A high-fat diet enriched with cottonseed oil drastically improved cholesterol profiles in young adult men, say researchers at the University of Georgia. The researchers conducted a five-day outpatient feeding trial of 15 healthy, normal weight men to test the effects of diets enriched with cottonseed oil and olive oil on lipid profiles. Participants showed significant reductions in cholesterol and triglycerides in the cottonseed oil trial compared to minimal changes on the olive oil-enriched diet.
The results appear in the journal Nutrition Research. “One of the reasons these results were so surprising is because of the magnitude of change observed with the cottonseed oil diet,” says Jamie Cooper, an associate professor in the UGA College of Family and Consumer Sciences’ department of foods and nutrition and the corresponding author of the journal article. “To see this amount of change in such a short period of time is exciting.” The subjects, all healthy men between the ages of 18 and 45, were provided high-fat meals for five days in two separate, tightly controlled trials. The only difference was the use of either cottonseed oil or olive oil in the meals. Participants showed an average decrease of eight percent in total cholesterol on the cottonseed oil diet, along with a 15 percent decrease in low-density lipoprotein or LDL - the “bad” cholesterol - and a 30 percent decrease in triglycerides. This diet also increased high-density lipoproteins, or HDL - the “good” cholesterol - by eight percent.
Researchers suggested a fatty acid unique to cottonseed oil, dihydrosterculic acid, may help prevent the accumulation of triglycerides, a type of fat, in the body. “By doing that, it pushes the body to burn more of that fat because it can’t store it properly, so you have less lipid and cholesterol accumulation,” Cooper said. That mechanism, in addition to the high polyunsaturated fat and omega-6 content of cottonseed oil, seems to be a key component to the beneficial effects on lipid profiles. Researchers plan to expand the study to include older adults with high cholesterol as well as a longer feeding intervention.
Extra-Virgin Olive Oil Preserves Memory, Protects Brain Against Alzheimer's
The Mediterranean diet, rich in plant-based foods, is associated with a variety of health benefits, including a lower incidence of dementia. Researchers at the Lewis Katz School of Medicine at Temple University (LKSOM) have identified a specific ingredient that protects against cognitive decline: extra-virgin olive oil, a major component of the Mediterranean diet. In a study published in the Annals of Clinical and Translational Neurology, the researchers show that the consumption of extra-virgin olive oil protects memory and learning ability and reduces the formation of amyloid-beta plaques and neurofibrillary tangles in the brain – classic markers of Alzheimer's disease.
The team also identified the mechanisms underlying the protective effects of extra-virgin olive oil. “We found that olive oil reduces brain inflammation but most importantly activates a process known as autophagy,” says senior investigator Domenico Praticò, MD, Professor in the Departments of Pharmacology and Microbiology and the Center for Translational Medicine at LKSOM. Autophagy is the process by which cells break down and clear out intracellular debris and toxins, such as amyloid plaques and tau tangles. “Brain cells from mice-fed diets enriched with extra-virgin olive oil had higher levels of autophagy and reduced levels of amyloid plaques and phosphorylated tau,” Praticò said. The latter substance, phosphorylated tau, is responsible for neurofibrillary tangles, which are suspected of contributing to the nerve cell dysfunction in the brain that is responsible for Alzheimer's memory symptoms.
Previous studies have suggested that the widespread use of extra-virgin olive oil in the diets of people living in the Mediterranean areas is largely responsible for the many health benefits linked to the Mediterranean diet. “The thinking is that extra-virgin olive oil is better than fruits and vegetables alone, and as a monounsaturated vegetable fat it is healthier than saturated animal fats,” Praticò added. In order to investigate the relationship between extra-virgin olive oil and dementia, Dr. Praticò and colleagues used a well-established Alzheimer's disease mouse model. Known as a triple transgenic model, the animals develop three key characteristics of the disease: memory impairment, amyloid plagues, and neurofibrillary tangles.
Olive Oil-Enriched Diet
The researchers divided the animals into two groups, one that received a chow diet enriched with extra-virgin olive oil and one that received the regular chow diet without it. The olive oil was introduced into the diet when the mice were six months old, before symptoms of Alzheimer's disease begin to emerge in the animal model. In overall appearance, there was no difference between the two groups of animals. However, at age nine months and 12 months, mice on the extra virgin olive oil-enriched diet performed significantly better on tests designed to evaluate working memory, spatial memory, and learning abilities. Studies of brain tissue from both groups of mice revealed dramatic differences in nerve cell appearance and function. “One thing that stood out immediately was synaptic integrity,” Praticò said.
The integrity of the connections between neurons, known as synapses, were preserved in animals on the extra-virgin olive oil diet. In addition, compared to mice on a regular diet, brain cells from animals in the olive oil group showed a dramatic increase in nerve cell autophagy activation, which was ultimately responsible for the reduction in levels of amyloid plaques and phosphorylated tau. “This is an exciting finding for us,” explained Praticò. “Thanks to the autophagy activation, memory and synaptic integrity were preserved, and the pathological effects in animals otherwise destined to develop Alzheimer's disease were significantly reduced. This is a very important discovery, since we suspect that a reduction in autophagy marks the beginning of Alzheimer's disease.”
