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Author: Sima

Published on Leave a comment on Loneliness Is a Health Risk

Loneliness or social isolation is a health risk that can increase the risk of chronic illness and premature death. Why?  Loneliness leads to fight-or-flight stress signaling, which can ultimately affect the production of white blood cells. Essentially, lonely people had a less effective immune response and more inflammation than non-lonely people. The study was part of the Chicago Health, Aging, and Social Relations Study (CHASRS) and followed 144 people over 10 years. From Science Daily:

Loneliness triggers cellular changes that can cause illness, study shows

Loneliness is more than a feeling: For older adults, perceived social isolation is a major health risk that can increase the risk of premature death by 14 percent.

Now a team of researchers, including U Chicago psychologist and leading loneliness expert John Cacioppo, has released a study shedding new light on how loneliness triggers physiological responses that can ultimately make us sick. The paper.... shows that loneliness leads to fight-or-flight stress signaling, which can ultimately affect the production of white blood cells. The study examined loneliness in both humans and rhesus macaques, a highly social primate species.

Previous research from this group had identified a link between loneliness and a phenomenon they called "conserved transcriptional response to adversity" or CTRA. This response is characterized by an increased expression of genes involved in inflammation and a decreased expression of genes involved in antiviral responses. Essentially, lonely people had a less effective immune response and more inflammation than non-lonely people.

For the current study, the team examined gene expression in leukocytes, cells of the immune system that are involved in protecting the body against bacteria and viruses. As expected, the leukocytes of lonely humans and macaques showed the effects of CTRA--an increased expression of genes involved in inflammation and a decreased expression of genes involved in antiviral responses. But the study also revealed several important new pieces of information about loneliness' effect on the body.

Next, the team investigated the cellular processes linking social experience to CTRA gene expression in rhesus macaque monkeys at the California National Primate Research Center, which had been behaviorally classified as high in perceived social isolation. Like the lonely humans, the "lonely like" monkeys showed higher CTRA activity. They also showed higher levels of the fight-or-flight neurotransmitter, norepinephrine.

Previous research has found that norepinephrine can stimulate blood stem cells in bone marrow to make more of a particular kind of immune cell--an immature monocyte that shows high levels of inflammatory gene expression and low levels of antiviral gene expression. Both lonely humans and "lonely like" monkeys showed higher levels of monocytes in their blood.

Taken together, these findings support a mechanistic model in which loneliness results in fight-or-flight stress signaling, which increases the production of immature monocytes, leading to up-regulation of inflammatory genes and impaired anti-viral responses. The "danger signals" activated in the brain by loneliness ultimately affect the production of white blood cells. The resulting shift in monocyte output may both propagate loneliness and contribute to its associated health risks.

Published on Leave a comment on Brains of Teen Football Players Don’t Fully Heal During the Off Season

This past week there was discussion of the number of high school football players that die annually while playing football (at least 5). But the bigger risk - because it involves so many players - is the damage to brains that occurs from concussions and from just being hit in football. The response from football enthusiasts is that there are safeguards now - that football players don't play after a concussion until they "heal" (show no obvious symptoms). But do they really heal? And much of the damage is from repeated hits, without having a concussion (sub-concussive blows or hits), what about the damage from that?

This study found that repeated head hits in football can cause changes in brain chemistry and metabolism, even in high school players not diagnosed with concussions. And even after the lengthy off-season (somewhere between two and five months after the season has ended)—the majority of players are still showing that they had not fully recovered. The researchers also made it clear that 2 weeks is not enough time to heal from a concussion. Scary long-term implications - what is happening to brains that never truly heal from past seasons as the players start playing in the next season? From Futurity:

High School Football: Teen Brains Don't Heal During Offseason

Brain scans of high school football players taken before, during, and after the season raise concerns they don’t fully recover from repeated head hits. The researchers used an imaging technique called proton magnetic resonance spectroscopy (1H MRS) to study the brains of 25 high school football players and compared them to the brains of teenagers involved in non-contact sports. The findings suggest repeated head hits in football can cause changes in brain chemistry and metabolism, even in players not diagnosed with concussions. 

