Thursday, February 16, 2017

Carbs during workouts help immune system recovery


Dr Jonathan Peake and Dr Oliver Neubauer, from QUT's Institute of Health and Biomedical Innovation, led a research review of studies about exercise and immunity.

They found the best way to avoid unfavourable changes in the immune system during a post-workout recovery was consuming carbs during or immediately after the exercise.

The paper was published in the Journal of Applied Physiology.

"There is intense interest in what athletes can do to recover faster from exercise," Dr Peake said.

"Among various nutritional strategies to counteract immune depression during exercise recovery, carbohydrates have proven the most effective. Ingesting carbohydrates during vigorous exercise may help, because carbohydrates maintain blood sugar levels.

"Having stable blood sugar levels reduces the body's stress response, which in turn, moderates any undesirable mobilisation of immune cells. However, more research is warranted to verify that this also helps to prevent infections and illnesses."

Dr Peake said exercise can increase and decrease the number of immune cells in blood.

But he said studies did not support the long-held belief that exercising regularly without allowing sufficient time for the immune system to return to normal increased the risk of a weakened immune system.

"People often have fewer natural killer white blood cells after a workout but we now believe they move to other parts of the body, rather than being destroyed.

"Exercise is a form of stress and more vigorous exercise creates more physiological stress which causes physiological and biochemical changes in the body. To tackle the potential threats these changes highlight, the immune cells may simply move out of the blood stream to the lungs, for example.

"This still leaves our bodies vulnerable to infections and, generally speaking, the more strenuous the exercise, the longer it takes for the immune system to return to normal.

"Epidemiological evidence suggests that regular moderate exercise protects against upper respiratory illnesses, like the common cold, whereas regular intense exercise increases the risk of upper respiratory illnesses."

Dr Neubauer said the research suggested most people only need carbohydrates during high-intensity or prolonged exercise of 90 minutes or more.

"The consumption of carbohydrates before and during strenuous exercise not only improves endurance performance, but it can also minimise exercise-related immune disturbances," he said.

"Between 30 and 60 grams of carbohydrates every hour during exercise help to support normal immune function. Examples of carbohydrates that could be consumed during exercise include carbohydrate-containing fluids, gels and bars consisting of different carbohydrates such as glucose and fructose. Alternatively, bananas may also do the job.

"As general advice for people who train for and participate in endurance events, any products should be tested if they are tolerated in the field.

"Consuming carbohydrates in the first few hours immediately after strenuous exercise also helps to restore immune function. This is especially important in situations where the recovery duration between two consecutive exercise sessions is short, which is often the case for athletes."

The researches did not find sufficient evidence to recommend 'immune-boosting' supplements, for example antioxidants.

"A diversified and well-balanced diet is most likely sufficient to help maintain immune function following longer-term exercise training.

"Sleep is recognised as important for maintaining immune function. However more research is needed to understand the influence of sleep on immunity in athletes."


Physical activity should be routinely assessed during the doctor-patient encounter


A new study led by American Cancer Society researchers in collaboration with leading experts concludes that physical activity should be routinely assessed during the doctor-patient encounter, and that clinicians should design in collaboration with their patients a detailed physical activity plan with goals that should be set and monitored. The study uses concepts from public health and behavioral economics to provide practical advice to clinicians on effective counseling to patients.

The study appears early online in CA: A Cancer Journal for Clinicians. Below are highlights of the study:

