June 21st, 2011 by Harriet Hall, M.D. in Health Tips, Research
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Science has found no evidence that vaccines cause autism; but the true cause(s) of autism have not yet been determined. So far the available evidence has pointed towards a largely genetic cause with possible interaction with environmental factors. A new study supports that interpretation. It also supports previous evidence that autism is triggered prior to birth, rather than at the time of vaccinations.
Schmidt et al. published a study in Epidemiology on May 23, 2011, entitled “Prenatal Vitamins, One-carbon Metabolism Gene Variants, and Risk for Autism.” It was a population-based case control study of 566 subjects comparing a group of autistic children to a matched control group of children with normal development. They looked at maternal intake of prenatal vitamins in the 3 months before conception and the first month of pregnancy, and they looked for genotypes associated with autism. They found that mothers who didn’t take prenatal vitamins were at greater risk of having an autistic child, and certain genetic markers markedly increased the risk. There was a dose/response relationship: the more prenatal vitamins a woman took, the less likely she would have an autistic child. There was no association with other types of multivitamins, and no association with prenatal vitamin intake during months 2-9 of pregnancy.
They had a large sample size, and they tried to eliminate confounders. They looked for these potential confounders of the association between prenatal vitamin intake and autism: child’s sex, birth year, parent-reported race/ethnicity, family history of mental health conditions, paternal age at child’s birth, maternal age at child’s birth, education, prepregnancy body mass index (BMI) category, cereal intake from 3 months before through the first month of pregnancy, cigarette smoking, alcohol consumption, and residence with a smoker during the period 3 months before pregnancy to delivery. Only maternal education and the child’s year of birth proved to be confounders. They adjusted for these two factors in their analyses. A weakness of their study is that it depends on patient recall long after the fact. Also, it did not attempt to gather any diet information.
Mothers of children with autism were less likely to report taking prenatal vitamins (odds ratio 0.62). Having certain genotypes increased the odds that a vitamin-omitting woman would have an autistic child. Children with the COMT 472 AA gene were at increased risk of autism. If their mothers took prenatal vitamins, the odds ratio for the risk of autism was 1.8; if their mothers didn’t, the odds ratio jumped to 7.2. This suggests that the maternal-fetal environment can magnify the effects of a child susceptibility gene. There was an association with certain maternal genes as well: those odds ratios went as high as 4.5.
The association was robust. The authors think Read more »
*This blog post was originally published at Science-Based Medicine*
June 8th, 2011 by PJSkerrett in Health Tips
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The crumbling Food Pyramid and its hip successor (MyPyramid) fell into oblivion yesterday, eroded by the stinging winds of science. Their replacement? A quartered plate called—wait for it—MyPlate that was designed to visually convey the elements of healthy eating to Americans of all ages.
The new icon consists of a white plate divided into four segments: green for vegetables, red for fruits, orange for grains, and purple for protein. Dairy has a prominent place, sitting where a glass of water should be. The hope is that the plate will nudge Americans away from meals dominated by meat and starch and towards meals made up mostly of plant-based foods.
The original Food Guide Pyramid debuted in 1992. It was built on shaky scientific ground. Over the next few years, research from around the world chipped away at the healthy eating message in the pyramid’s base (refined carbohydrates), the middle (meat and milk), and the tip (fats).
The Pyramid got an extreme makeover in 2005. Read more »
*This blog post was originally published at Harvard Health Blog*
June 5th, 2011 by Dr. Val Jones in Opinion
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I just learned (yes, I’m a little late to the party) about the Body Shop anti-barbie controversy from a post on Facebook. The ad to the left has been banned from most countries, because it was believed to be in bad taste. For me, it raises some very interesting questions.
First of all, it’s been my experience that the media has been relentless in its portrayal of feminine beauty as being a dress size zero. This is an unattainable goal for most of us, and a very narrow view of what is truly attractive and physically healthy. I can’t imagine how many young girls feel deeply flawed when they compare themselves to Barbie et al. If unchecked, that self-doubt and insecurity can become a lifelong self-esteem issue or worse. Eating disorders are becoming more and more common, and carry with them the highest mortality rate of any mental illness.
That being said, I’ve often had mixed feelings about the few “love your body as it is” campaigns* that have tried to push back against the rail-thin ideal. While we all have different body types, it’s still not healthy to be obese. Just as our favorite pets are born with different natural shapes (Chihuahuas, Whippets, Golden Retrievers, and Great Danes), we humans are different sizes too. But that doesn’t mean it’s “ok” to be excessively fat. Read more »
May 30th, 2011 by Mark Crislip, M.D. in Health Tips
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It is hard to get infected. The immune system is robust and has a multitude of interlinking defenses that are extremely efficient in beating off most pathogens. Most of the time.
Fortunately, it is a minority of microbes that have evolved to be virulent in humans. Bacteremia is common with our own microbiome. When you brush or floss, bacteria leak into the blood stream:
We identified oral bacterial species in blood cultures following single-tooth extraction and tooth brushing. Sequence analysis of 16S rRNA genes identified 98 different bacterial species recovered from 151 bacteremic subjects. Of interest, 48 of the isolates represented 19 novel species of Prevotella, Fusobacterium, Streptococcus, Actinomyces, Capnocytophaga, Selenomonas, and Veillonella.
but with a good immune system, low virulence bacteria and no place to go, unfortunately the bacteria rarely cause infections.
Even heroin users rarely get infection. Heroin is a rich melange of bacteria and, on occasion, yeasts (I hate to say contaminated, since avoiding microbes is hardly a worry of heroin manufacturers), and the water used for injection is rarely sterile, yet infections are relatively rare despite the filth in which many heroin users exist.
I used to be somewhat fatalistic about hospital acquired infections. However, as the institutions in which I have worked have proven, almost all infections in the hospital are preventable if the institutions aggressively pursue high standards of care.
There are many systems in place in society to prevent infections: flush toilets, good nutrition, public health, vaccines, antibiotics, good hygiene, and an understanding of disease epidemiology, and I suspect people forget there are bugs out there that are pathogenic, just waiting to sicken and kill us. At least a couple of times a year I see patients come into the hospital, previously healthy, who rapidly die of acute infections. But for most people, most of the time, it takes a lot of effort to get an infection.
From my perspective we are Charlie Chaplain on skates , mostly unaware of the infections that awaits us if we do something silly, Read more »
*This blog post was originally published at Science-Based Medicine*
May 19th, 2011 by Jessie Gruman, Ph.D. in Health Policy, Health Tips
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Only one in 10 respondents to a national survey could estimate how many calories they should consume in a day.
Seventy-nine percent make few or no attempts to pay attention to the balance between the calories they consume and expend in a day.
These and other piquant findings from the online 2011 Food and Health Survey fielded by the International Food Information Council Foundation (IFIC) struck home last week as I smacked up against my own ignorance about a healthy diet and the difficulty of changing lifelong eating habits.
The confluence of my failure to gain weight after cancer treatment and a blood test suggesting pre-diabetes meant that as of last Tuesday, I have been on an eat-specific-types-of-food-every-hour-and-write-it-down regimen. And despite a lifetime of recommending that people change their behavior to become healthier, I am frustrated as I try to follow my own advice. I am bewildered about what I’m supposed to eat. Finding it, preparing it and then eating it at the right time requires untold contortions and inconvenience. Writing it all down is tedious. I don’t have time for this – I have a job, obligations. Read more »
*This blog post was originally published at Prepared Patient Forum: What It Takes Blog*