“We are seeing damage not just to neurons, but also to the vasculature and glial cells in the brain,” says Eric Nauman, professor of mechanical engineering, basic medical sciences, and biomedical engineering at Purdue University. “I was particularly disturbed that when you get to the offseason—we are looking somewhere between two and five months after the season has ended—the majority of players are still showing that they had not fully recovered.”

The 1H MRS data provide details about the blood flow, metabolism, and chemistry of neurons and glial cells important for brain function. The data also revealed a “hypermetabolic response” during the preseason, as though the brain was trying to heal connections impaired from the previous season. “We found that in the preseason for the football players in our study, one part of the brain would be associating with about 100 other regions, which is much higher than the controls,” says Thomas Talavage,  professor of electrical and computer engineering and biomedical engineering and co-director of the Purdue MRI Facility.

“The brain is pretty amazing at covering up a lot of changes. Some of these kids have no outward symptoms, but we can see their brains have rewired themselves to skip around the parts that are affected.”

One of the research papers shows that knowing a player’s history of specific types of hits to the head makes it possible to accurately predict “deviant brain metabolism,” suggesting that sub-concussive blows can produce biochemical changes and potentially lead to neurological problems, which indicates a correlation between players taking the heaviest hits and brain chemistry changes.

The data shows that the neurons in the motor cortex region in the brains of football players produced about 50 percent less of the neurotransmitter glutamine compared to controls. “We are finding that the more hits you take, the more you change your brain chemistry, the more you change your brain’s ability to move blood to the right locations,” Nauman says.

“Recent proton magnetic resonance spectroscopy studies argue that the recommended two-week window of rest is insufficient for full metabolic recovery after concussion,” Nauman says. “Those returning to play prior to full recovery could incur a second concussion with symptoms and metabolic changes more lasting than the first.”

Published on Leave a comment on How a Sneeze Travels Through a Room

 Cold and flu season will soon be here, so it's time to review sneeze basics. Here's a nice little study looking at where our sneeze germs wind up - answer: basically all over the room within a "high propulsion sneeze cloud". From Medical Xpress;

Ah-choo! Sneeze 'cloud' quickly covers a room, study finds

Just in time for cold and flu season, a new study finds the average human sneeze expels a high-velocity cloud that can contaminate a room in minutes. Researchers at the Massachusetts Institute of Technology (MIT) came to that conclusion by analyzing videos of two healthy people sneezing about 50 times over several days.

It's well known that sneezes can spread infectious diseases such as measles or the flu, because viruses suspended in sneeze droplets can be inhaled by others or deposited on surfaces and later picked up as people touch them. But it wasn't clear how far sneeze droplets can spread, or why some people are more likely to spread illness through sneezes than others. In a prior study, the team led by MIT's Lydia Bourouiba found that within a few minutes, sneeze droplets can cover an area the size of a room and reach ventilation ducts at ceiling height.

In their latest new study, they discovered how sneeze droplets are formed within what they called a "high-propulsion sneeze cloud." The findings are slated for presentation Monday at the annual meeting of the American Physical Society in Mobile, Ala.

"Droplets are not all already formed and neatly distributed in size at the exit of the mouth, as previously assumed in the literature," Bourouiba said in a society news release. Rather, sneeze droplets "undergo a complex cascading breakup that continues after they leave the lungs, pass over the lips and churn through the air," said Bourouiba, who is head of MIT's Fluid Dynamics of Disease Transmission Laboratory.

Published on Leave a comment on Breast Milk and Preserving Sight In Preemies

Another excellent reason to breastfeed premature infants - to increase the odds of preventing retinopathy of prematurity (ROP), which is the reason preemies can go blind. It occurs when blood vessels in the retinas of premature infants start to grow out of control. If the abnormal growth continues, the retinas detach, and this can cause blindness.

Sadly, an ROP epidemic occurred in the 1940s and early 1950s when hospital nurseries began using excessively high levels of oxygen in incubators to save the lives of premature infants. During this time, ROP was the leading cause of blindness in children in the US. In 1954, scientists funded by the National Institutes of Health determined that the relatively high levels of oxygen routinely given to premature infants at that time were an important risk factor, and that reducing the level of oxygen given to premature babies reduced the incidence of ROP.