  • Despite abundant evidence linking physical inactivity to increased risk for numerous chronic conditions, such as some types of cancer, heart disease, type 2 diabetes, stroke, and even depression, physical inactivity is prevalent in modern society.
  • In the United States, 51% of adults report not meeting aerobic physical activity guidelines, while objective measurement using accelerometers finds about 96.5% of adults ages 20 to 59 years do not meet those guidelines.
  • The study, led by Kerem Shuval, PhD, and Tammy Leonard, PhD reports that because physicians' advice is respected and physician-patient encounters are frequent, these meetings can be used to provide consistent and comprehensive physical activity counseling, which may be an important vehicle for reducing the risk of chronic diseases and premature death.
  • Physical activity should be routinely assessed at the clinic visit, a detailed physical activity plan should be jointly designed with the patient, and goals should be set and monitored.
  • Specific strategies should be provided to patients to overcome impediments to activity. Both conscious and unconscious factors affect patients' behaviors and should be taken into account by the clinician and patient.
  • Although the primary care setting is an important avenue to pursue physical activity promotion, it is not the only one. Policies aimed at changing the environment to one that is conducive to an active lifestyle are necessary to encourage sustainable changes.
"Physical activity is a modifiable behavior that has the potential to prevent numerous diseases, however, so many of us are not sufficiently active. Both conscious and unconscious factors are at play that influence our behavior." said Dr. Shuval. "It's difficult to choose activities we 'should' do over those we 'want' to do. Clinicians can help play a role in creating strategies, like encouraging the use of pre-commitment contracts, which impose constraints on our 'future selves' to act in a way the will benefit us in the long run."


Fasting diet lowers risks for major diseases


What if you could lose weight and reduce your risk of life-threatening disease without any changes in what you eat -- other than a five-day special diet once every few months?

That's what happened for 71 adults who were placed on three cycles of a low-calorie, "fasting-mimicking" diet. The phase II trial, conducted by researchers at the USC Leonard Davis School of Gerontology, demonstrated a host of benefits from the regimen.

The diet reduced cardiovascular risk factors including blood pressure, signs of inflammation (measured by C-reactive protein levels), as well as fasting glucose and reduced levels of IGF-1, a hormone that affects metabolism. It also shrank waistlines and resulted in weight loss, both in total body fat and trunk fat, but not in muscle mass.

In effect, the diet reduced the study participants' risks for cancer, diabetes, heart disease and other age-related diseases, according to the findings published Feb. 15 in Science Translational Medicine.

"This study provides evidence that people can experience significant health benefits through a periodic, fasting-mimicking diet that is designed to act on the aging process," said Valter Longo, director of the USC Longevity Institute and a professor of biological sciences for USC Davis and Dornsife. "Prior studies have indicated a range of health benefits in mice, but this is the first randomized clinical trial with enough participants to demonstrate that the diet is feasible, effective and safe for humans.

"Larger FDA studies are necessary to confirm its effects on disease prevention and treatment," he added.

One hundred people participated in the trial from April 2013 to July 2015. The participants, ages 20 to 70 and all generally healthy, were divided into two groups for the randomized trial.

Participants in the first group, the control group, were asked to continue their normal eating habits for three months. People in the second group were placed on a three-month test of the fasting-mimicking diet.

Those on the special diet were required to eat food products supplied by the nutrition company L-Nutra during the fasting periods of five days each month. The diet, which was designed to mimic the results of a water-only fast, allowed for participants to consume between 750 and 1,100 calories per day. The meals for the fast-mimicking diet contained precise proportions of proteins, fats and carbohydrates.

After three months, participants in the control group were moved onto the special diet.

The researchers found that participants on the fasting-mimicking diet lost an average of about 6 pounds. Their waistlines shrank by 1 to 2 inches. Their systolic blood pressure, which was in the normal range when the study began, dropped by 4.5 mmHG, while their diastolic blood pressure dropped by 3.1 mmHg. Also, their levels of IGF-1 dropped to between 21.7 ng/mL and 46.2 ng/mL, reaching a range associated with lower cancer risk.

"After the first group completed their three months on the fasting diet, we moved over participants in the control group to see if they also would experience similar results," Longo said. "We saw similar outcomes, which provides further evidence that a fasting-mimicking diet has effects on many metabolic and disease markers. Our mouse studies using a similar fasting-mimicking diet indicate that these beneficial effects are caused by multi-system regeneration and rejuvenation in the body at the cellular and organ levels.