Praticò and colleagues plan next to investigate the effects of introducing extra-virgin olive oil into the diet of the same mice at 12 months of age, when they have already developed plaques and tangles. “Usually when a patient sees a doctor for suspected symptoms of dementia, the disease is already present,” Praticò added. “We want to know whether olive oil added at a later time point in the diet can stop or reverse the disease.”
Essential Oils From Garlic Kill Lyme Disease Bacteria
Oils from garlic and several other common herbs and medicinal plants show strong activity against the bacterium that causes Lyme disease, according to a study by researchers at Johns Hopkins Bloomberg School of Public Health. These oils may be especially useful in alleviating Lyme symptoms that persist despite standard antibiotic treatment.
The study, published in the journal Antibiotics, included lab-dish tests of 35 essential oils - oils that are pressed from plants or their fruits and contain the plant’s main fragrance or “essence.” The Bloomberg School researchers found that 10 of these, including oils from garlic cloves, myrrh trees, thyme leaves, cinnamon bark, allspice berries and cumin seeds, showed strong killing activity against dormant and slow-growing “persister” forms of the Lyme disease bacterium. “We found that these essential oils were even better at killing the ‘persister’ forms of Lyme bacteria than standard Lyme antibiotics,” says study senior author Ying Zhang, MD, Ph.D., professor in the Department of Molecular Microbiology and Immunology at the Bloomberg School.
There are an estimated 300,000 new cases of Lyme disease each year in the United States. Standard treatment with doxycycline or an alternative antibiotic for a few weeks usually clears the infection and resolves symptoms. However, about 10 to 20 percent of patients report persistent symptoms including fatigue and joint pain often termed “persistent Lyme infection” or “post-treatment Lyme disease syndrome” (PTLDS) that in some cases can last for months or years. The cause of this lingering syndrome isn’t known, but it is known that cultures of Lyme disease bacteria, Borrelia burgdorferi, can enter a so-called stationary phase in which many of the cells divide slowly or not at all. The slow-dividing or dormant cells are “persister” cells, which can form naturally under nutrient starvation or stress conditions, and are more resistant to antibiotics. Some researchers have sought other drugs or medicinal compounds that can kill persister Lyme bacteria in the hope that these compounds can be used to treat people with persistent Lyme symptoms.
In a 2017, study Zhang and his lab team found that essential oils from oregano, cinnamon bark, clove buds, citronella and wintergreen killed stationary phase Lyme bacteria even more potently than daptomycin, the champion among tested pharmaceuticals. In the new study Zhang and his team extended their lab-dish testing to include 35 other essential oils, and found 10 that show significant killing activity against stationary phase Lyme bacteria cultures at concentrations of just one part per thousand. At this concentration, five of these oils, derived respectively from garlic bulbs, allspice berries, myrrh trees, and spiked ginger lily blossoms may change fruit. They successfully killed all stationary phase Lyme bacteria in their culture dishes in seven days, so no bacteria grew back in 21 days. Oils from thyme leaves, cumin seeds and amyris wood also performed well, as did cinnamaldehyde, the fragrant main ingredient of cinnamon bark oil.
Lab-dish tests such as these represent an early stage of research, but Zhang and colleagues hope in the near future to continue their investigations of essential oils with tests in live animals, including tests in mouse models of persistent Lyme infection. If those tests go well and the effective doses seem safe, Zhang expects to organize initial tests in humans. “At this stage these essential oils look very promising as candidate treatments for persistent Lyme infection, but ultimately we need properly designed clinical trials,” Zhang said.
Essential Oils Can Assist With Livestock Digestion
Kansas State University researchers found that essential oils can play a role in livestock health. Essential oils are removed from plants and distilled into concentrated forms that distributors say support immunity and other functions of the body. In a study, professors Evan Titgemeyer, professor and graduate program director in the animal sciences and industry department in the College of Agriculture, and T.G. Nagaraja, professor of microbiology in the university's College of Veterinary Medicine, found that limonene, which is in lemon oil, and thymol, which is in thyme oil, help combat a harmful bacterium in cattle stomachs. The bacterium, Fusobacterium necrophorum, makes dietary protein less available to the animal. The results were published in the Journal of Dairy Science and the Journal of Animal Science.
The Food and Drug Administration has issued guidance to minimize the use of some antibiotics in livestock. The FDA's guidance aims to avoid exposing people's food to antibiotic-resistant bacteria, Nagaraja says. As the researchers started studying alternative treatments to antibiotic use, one of their team members, Eman Elkaweel, who was then a graduate student in animal science, suggested a substance that was new to the professors. "She wanted to test some products that might have the potential to be used in her home country of Egypt, so we contacted a company that sold products containing essential oil components," added Titgemeyer.
Nagaraja and Titgemeyer tested five essential oil components: eugenol, guaiacol, limonene, thymol and vanillin. They wanted to determine the compounds' ability to inhibit growth of Fusobacterium necrophorum. Limonene and thymol performed best. Follow-up testing between the two showed that limonene was slightly more effective than thymol and nearly as effective as tylosin, a commonly used antibiotic and feed additive used to hinder bacterial growth and the incidence of liver abscesses in cattle. "While livestock producers often turn to antibiotics, our study shows that some essential oils also can inhibit microbial growth," Titgemeyer said. "Certain essential oil compounds can target specific bacterial populations and optimize animal health."
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