Nowadays ROP is a leading cause of childhood blindness in developed countries. A large US study found that in extremely preterm infants with a gestational age of 22 to 28 weeks, the incidence of ROP was 59% (96% at 22 weeks and 32% at 28 weeks). ROP is considered a  multifactorial disease, and risk factors such as prematurity, low birth weight, oxygen therapy, and oxidative stress have been associated with its development.

This recent study was a meta-analysis of five studies (of 2208 pre-term infants), and it found that the overall incidence of ROP was reduced among infants fed human breast milk compared with those fed formula. The best results in preventing severe ROP was in babies fed exclusively breast milk (up to 90% reduction) or mainly human breast milk feeding. It is thought that breast milk may protect against the development of ROP because of its antioxidant and immune-protective properties.  Note that studies involving donor milk were not included because past studies did not find any advantage for donor milk over formula. This may be possibly related to loss of the breast milk microbes (breast milk normally contains up to 700 species of bacteria) during processing (pasteurizing/heat treatment of milk for 30 minutes) and storage of donor milk. From NPR:

Mother's Milk May Help Prevent Blindness In Preemies

If Stevie Wonder had been born three decades later, we might never have gotten "Superstition" and "Isn't She Lovely" — but the musician might never have gone blind, either. Born premature, Wonder developed retinopathy of prematurity, an eye disease that afflicts more than half of babies born before 30 weeks of gestation.Though treatments were developed in the 1980s, about 400 to 600 U.S. children and 50,000 children worldwide still go blind every year from the condition. Now a study suggests that number could be slashed by more than half if all those preemies received their mothers' milk.

The study, actually a combined analysis of five studies from 2001 through 2013, found that preemies receiving human milk from their mothers had 46 to 90 percent lower odds of retinopathy of prematurity (ROP), depending on how much milk they received and how severe the ROP was. The studies were observational, so they cannot show that breast milk directly caused the lower risk.

Of the infants who develop ROP, most recover and develop well without treatment, but about 10 percent develop severe ROP, increasing their risk of blindness, Chiang said. About half of those infants need treatment, which will prevent blindness in 80 to 90 percent of them.

The new research analyzed the outcomes of 2,208 preterm infants based on whether they received exclusive human milk, any human milk, mainly human milk (more than 50 percent), exclusive formula, any formula or mainly formula. The study did not include donor milk, so all the milk was the mother's pumped or hand-expressed breast milk.

Infants who exclusively received breast milk had 89 percent reduced odds of severe ROP compared to infants who received any formula. Infants who received a mixture of breast milk and formula had roughly half the odds of developing severe ROP compared to infants exclusively receiving formula. The analysis included a very large older study that had found no reduced risk for ROP from breast milk, but most infants in that study received less than 20 percent breast milk.

Until the 1940s and 1950s, ROP did not exist because infants born prematurely rarely survived, Chiang said. As doctors learned to how to keep these tiny babies, usually little more than 3 pounds at birth, alive, they discovered that the blood vessels in their retinas would often start to grow out of control. If the abnormal growth continued, their retinas detached, causing blindness.

The cause of ROP isn't entirely understood, but scientists believe oxidative stress can stimulate the abnormal growth of the blood vessels. Providing preemies with oxygen is often key to their survival, but that oxygen exposure might lead to ROP, according to Jianguo Zhou, a neonatologist in Shanghai, and lead author of the study.

Published on Leave a comment on Some Health Benefits of Eating Tree Nuts Daily

A newly published study reviewed 61 studies that looked at daily tree nut consumption on cardiovascular risk factors and found many health benefits. Tree nut (walnuts, almonds, pistachios, macadamia nuts, pecans, cashews, hazelnuts, and Brazil nuts) consumption lowers total cholesterol, LDL cholesterol, triglycerides, and ApoB, the primary protein in LDL cholesterol. It appeared that nut dose is more important than nut type in lowering cholesterol. The beneficial health effects are greater at about 60 grams (about 2 oz or 2 servings) or more nuts consumed per day, but positive health effects are also found at one serving per day. Five studies found that 100 g nuts per day lowered concentrations of LDL cholesterol by up to 35 mg/dL - an effect size comparable to some statin regimens.