"Our participants retained those effects, even when they returned to their normal daily eating habits," he added.

The researchers also noted that participants considered "at risk" because they had risk factors such as high IGF-1, cholesterol, blood pressure or blood sugar levels, made significant progress toward better health.

For example, baseline fasting glucose levels for participants with high blood sugar levels (putting them at risk for diabetes) dropped into the healthy range, below 99 mg/dl -- but these levels didn't drop among participants who already had healthy levels at the beginning of the study. Cholesterol was reduced by 20 mg/dl in those with high cholesterol levels, and by about 5 mg/dl in all participants.

"Fasting seems to be the most beneficial for patients who have the great risk factors for disease, such as those who have high blood pressure or pre-diabetes or who are obese," Longo said.

The researchers had invited participants in the study for one last set of tests three months later, at the end of the diet. The research team found that the beneficial effects -- from weight loss, smaller waistlines and lower glucose, blood pressure and IGF-1 levels -- were sustained.

The next step for researchers is a large, FDA phase III clinical trial to test the FMD on patients diagnosed with age-related diseases or at high risk for them. The researchers said further investigation will determine whether the benefits of the diet can continue for several months.


Postmenopausal hormone therapy exceeding ten years may protect from dementia


Postmenopausal estrogen-based hormone therapy lasting longer than ten years was associated with a decreased risk of Alzheimer's disease in a large study carried out at the University of Eastern Finland.

"The protective effect of hormone therapy may depend on its timing: it may have cognitive benefits if initiated at the time of menopause when neurons are still healthy and responsive," says Bushra Imtiaz, MD, MPH, who presented the results in her doctoral thesis.

The study explored the association between postmenopausal hormone replacement therapy, Alzheimer's disease, dementia and cognition in two nation-wide case-control studies and two longitudinal cohort studies. The largest study comprised approximately 230,000 Finnish women and the follow-up time in different studies was up to 20 years.

Menopause may explain women's higher dementia risk

Alzheimer's disease is the most common cause of dementia, and two out of three Alzheimer's cases are women. One possible explanation for women's higher dementia risk is the postmenopausal depletion of sex steroid hormones estrogen and progesterone. Estrogen receptors are present throughout the body including brain areas primarily affected in Alzheimer's disease. In in vitro and animal studies, estrogen has showed neuroprotective effects. However, studies on humans have yielded inconsistent results on the association between postmenopausal estrogen-based hormone replacement therapy and dementia risk.

Hormonal therapy may protect cognition if started at the onset of menopause

In the present study, long-term use of hormonal replacement therapy was associated with a better performance in certain cognitive domains - global cognition and episodic memory - and a lower risk of Alzheimer's disease. Short-term use was not significantly linked to dementia risk, but in one cohort, dementia risk was higher among short-term users who had started hormone therapy in the late postmenopausal period. The results were adjusted for various lifestyle, socioeconomic and demographic variables.

"In the light of these findings, hormonal replacement therapy may have a beneficial effect on cognition if started early, around the time of menopause. The protective effect of hormonal therapy may depend on the health status of neurons at baseline and may be lost if therapy starts years after menopause," Dr Imtiaz concludes.

The study also showed that the postmenopausal removal of ovaries, uterus or both was not significantly linked to the risk of Alzheimer's disease, irrespective of the indication of surgery or hormone therapy use.

The research data was from the MEDALZ (Medication use and Alzheimer's disease), OSTPRE (Kuopio Osteoporosis Risk Factor and Prevention Study) and CAIDE (Cardiovascular Risk Factors, Aging and Dementia) studies. The newest results were published recently in Neurology and Maturitas and the earlier results in the Journal of Alzheimer's Disease.


