to account for the data. And this for a star that’s over 200 trillion miles away from Earth.
If you wonder why all the excitement, hey, they’ve found a star with at least five planets. We only have 8 in our solar system now that Pluto has been demoted. Furthermore, this new planet happens to be in the “habitable” zone around 55 Cancri. It orbits the star in 260 days, not much different from our year of 365 days. It’s about 20 million miles closer to the star, but 55 Cancri is not as bright as our Sun. Being in the habitable zone of course brings up the possibility of life. The downside is that the planet is around 45 times larger than Earth and probably is more like Saturn in its makeup.
Though the planet itself is unlikely to harbor life, what about any moons? Moons would seem to be likely based on the fact that our own massive planets have large moons such as Europa and Titan. Moons in the habitable zone around our new planet orbiting 55 Cancri might have pools of water and a rocky surface. Life? I don’t expect to live long enough to read of moons being detected around any planet in a distant solar system, but I feel comfortable about predicting again that we haven’t heard the last of 55 Cancri and its companions.
Well, back down to our own sun and vitamin D. First, the possible bad news. Researchers at the National Cancer Institute analyzed the blood levels of vitamin D in some 17,000 subjects in a decade-long study following their health. After ten years, there was no apparent effect of vitamin D on the chances of dying from cancer, with one exception. For colorectal cancer, high levels of vitamin D correlated with a 72% reduced chance of dying from that disease. It’s not all negative news.
The study, to my knowledge, didn’t seem to invalidate the observations of reduced cancer risk related to latitude of the country of residence mentioned in my earlier column. There’s one big caveat about this new study, however. The vitamin D levels were measured at only one particular time in the lives of the participants in the study. This is admittedly a big problem that could skew the results, especially if the vitamin D levels change significantly with the seasons and exposure to sunlight. There’s more work to be done.
The more positive note is struck in a BBC article dated November 8 and headlined “Vitamin D ‘may help slow ageing’” that describes a King’s College London study of over 2,000 women of ages between 18 and 79. What they found was that, adjusting for the age of the participant, the women who had the highest levels of vitamin D had the longest telomeres in the DNA of their white blood cells.
We haven’t discussed telomeres in some time. Telomeres are sections of DNA that cap the ends of DNA strands. Telomeres generally get shorter as cells reproduce and are considered a marker of the age or imminent death of cells. White blood cells tend to divide/reproduce more rapidly if the body is suffering from inflammation. Thus the telomeres in white blood cells will get shorter more rapidly if inflammation is present. The King’s College study suggests that the vitamin D being associated with the longer telomeres is a sign that the aging process is slowed down by the vitamin in the blood. As with the other vitamin D study, however, there are caveats and there’s the possibility that some other factor is responsible for the longer telomeres.
OK, so much for the health front. Again, I’m sure there will be more research following up on the telomere shortening. I must admit that I feel it’s more likely that astronomers will find a sixth planet around 55 Cancri before we truly understand the role of vitamin D.
Allen F. Bortrum
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