Tree nuts are rich in unsaturated fats, soluble fiber, antioxidants, and phytosterols, which produce beneficial effects on serum lipids, blood pressure, and inflammation. Most studies have looked at walnut and almond consumption, but studies found positive benefits for all types of nuts consumed. From Medical Xpress:

Study finds tree nut consumption may lower risk of cardiovascular disease

A new study published in the American Journal of Clinical Nutrition found that consuming tree nuts, such as walnuts, may lower the risk of cardiovascular disease. After conducting a systematic review and meta-analysis of 61 controlled trials, one of the authors, Michael Falk, PhD, Life Sciences Research Organization, found that consuming tree nuts lowers total cholesterol, triglycerides, LDL cholesterol, and ApoB, the primary protein found in LDL cholesterol. These are key factors that are used to evaluate a person's risk of cardiovascular disease. Walnuts were investigated in 21 of the 61 trials, more than any other nut reviewed in this study.

"Our study results further support the growing body of research that tree nuts, such as walnuts, can reduce the risk of cardiovascular diseases," said Dr. Falk. "Tree nuts contain important nutrients such as unsaturated fats, protein, vitamins and minerals. Walnuts are the only nut that provide a significant amount (2.5 grams per one ounce serving) of alpha-linolenic acid (ALA), the plant-based form of omega-3s."

Beyond finding that tree nuts lower total cholesterol, triglycerides, LDL cholesterol and ApoB, researchers also found that consuming at least two servings (two ounces) per day of tree nuts, such as walnuts, has stronger effects on total cholesterol and LDL. Additionally, results showed that tree nut consumption may be particularly important for lowering the risk of heart disease in individuals with type 2 diabetes.

Of 1,301 articles surveyed, 61 trials met eligibility criteria for this systematic review and meta-analysis, totaling 2,582 unique participants. Trials directly provided nuts to the intervention group rather than relying solely on dietary advice to consume nuts. The dose of nuts varied from 5 to 100 g/day and most participants followed their typical diet.

Published on Leave a comment on Lifestyle Habits That May Protect Men From Lethal Prostate Cancer

Data from 2 huge studies was analyzed and found that vigorous exercise and other healthy habits seems to cut the chance of developing aggressive and lethal prostate cancer up to 68 percent in men over 60. The beneficial lifestyle habits are: weekly vigorous exercise or activity to the point of sweating, at least 7 servings of tomatoes a week, at least one serving of fatty fish per week, reduced intake of processed meat, and being a long-term non-smoker.

Interestingly, vigorous activity or exercise to sweating - ideally up to 3 hours a week - showed the biggest association with a 34 % reduced risk of aggressive prostate cancer.

From Science Daily: Working up a sweat may protect men from lethal prostate cancer

A study that tracked tens of thousands of midlife and older men for more than 20 years has found that vigorous exercise and other healthy lifestyle habits may cut their chances of developing a lethal type of prostate cancer by up to 68 percent.

While most prostate cancers are "clinically indolent," meaning they do not metastasize and are nonlife-threatening, a minority of patients are diagnosed with aggressive disease that invades the bone and other organs, and is ultimately fatal. Lead author Stacey Kenfield, ScD, of UCSF, and a team of researchers at UCSF and Harvard, focused on this variant of prostate cancer to determine if exercise, diet and smoke-free status might have life-saving benefits.

In the study, published in the Journal of the National Cancer Institute, the researchers analyzed data from two U.S. studies: the Health Professionals Follow-Up Study that tracked more than 42,000 males ages 40 to 75, from 1986 to 2010; and a second, the Physicians' Health Study that followed more than 20,000 males ages 40 to 84, from 1982 to 2010.

To gage the effects of lifestyle habits, the researchers developed a score based on the results of the health professionals survey, then applied it to the physicians' study. They assigned one point for each affirmative response to questions about regular intense exercise that induced sweating, body mass index (BMI) under 30, tobacco-free status for a minimum of 10 years, high intake of fatty fish, high intake of tomatoes and low intake of processed meat.

The researchers identified 576 cases of lethal prostate cancer in the health professionals' group and 337 cases in the physicians' group. Participants with 5 to 6 points in the health professionals' group had a 68 percent decreased risk of lethal prostate cancer and a 38 percent decreased risk was observed in the physicians' group for the same comparison.