Using an air conditioner in summer may affect sleep quality



A study by a joint research team including professor Kazuyo Tsuzuki of Toyohashi University of Technology, Department of Architecture and Civil Engineering, National Institute of Advanced Industrial Science and Technology and Asahi Kasei Homes revealed that airflow from an air conditioner (AC) stimulates the human body while sleeping and impacts on sleep conditions even if the mean airflow velocity is lower than an insensible level. It suggests some AC setting may have an unintentional negative impact on sleep quality despite the comfort the person feels.

Urban warming blocks the temperature at night from cooling. It causes sweltering nights and deteriorates sleep quality. However, high-quality sleep can still be realized if the room temperature is controlled effectively with an AC. The general belief is that having the AC on all night is bad for health. Also, quite a few of us experience chills while sleeping and awakening due to cold temperature.

Airflow velocity in the sleeping environment can be configured with the AC. However, no data on airflow velocity measurement or research on the influence of AC airflow have been available.

The research team, led by professor Kazuyo Tsuzuki, had the subjects sleep in two bedrooms set to the same temperature using ACs set at different airflow velocities, then made a comparison of the depth of sleep and body temperature control using electroencephalogram (EEG) measurements as well as subjective reporting by the subjects.

We call the air velocity of 0.2m/s or lower "insensible airflow", in a sense, the person remains unaware of such a low level of airflow. In this study, a comparison was made on the influence of two types of airflow, mean velocity of 0.14 m/s (general AC) and 0.04 m/s (customized AC), both at a room temperature of 26 °C. Subjects felt cooler with the higher airflow velocity during wakefulness and sleep. However, no significant difference was observed in the feeling of comfort, length of sleep depth, skin temperature, rectal temperature or sense of warmth or coolness in each subject before sleeping.

General AC lowers airflow when the room temperature reaches the desired setting and starts increasing the flow again when the temperature is higher. The study compared the correlation between the timing of the airflow starting to blow and body movement, heart rate and waking stage in sleep depth. The results found that the subjects have significantly greater body movements, an increased heart rate and a higher frequency of waking in the room that has the AC with a mean velocity of 0.14 m/s. This suggests the general AC may have some influence on sleep, as we discovered that subjects roll over or their sleep depth changes the moment cool air blows out.

This study was conducted using healthy adult male subjects. It implies that the cold airflow may have a greater impact on the overall sleep of female and elderly subjects with lower physical strength or a greater sensitivity to cold. The result of this study is expected to be a useful clue as to how to configure the airflow velocity of an AC to create a comfortable sleeping environment.

This research is the result of the study conducted by Professor Kazuyo Tsuzuki at the National Institute of Advanced Industrial Science and Technology.

The research results were reported online in the Energy and Buildings journal on December 23, 2016.


Consuming saturated animal fats increases the risk of type 2 diabetes


Recently, dietary guidelines for the general population have shifted towards a plant-based diet (rich in legumes, whole-grain cereals, fruits, vegetables and nuts) and low in animal-based foods (like red meat and pastries). Increasing evidence is suggesting that plant-based diets are beneficial for health and they also have less impact on the environment.

Researchers at the Unit of Human Nutrition of the Universitat Rovira i Virgili (Tarragona-Spain), in collaboration with other centers from the PREDIMED Study and Harvard University, have evaluated the associations between total and subtypes of fat intake and the risk of type 2 diabetes. In addition, they have evaluated the relationship between food sources rich in saturated fatty acids and the incidence of type 2 diabetes.

The research's main findings showed that those participants who consumed higher amounts of saturated fatty acids and animal fat had a twofold higher risk of developing type 2 diabetes than those participants with a lower intake of saturated and animal fat. The consumption of 12 grams per day of butter was associated with a twofold higher risk of diabetes after 4.5 years of follow-up, whereas the intake of whole-fat yogurt was associated with a lower risk. The present study analyzed data from 3,349 participants in the PREDIMED Study who were free of diabetes at baseline but at high cardiovascular risk. After 4.5 years of follow-up, 266 participants developed diabetes.

