Organic produce and meat typically isn't any better for you than conventional varieties when it comes to vitamin and nutrient content, according to a new review of the evidence.

But organic options may live up to their billing of lowering exposure to pesticide residue and antibiotic-resistant bacteria, researchers from Stanford University and the Veterans Affairs Palo Alto Health Care System found.

"People choose to buy organic foods for many different reasons. One of them is perceived health benefits," said Dr. Crystal Smith-Spangler, who led the new study.

"Our patients, our families ask about, 'Well, are there health reasons to choose organic food in terms of nutritional content or human health outcomes?'"

To try to answer that question, she and her colleagues reviewed over 200 studies that compared either the health of people who ate organic or conventional foods or, more commonly, nutrient and contaminant levels in the foods themselves.

Those included organic and non-organic fruits, vegetables, grains, meat, poultry, eggs and milk.

Many of the studies didn't specify their standards for what constituted "organic" food - which can cost as much as twice what conventional food costs - the researchers wrote Monday in the Annals of Internal Medicine.

According to United States Department of Agriculture standards, organic farms have to avoid the use of synthetic pesticides and fertilizers, hormones and antibiotics. Organic livestock must also have access to pastures during grazing season.

Many conventional farms in the U.S., in contrast, use pesticides to ward off bugs and raise animals in crowded indoor conditions with antibiotics in their feed to promote growth and ward off disease. The Food and Drug Administration has been examining that type of antibiotic use and its contribution to drug-resistant disease in humans.

SAME VITAMINS

Smith-Spangler and her colleagues found there was no difference in the amount of vitamins in plant or animal products produced organically and conventionally - and the only nutrient difference was slightly more phosphorus in the organic products.

Organic milk and chicken may also contain more omega-3 fatty acids, they found - but that was based on only a few studies.

There were more significant differences by growing practice in the amount of pesticides and antibiotic-resistant bacteria in food.

More than one-third of conventional produce had detectable pesticide residues, compared to seven percent of organic produce samples. And organic chicken and pork was 33 percent less likely to carry bacteria resistant to three or more antibiotics than conventionally-produced meat.

Smith-Spangler told Reuters Health it was uncommon for either organic or conventional foods to exceed the allowable limits for pesticides, so it's unclear whether a difference in residues would have an effect on health.

But Chensheng Lu, who studies environmental health and exposure at the Harvard School of Public Health in Boston, said that while the jury is still out on those effects, people should consider pesticide exposure in their grocery-shopping decisions.

"If I was a smart consumer, I would choose food that has no pesticides," Lu, who wasn't involved in the new study, told Reuters Health. "I think that's the best way to protect your health."

He said more research is necessary to fully explore the potential health and safety differences between organic and conventional foods, and that it's "premature" to conclude organic meat and produce isn't any healthier than non-organic versions.

"Right now I think it's all based on anecdotal evidence," Lu said.

UCLA researchers have discovered a type of cell that is the "missing link" between bone marrow stem cells and all the cells of the human immune system.

The finding may help explain how a healthy immune system is produced and how disease can lead to poor immune function.

The studies were done using human bone marrow, which contains all the stem cells that produce blood during postnatal life.

The research team was "intrigued to find this particular bone marrow cell because it opens up a lot of new possibilities in terms of understanding how human immunity is produced from stem cells throughout life," said study senior author Dr. Gay Crooks, co-director of the Eli and Edythe Broad Center of Regenerative Medicine and a co-director of the Cancer and Stem Cell Biology program at UCLA's Jonsson Comprehensive Cancer Center.

Understanding the process of normal blood formation in human adults is a crucial step in shedding light on what goes wrong during the process that results in leukemia, or cancer of the blood.

Before this study, researchers had a fairly good idea of how to find and study the blood stem cells of the bone marrow. The stem cells live forever, reproduce themselves and give rise to all the cells of the blood. In the process, the stem cells divide and produce intermediate stages of development called progenitors, which make various blood lineages like red blood cells or platelets.