"We estimated that 47 percent of lethal prostate cancer cases would be prevented in the United States if men over 60 had five or more of these healthy habits," said Kenfield, assistant professor in the Department of Urology at UCSF Medical Center, and formerly of the Department of Medicine at Harvard Medical School in Boston, where the study was initiated.

"It's interesting that vigorous activity had the highest potential impact on prevention of lethal prostate cancer. We calculated the population-attributable risk for American men over 60 and estimated that 34 percent of lethal prostate cancer would be reduced if all men exercised to the point of sweating for at least three hours a week," Kenfield said.

The researchers also calculated that lethal prostate cancer among American men over 60 would be cut by 15 percent if they consumed at least seven servings of tomatoes per week and that 17 percent would be spared this diagnosis if they consumed at least one serving of fatty fish per week. Reducing intake of processed meats would cut the risk by 12 percent, they reported. In contrast, the population-attributed risk for smoking was 3 percent, largely because the majority of older American men are long-term nonsmokers.

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Published on 1 Comment on Problems With Scented Candles

 Several people have recently asked me whether scented candles have any health effects. The answer is a big YES - they have many negative health effects, and so do other scented products such as air fresheners and dryer sheets (e,g, Bounce). All of them contain fragrances and other chemicals - all from petrochemicals (which means they are chemical products derived from petroleum). And yes - all 3 products are totally unnecessary, so ditch them for better health. View all of them as sources of indoor air pollution.

Most of the candles on the market are made with paraffin wax, derived from petroleum, and scented with synthetic fragrances, also derived from petroleum. Synthetic fragrances typically also contain phthalates that can interfere with your hormone system (endocrine disruptors).

In one study scientists at the South Carolina State University lit several brands of candles made of paraffin – the most common and inexpensive candle wax – as well as soy candles (thus vegetable based) and burned them for 5 to 6 hours in a chamber. All of the candles were unscented and undyed. They found that the paraffin candle smoke emits varying levels of pollutants, including benzene, toluene and ketones, as well as hydrocarbon chemicals called alkanes and alkenes, which are components of gasoline. They have been linked to cancer, asthma and birth defects. None of the vegetable-based soy candles produced toxic chemicals. From SC State University:  Frequent use of certain candles produces unwanted chemicals

Researchers point out that the emissions from burning an occasional paraffin candle will not likely cause health problems - it's the frequent lighting of scented paraffin candles in indoor rooms, and inhaling the pollutants in the air that may cause health problems, or as Dr. Massoudi of S. Carolina State University stated: "could contribute to the development of health risks like cancer, common allergies and even asthma."

Scented candles are known to release various volatile organic compounds (VOCs) including both pleasant aromas and toxic components both before lighting (unlit) and when lit. When lit, the "highest emission concentration" was of formaldehyde. Characterization of hazardous and odorous volatiles emitted from scented candles before lighting and when lit

By simply touching the candles, one absorbs chemicals through the skin.  Skin contact transfer of three fragrance residues from candles to human hands.

Safe candle alternatives are beeswax candles and unscented soy candles. These do not emit toxic chemicals when burned. However, all burning candles emit soot, which is ultrafine, lung-damaging particulate matter that's capable of penetrating deep into the lungs.

From Huffington Post: The Big Problem With Scented Candles

Scented candles are one of the easiest and most effective ways to mask unpleasant odors in your home....But one of the main problems with scented candles is the scent itself. According to Anne Steinemann, an environmental pollutants expert who is a professor of civil engineering and the chair of sustainable cities at the University of Melbourne, certain candles may emit numerous types of potentially hazardous chemicals, such as benzene and toluene. They can cause damage to the brain, lung and central nervous system, as well as cause developmental difficulties.

"I have heard from numerous people who have asthma that they can’t even go into a store if the store sells scented candles, even if they aren’t being burned," Steinemann added. "They emit so much fragrance that they can trigger asthma attacks and even migraines."

Researchers at South Carolina State University tested both petroleum-based paraffin wax candles and vegetable-based candles that were non-scented, non-pigmented and free of dyes. Their 2009 report concluded that while the vegetable-based candles didn't produce any potentially harmful pollutants, the paraffin candles "released unwanted chemicals into the air," said chemistry professor Ruhullah Massoudi in a statement.