This study will be published in the scientific journal The American Journal of Clinical Nutrition in February 2017 and was led by doctors Marta Guasch-Ferré;, researcher at Harvard T.H. Chan School of Public Health, Nerea Becerra-Tomás, researcher at the URV's Unit of Human Nutrition, and Jordi Salas-Salvadó;, who is head of the URV's Unit of Human Nutrition, Clinical Director of Nutrition at the Internal Medicine Service of the Sant Joan University Hospital in Reus, principal investigator at the CIBERObn, and member of the Pere Virgili Health Research Institute (IISPV).

According to the researchers, these findings emphasize the healthy benefits of a Mediterranean diet for preventing chronic diseases, particularly type 2 diabetes, and the importance of substituting saturated and animal fats (especially red and processed meat) for those found in vegetable sources such as olive oil and nuts.


A single high-fat meal can damage the metabolism


The global proliferation of overweight and obese people and people with type 2 diabetes is often associated with the consumption of saturated fats. Scientists at the German Diabetes Center (Deutsches Diabetes-Zentrum, DDZ) and the Helmholtz Center in Munich (HMGU) have found that even the one-off consumption of a greater amount of palm oil reduces the body's sensitivity to insulin and causes increased fat deposits as well as changes in the energy metabolism of the liver. The results of the study provide information on the earliest changes in the metabolism of the liver that in the long term lead to fatty liver disease in overweight persons as well as in those with type 2 diabetes.

In the current issue of the "Journal of Clinical Investigation", DZD researchers working at the German Diabetes Center, in conjunction with the Helmholtz Center in Munich and colleagues from Portugal, published a scientific investigation conducted on healthy, slim men, who were given at random a flavored palm oil drink or a glass of clear water in a control experiment. The palm oil drink contained a similar amount of saturated fat as two cheeseburgers with bacon and a large portion of French fries or two salami pizzas.

The scientists showed that this single high-fat meal sufficed to reduce the insulin action, e.g. cause insulin resistance and increase the fat content of the liver. In addition, changes in the energy balance of the liver were proven. The observed metabolic changes were similar to changes observed in persons with type 2 diabetes or non-alcoholic fatty liver disease (NAFLD). NAFLD is the most common liver disease in the industrial nations and associated with obesity, the so-called "metabolic syndrome," and is associated with an increased risk in developing type 2 diabetes. Furthermore, NAFLD in advanced stages can result in severe liver damage.

"The surprise was that a single dosage of palm oil has such a rapid and direct impact on the liver of a healthy person and that the amount of fat administered already triggered insulin resistance", explained Prof. Dr. Michael Roden, scientist, Managing Director and Chairman at the DDZ and the German Center for Diabetes Research (Deutsches Zentrum für Diabetesforschung, DZD). "A special feature of our study is that we monitored the liver metabolism of people with a predominantly non-invasive technology, e.g. by magnetic resonance spectroscopy. This allows us to track the storage of sugar and fat as well as the energy metabolism of the mitochondria (power plants of the cell)."

Thanks to the new methods of investigation, the scientists were able to verify that the intake of palm oil affects the metabolic activity of muscles, liver and fatty tissue. The induced insulin resistance leads to an increased new formation of sugar in the liver with a concomitant decreased sugar absorption in the skeletal muscles - a mechanism that makes the glucose level rise in persons afflicted with type 2 diabetes and its pre-stages. In addition, the insulin resistance of the fatty tissue causes an increased release of fats into the blood stream, which in turn continues to foster the insulin resistance. The increased availability of fat leads to an increased workload for the mitochondria, which can in the long term overtax these cellular power plants and contribute to the emergence of a liver disease.

The team of Prof. Roden suspects that healthy people, depending on genetic predisposition, can easily manage this direct impact of fatty food on the metabolism. The long-term consequences for regular eaters of such high-fat meals can be far more problematic, however.