September 22, 2012 – 12:59 pm
Vitamin D is often referred to as the “sunshine vitamin” because the first step in making it occurs in the skin and is stimulated by the ultraviolet light in sunshine. This produces a preliminary form called vitamin D3, which is one of the common forms of vitamin D found in food and in supplements. The next step occurs in the liver, with a final step to make fully active vitamin D occurring mainly in the kidneys. The form made in the liver goes by the scientific name 25-hydroxy-vitamin D. This appears to be the storage form of the vitamin, and is also the form of vitamin D measured in blood tests for the vitamin.
Blood levels of vitamin D in people living in northerly countries such as Canada and the Scandinavian countries are measurably much lower in the winter than in the summer. This led medical researchers in Norway to investigate whether this difference could be related to various measures of health – and it was. Among other associations, they saw that people diagnosed with cancer of the breast, colon or prostate gland had a 15% – 25% lower risk of dying if they were diagnosed in summer or fall, compared to those diagnosed in winter or spring. This led to many more studies around the globe looking at vitamin D and cancer, and again higher levels correlated with better outcomes for many patients.
The latest study of this type comes again from Norway and it looked at vitamin D levels in patients diagnosed with cancer of the breast, lung and colon, as well as the immune system cancer called lymphoma. A strong point of the study was that over 650 people with these cancers were followed for a long time, from 1984 to 2004. Their vitamin D levels were tested within 90 days of their diagnosis. The researchers adjusted for the seasonally varying levels of the vitamin in their statistical analysis of the outcomes. For example, a value of ‘70’ in the winter might be equivalent to 100’ in the winter.
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Doctors recommend all those 50 year of age or older to be screened preventatively for colon cancer. There are three distinct ways of doing this: colonoscopy, sigmoidoscopy and ‘virtual colonoscopy.’ The first method is the most involved and still appears to be the most sensitive approach. Sigmoidoscopy is simpler but only surveys the last one-third of the colon (large intestine); however, over half of all colon cancers are in this area, so it is still considered a valuable exam. Both these methods involve the insertion of a flexible viewing scope past the anus and into the colon.
The ‘virtual colonoscopy,’ however, is non-invasive: pictures are taken from the outside. It is actually the technique called computed tomography (CT) applied to the colon. Computed tomography – sometimes called computer assisted tomography, CAT – can be described simply as a more accurate version of traditional X-rays, though there are various technical differences. So far, the CT method seems to be somewhat less sensitive than a real colonoscopy, yet can be a partial substitute for it in patients who are too sick or weak to tolerate a colonoscopy and the sedation it requires.
Both colonoscopy and it’s virtual counterpart require a patient to not have solid food the day before the procedure, and also to drink literally a gallon of a laxative solution. This thoroughly cleans out the intestines and makes for the best visibility of any potential tumors or pre-tumors, which are called polyps. Unfortunately, a minority yet substantial portion of people find they just can’t stand getting through this preparation routine. The sigmoidoscopy, on the other hand, is usually done without any laxative – but isn’t as thorough as the other two techniques.
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For decades now, doctors have urged patients hitting their fifties to get a colonoscopy once every five to ten years to check for colon cancer – a tumor in the large intestine. These are done by gastroenterologists, doctors who specialize in diseases of the digestive tract. In this procedure, a long, flexible viewing scope is inserted at the anus and is extended out progressively longer – further up into the colon – during the exam. Patients are under mild sedation, waking a short while later with no recollection of discomfort, perhaps just slightly sore. A simpler procedure for such a check is the sigmoidoscopy, which uses a shorter scope; sedation isn’t necessary for this exam. Although not seeing beyond the first third of the colon, the majority of colon tumors occur in that portion. Hence a sigmoidoscopy is still a valuable exam, but is not as thorough as a colonoscopy.
During either procedure, the doctor is looking for tumors but also for less serious growths called polyps. These are outgrowths of cells that may be precancerous or may be benign (non cancerous). The most common shape for a polyp is a bit like a mushroom, with a ‘stalk’ coming out of the intestinal wall and a roundish growth at the end of it. There are also flat polyps that bulge up slightly but are wider and have no stalk, hence being harder to see. To a doctor doing a colonoscopy, a stalked polyp sticks out like the proverbial sore thumb compared to flat ones. Whenever found and whenever possible, polyps are removed, since some will be precancerous. This isn’t known until after a pathologist looks at a sample under the microscope. Patients with a precancerous polyp will be recommended to have another procedure in three years, rather than the five to ten for those with no polyps or only a benign polyp.
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It’s not the most obvious thought: Look for early symptoms of a brain disease in the large intestine. Yet growing evidence shows this is exactly where to look for Parkinson’s disease, finding signs of it there years before the terrible trembling symptoms of the disease first appear. How did this come about?
Parkinson’s disease (PD) is named after British doctor James Parkinson who first described the condition in 1817. PD has been understood since the late 1800s as a disease of the central nervous system. Autopsies of persons with PD have for decades been known to contain distinct abnormalities in parts of the brain producing the important neurotransmitter called dopamine. These oddities are called Lewy bodies, for the doctor who first described them in 1913. But how to detect these abnormal signs of PD before the time of an autopsy?
Logically enough, doctors have used various kinds of medical imaging of the brain, attempting to capture a picture of Parkinson’s early warning signs. Unfortunately, computed tomography (CT) and magnetic resonance imaging (MRI) of PD patients’ brains appear normal. One type of brain imaging may aid in diagnosing PD if an abnormality is seen, but this is not an exclusive association. So, brain scans are mainly used to rule out other disorders that could cause similar symptoms but do show up in imaging, such as tumors and vascular abnormalities.
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