It may be shocking to think that your favorite candles could potentially be bad for you, and made worse by added fragrances. Steinemann said for some people, the effects are "immediate, acute and severe," while others may not realize they are being effected until they gradually develop health issues.

Though the risk to you may be small, there are alternatives. Steinemann suggests going the unscented route, avoiding "even those with essential oils, as they can potentially have hazardous chemicals," she said. "It's almost like air fresheners with the fragrance just sitting there ... permeating surfaces in the room."

Published on Leave a comment on Drink Coffee and Live Longer?

 Drink coffee daily -  3 to 5 cups of either regular or decaffeinated - and live longer by lowering your risk of premature death from cardiovascular disease, neurological disease, type 2 diabetes, and suicide. Yes, it was an observational study, but the results are similar to what other studies are finding. From Medical Xpress:

Moderate coffee drinking may lower risk of premature death

People who drink about three to five cups of coffee a day may be less likely to die prematurely from some illnesses than those who don't drink or drink less coffee, according to a new study by Harvard T.H. Chan School of Public Health researchers and colleagues. Drinkers of both caffeinated and decaffeinated coffee saw benefits, including a lower risk of death from cardiovascular disease, neurological diseases, type 2 diabetes, and suicide.

"Bioactive compounds in coffee reduce insulin resistance and systematic inflammation," said first author Ming Ding, a doctoral student in the Department of Nutrition. "That could explain some of our findings. However, more studies are needed to investigate the biological mechanisms producing these effects."

Researchers analyzed health data gathered from participants in three large ongoing studies: 74,890 women in the Nurses' Health Study; 93,054 women in the Nurses' Health Study 2; and 40,557 men in the Health Professionals Follow-up Study. Coffee drinking was assessed using validated food questionnaires every four years over about 30 years. During the study period, 19,524 women and 12,432 men died from a range of causes.

In the whole study population, moderate coffee consumption was associated with reduced risk of death from cardiovascular disease, diabetes, neurological diseases such as Parkinson's disease, and suicide. Coffee consumption was not associated with cancer deaths. The analyses took into consideration potential confounding factors such as smoking, body mass index, physical activity, alcohol consumption, and other dietary factors.

Published on Leave a comment on American Academy of Pediatrics: End Routine Antibiotic Use in Animals

The American Academy of Pediatrics released a new report that the overuse of antibiotics in animals poses a real health risk to children. Giving routine antibiotics to animals leads to antibiotic resistant bacteria  - which means that antibiotics may not work when given to people. Most of the antibiotics sold in the U.S. each year - 80 percent- are used in animals that people than eat. The great majority of antibiotics given to animals are the same ones given to humans.The main way to ensure that the meat that you are purchasing is antibiotic-free is to buy meat labeled organic. And to buy organic dairy products (milk, butter, cheese, cream). Note that the reason routine use of antibiotics in animals has not been stopped so far in the USA is due to agriculture industry lobbying. From Medical Xpress:

Pediatricians' group urges cuts in antibiotic use in livestock

Overuse of antibiotics in farm animals poses a real health risk to children, the American Academy of Pediatrics warns in a new report.This common practice is already contributing to bacterial resistance to medicines and affecting doctors' ability to treat life-threatening infections in kids, according to the paper published online Nov. 16 in the journal Pediatrics.

"The connection between production uses of antibiotics in the agricultural sector to antibiotic resistance is alarming," said Victoria Richards, an associate professor of medical sciences at the Quinnipiac University School of Medicine in Hamden, Conn. She believes the danger is "not only for infants and children but other vulnerable populations, such as the pregnant and the older individuals."

As the academy explained in its warning, antibiotics are often added to the feed of healthy livestock to boost growth, increase feed efficiency or prevent disease. However, the practice can also make antibiotics ineffective when they are needed to treat infections in people. Some examples of emerging antibiotic germs include methicillin-resistant staphylococcus aureus (MRSA), C.difficile, and highly resistant strains of the tuberculosis bacterium. Each year, more than 2 million Americans develop antibiotic-resistant infections and more than 23,000 die from these infections, the academy said. And in 2013, the highest incidence of such infections was among children younger than 5, federal government statistics show. 