Crooks was most interested in the creation of the progenitors that form the entire immune system, which consists of many different cells called lymphocytes, each with a specialized function to fight infection.

"Like the stem cells, the progenitor cells are also very rare, so before we can study them we needed to find the needle in the haystack." said Lisa Kohn, a member of the UCLA Medical Scientist Training Program and first author in the paper.

Previous work had found a fairly mature type of lymphocyte progenitor with a limited ability to differentiate, but the new work describes a more primitive type of progenitor primed to produce the entire immune system, Kohn said

Once the lymphoid primed progenitor had been identified, Crooks and her team studied how gene expression changed during the earliest stages of its production from stem cells.

"The gene expression data convinced us that we had found a unique stage of development in the immune system. There was a set of genes that the lymphoid-primed cell shares with the bone marrow stem cells and a unique gene expression of its own once it becomes active. This data provided us with an understanding of what genes are important in creating all the cells of the immune system," said Crooks, a professor of pathology and pediatrics.

"The information could allow us to manipulate bone marrow to help create a stronger immune system," he noted.

The study appeared in the early online edition of Nature Immunology.

Two studies by University of Alabama at Birmingham researchers have suggested that deep-brain stimulation (DBS) may stop uncontrollable shaking in patients with Parkinson's disease and essential tremor by imposing its own rhythm on the brain.

DBS uses an electrode implanted beneath the skin to deliver electrical pulses into the brain more than 100 times per second. Although this technology was approved by the Food and Drug Administration more than 15 years ago, it remains unclear how it reduces tremor and other symptoms of movement disorders.

With the help of electroencephalography or EEG - electrodes placed on the scalp - study authors used new techniques to suppress the electrical signal associated with the DBS electrode. That enabled the first clear, non-invasive EEG measurements of the underlying brain response during clinically effective, high-frequency brain stimulation in humans.

The results showed that nerves in the cerebral cortex, the outer layer of the brain, fire with rapid and precise timing in response to individual stimulus pulses. This suggests that DBS may synchronize the firing of nerve cells and break the abnormal rhythms associated with involuntary movements in Parkinson's disease and essential tremor.

The newly identified rhythm was captured during effective DBS treatment, so it could represent a new physiological measure of the stimulation dose, said the authors. If validated, such a yardstick could help to guide the fine-tuning of DBS stimulator settings in patients for more lasting relief, fewer side effects and less-frequent battery-replacement surgeries.

"Though it's clear that more work is needed to better understand these initial observations, we're very excited by our findings because they may provide a biological marker for improvement in the symptoms of these patients," said Harrison Walker, M.D., assistant professor in the UAB Department of Neurology's Division of Movement Disorders and lead author of the study.

In current clinical practice, stimulator settings are adjusted by trial and error, requiring careful observation of changes in symptoms over multiple clinic visits. But such immediate, visual feedback may not be available as DBS is applied to neurological or psychiatric conditions such as epilepsy, severe depression or obsessive compulsive disorder.

In these diseases, an effective dose measurement could be especially useful in optimizing DBS therapy.

In both studies, EEG data revealed that nerve cells in the cerebral cortex discharged about one one-thousandth of a second, or one millisecond, after each stimulus pulse was delivered into the brain.

The authors argue that this rapid response on the brain's surface most likely represented "backfiring" along extensions of cortical nerve cells called axons that connect them to deeper regions within the brain where the DBS electrodes were placed. Interestingly, this rapid response on the brain surface was present in both studies, regardless of the stimulation target or the disease state of the patient.

Although prior studies had hinted at these brain responses, they were unable to measure them directly because of interference from the competing electrical signal emitted by the DBS pulse itself. Walker and his team reversed the polarity of the stimulation pulse, in effect subtracting the DBS signal and leaving only the EEG signal associated with the brain activity.

The new technique also enabled the researchers to show that the size of the brain response at one millisecond after a DBS pulse is dependent on the intensity or voltage of the stimulus pulse, and that larger brain responses were closely associated with improvement in tremor.

"While early, this work has tremendous implications for the understanding of brain mechanisms responsible for a number of neurological and psychiatric diseases," said co-author Barton Guthrie, M.D., in the Division of Neurosurgery.

"Further studies are planned to confirm these measures and mechanisms and we believe this insight will soon make valuable contributions to the next generation of DBS treatments," he added.

The studies were published recently in the journal Movement Disorders.

Children whose mothers are in full-time employment are at greater risk of obesity even if their father is a stay-at-home parent, according to experts.

Their study highlights that men about the house fail to realise the importance of their child's eating habits.

Study authors say that it is important for both parents to discuss day-to-day responsibilities, including food preparation and mealtimes.

John Cawley, from Cornell University and Feng Liu used data on almost 25,000 families from a yearly survey of how Americans spend their time.

Data showed that on average women who worked spent 127 fewer minutes per day with their children than stay-at-home mothers.

However stay-at-home fathers failed to offset the difference "We're not trying to say men are scum," Cawley told BuzzFeed.

Cawley and Liu noted that preparing meals from scratch and eating as a family could decrease a child's risk of obesity.

They also suggest that schools could offer healthier food and better physical education.

The study is published in the June issue of Economics and Human Biology.

Telephone therapy may help people dependent on marijuana kick the habit, a new study from Australia suggests.

Researchers found that almost twice as many users significantly cut back on marijuana following four hour-long phone counseling sessions compared to those who were put on a treatment waiting list.

Knowing therapy may work over the phone could help extend treatment to people in remote areas where in-person therapy is hard to come by, according to Peter Gates, from the University of New South Wales, and his colleagues.

Phone therapy might also be the preferred option for some marijuana users who would rather be more anonymous when receiving counseling, they added.

"At least for these moderate cases, it seems like there's a subset of people who can benefit just as much from telephone therapy as they can from face-to-face therapy," said Alan Budney, a psychiatry professor who studies marijuana dependence at the Geisel School of Medicine at Dartmouth College in Lebanon, New Hampshire.

Budney said that, as with alcohol and other drugs, marijuana use starts becoming dependence when it causes problems in a person's work, school or home life, or they've tried to quit the habit but can't.

Gates and his colleagues wrote in the journal Addiction that there's already evidence to support in-person talk therapy for marijuana dependence.

To see if that success would extend to over-the-phone treatment, they randomly assigned 160 users who'd called a marijuana information and helpline to either get four weekly counseling sessions or to be put on a wait list for phone counseling.

During therapy sessions, counselors discussed marijuana users' readiness to change their behavior, encouraged them to cut back on pot smoking and ultimately advised them on how to cope with and avoid triggers to go back to using.

Three months later, 110 of the original participants had completed the study and were interviewed again by the researchers. Thirty-nine percent of those who went through the counseling had cut their pot use at least in half, compared to 20 percent of the no-counseling group.

Users went from smoking on 22 to 23 out of the last 28 days at the start of the study to seven out of 28 days after phone counseling.

People in the comparison group also cut back, but not to the same extent: they reported smoking 13 out of the prior 28 days, on average.

Because they only had smoking data three months out, the researchers couldn't tell whether phone therapy had long-term benefits, or whether people who got counseling eventually went back to their old using habits.

According to the National Institute on Drug Abuse, marijuana is the most commonly used illicit drug in the United States, with 17.4 million people reporting using it in the past month on a 2010 survey. NIDA also estimates that nine percent of people who start using marijuana will become dependent on the drug.

Budney has studied computer-based interventions for marijuana dependence, which he says could also be cheaper and more convenient than in-person therapy. But most patients can't get computer or phone therapy yet, he told Reuters Health.

"There's not a lot of that available right now - it's mostly in the testing phase."

Still, Budney said in the future computer and phone therapy "should be considered as a first-line of treatment" for marijuana dependence along with in-person talk therapy.