"Children can be exposed to multiple-drug resistant bacteria, which are extremely difficult to treat if they cause an infection, through contact with animals given antibiotics and through consuming the meat of those animals," report author Dr. Jerome Paulson, immediate past chair of the academy's executive committee of the Council on Environmental Health, said in an academy news release."Like humans, farm animals should receive appropriate antibiotics for bacterial infections," he said. "However, the indiscriminate use of antibiotics without a prescription or the input of a veterinarian puts the health of children at risk."

Spaeth noted that the U.S. Centers for Disease Control and Prevention, as well as the World Health Organization, have both called for a curbing of antibiotic use in animals. But the authors of the new report expressed concern over resistance from the agriculture and farming industry to such measures.

Published on Leave a comment on Which Mosquito Repellents Work?

People spend a lot of effort trying to repel mosquitos  - because the bites are so annoying and because they spread serious diseases. New research looking at different mosquito repellents - both DEET and non-Deet ("natural") products - had interesting results. What was once thought effective in repelling mosquitoes doesn't work at all (vitamin B patch), and what was thought attractive to mosquitoes may actually repel them (floral scents), and the "natural" alternatives may or may not work. Also - the species of mosquito is important (they tested Aedes aegypti and Aedes albopictus), for they found that there was some variation among the 2 species in what they were attracted to or repelled by. Best choices for protection lasting at least 2 hours: DEET repellants, Cutter lemon eucalyptus insect repellent, and Victoria's Secret Bombshell. Best protection lasting 4 hours: DEET repellants, and Cutter lemon eucalyptus insect repellent. This last non-DEET product contained lemon-eucalyptus oil containing p-menthane-3,8-diol. Of course there was an untreated control (an attractive to mosquitoes volunteer's bare hand) in the study for comparison purposes.

However, while EcoSmart organic insect repellent  worked for 4 hours for Ae. albopictus mosquitoes, it only worked for the first few minutes for Ae. aegypti mosquitoes (so don't buy this product). For years people thought that Avon Skin So Soft worked well as a repellent - well, forget it- not good at all. Other products that did not work: a mosquito skin patch (vitamin B), and Cutter natural insect repellent. These results showed that DEET-free products containing citronella or geraniol did not work. See the original study for the result lists for 10 products for both species of mosquitoes. From Popular Science:

VICTORIA’S SECRET PERFUME WARDS OFF MOSQUITOES, STUDY FINDS

Because mosquitoes carry diseases like malaria and dengue fever, and irritate us, humans do a lot to avoid them. In most places people have to fend for themselves against the pests by sleeping under mosquito nets or using repellant. A number of new repellant formulas have hit the market in recent years, many with questionable efficacy. Researchers at New Mexico State University decided to compare the effectiveness of different repellants and perfumes, according to a study published recently in the Journal of Insect Science.

The Y-shaped tube used in the study.  Rodriguez et al, Journal of Insect Science, 2015

The researchers tested eight commercially available repellents, two fragrances, and a vitamin B patch that reportedly keeps the mosquitoes at bay, on two different species of disease-carrying mosquitoes. To test the efficacy of each, the researchers put a mosquito at the long end of a Y-shaped plastic tube. One of the researchers who is particularly attractive to mosquitoes placed her two hands at the ends of both forked tubes—one hand was untreated, the other treated with the chemical being tested. If the mosquito avoided the tube with the treated hand by staying still or moving towards the untreated hand, the researchers determined that the repellent worked.

The researchers found that, among repellents, those that contained the tried-and-true ingredient DEET were most effective in warding off the mosquitoes. A few others, such as Cutter Lemon Eucalyptus Insect Repellent, worked almost as well, while most of them (including the vitamin patch) didn’t make any difference.

While those findings weren’t unexpected, the researchers were surprised to find that Avon Skin So Soft Bath Oil repelled the mosquitoes for about two hours. Another fragrance, Victoria’s Secret Bombshell perfume, also repelled the mosquitoes and lasted even longer.

That overturned the previous understanding about how mosquitoes interpret scents. “There was some previous literature that said fruity, floral scents attracted mosquitoes, and to not wear those,” said Stacy Rodriguez, a research assistant involved in the study, said in a statement. “It was interesting to see that the mosquitoes weren’t actually attracted to the person that was wearing the Victoria’s Secret perfume – they were repelled by it.”