Feeling Close To A Friend Increases Progesterone, Boosts Well-being And Reduces Anxiety And Stress

Why does dishing with a girlfriend do wonders for a woman's mood?

A University of Michigan study has identified a likely reason: feeling emotionally close to a friend increases levels of the hormone progesterone, helping to boost well-being and reduce anxiety and stress.

"This study establishes progesterone as a likely part of the neuroendocrine basis of social bonding in humans," said U-M researcher Stephanie Brown, lead author of an article reporting the study findings, published in the current (June 2009) issue of the peer-reviewed journal Hormones and Behavior.

A sex hormone that fluctuates with the menstrual cycle, progesterone is also present in low levels in post-menopausal women and in men. Earlier research has shown that higher levels of progesterone increase the desire to bond with others, but the current study is the first to show that bonding with others increases levels of progesterone. The study also links these increases to a greater willingness to help other people, even at our own expense.

"It's important to find the links between biological mechanisms and human social behavior," said Brown, is a faculty associate at the U-M Institute for Social Research (ISR) and an assistant professor of internal medicine at the U-M Medical School. She is also affiliated with the Ann Arbor Veterans Affairs Hospital. "These links may help us understand why people in close relationships are happier, healthier, and live longer than those who are socially isolated."

Progesterone is much easier to measure than oxytocin, a hormone linked to trust, pair-bonding and maternal responsiveness in humans and other mammals. Oxytocin can only be measured through an invasive spinal tap or through expensive and complex brain imaging methods, such as positron emission tomography scans. Progesterone can be measured through simple saliva samples and may be related to oxytocin.

In the current study, Brown and colleagues examined the link between interpersonal closeness and salivary progesterone in 160 female college students.

At the start of the study, the researchers measured the levels of progesterone and of the stress hormone cortisol in the women's saliva, and obtained information about their menstrual cycles and whether they were using hormonal contraceptives or other hormonally active medications.

To control for daily variations in hormone levels, all the sessions were held between noon and 7 p.m.

The women were randomly assigned to partners and asked to perform either a task designed to elicit feelings of emotional closeness or a task that was emotionally neutral.

In the emotionally neutral task, the women proofread a botany manuscript together.

After completing the 20-minute tasks, the women played a computerized cooperative card game with their partners, and then had their progesterone and cortisol sampled again.

The progesterone levels of women who had engaged in the emotionally neutral tasks tended to decline, while the progesterone levels of women who engaged in the task designed to elicit closeness either remained the same or increased. The participants' cortisol levels did not change in a similar way.

Participants returned a week later, and played the computerized card game with their original partners again. Then researchers measured their progesterone and cortisol. Researchers also examined links between progesterone levels and how likely participants said they would be to risk their life for their partner.

"During the first phase of the study, we found no evidence of a relationship between progesterone and willingness to sacrifice," Brown said. "But a week later, increased progesterone predicted an increased willingness to say you would risk your life to help your partner."

According to Brown, the findings are consistent with a new evolutionary theory of altruism which argues that the hormonal basis of social bonds enables people to suppress self-interest when necessary in order to promote the well-being of another person, as when taking care of children or helping ailing family members or friends.

The results also help explain why social contact has well-documented health benefits---a relationship first identified nearly 20 years ago by U-M sociologist James House.

"Many of the hormones involved in bonding and helping behavior lead to reductions in stress and anxiety in both humans and other animals. Now we see that higher levels of progesterone may be part of the underlying physiological basis for these effects," Brown said.

Chicken Meat: Organic Acids, Plant Extracts And Irradiation Combine To Beat The Bacteria

A mixture of some organic acids and some extracts from plants turns out to be enough to greatly reduce pathogenic bacteria on chicken breast meat. Add some irradiation to the mix and it makes a lethal combination against the bacteria.Food Safety Consortium researchers at the University of Arkansas System’s Division of Agriculture found that they could greatly reduce E. coli O157:H7, Listeria monocytogenes and Salmonella Typhimurium in the chicken breast meat by infusing combinations of organic acids – acetic, citric, lactic, malic and tartaric – into the meat. The experiments were also performed with extracts from green tea and grape seeds in combination with the acids.

Three of the organic acids – malic, citric and tartaric – were most effective against S. Typhimurium and E. coli O157:H7, more than against L. monocytogenes. With irradiation factored in, the results were significant against all the pathogens.

“We want to determine the least amount of plant extracts that we can use and the least amount of irradiation dosage to get the best inhibitory effect,” said Navam Hettiarachchy, a UA food science professor who supervised the project.

Previous research by Hettiarachchy’s research team showed that extracts from grape seed and green tea reduced L. monocytogenes to undetectable levels when applied in combination with nisin, a bacteriocin recognized as a safe food preservative.

The researchers are also using the plant extracts to serve as antioxidants, which minimizes lipid oxidation. Lipid oxidation is a process that causes meat quality to deteriorate by adversely affecting characteristics such as flavor, color and texture.

Hettiarachchy said the research team has examined the effects of irradiation on the chicken’s color and texture and found no significant change.

The research is continuing, but Hettiarachchy said a poultry company has already expressed interest in the project’s findings. Irradiation, however, has not yet been applied widely in the United States as many companies have worried about potential resistance among consumers.

Hettiarachcy suggested that labels on irradiated products could have a brief explanation of irradiation to educate consumers.

“I am hopeful that with time the public will become aware of irradiation processing so that they accept irradiation in processing poultry and meat products for safety against pathogens,” Hettiarachchy said. “A new education component is very important and may be the key for acceptance for irradiated food products by the consumer.”

Stem Cells Transplanted From Marrow Into Heart May Improve Heart's Performance

The Cardiology department and the Area of Cell Therapy of Cordoba hospital Reina Sofia are carrying out clinical tests with patients who have suffered from a severe heart attack. With the implantation of the patient's stem cells, the heart regenerates thus improving its wall motion, that is, its cardiac performance. Indeed for the last four years, the Area of Cell Therapy of Cordoba hospital, led by haematologist Dr. Concha Herrera, has been implementing a therapy program with adult stem cells in patients with heart-related problems. However, this therapy is not a service the hospital offers yet. More specifically, at the end of 2007 the hospital ended a clinical test with patients who had suffered a severe myocardial infarction, that is, an obstruction of one of the main coronary arteries that stops the blood pump to the heart.

The test consisted of treating 30 people split into three groups of ten each at random. The first group was the control group, where patients received standard treatment for acute myocardial infarction; the second group was treated with stem cells directly implanted into the coronary artery affected using a catheterization; the third group was treated with a medicine called G-CSF, which makes cells move from the marrow to the blood, so that they get to the heart in a natural way, without having to do so through a catheter.

At the end of the test, the results revealed that the two groups treated without cells improved slightly, whereas patients transplanted with stem cells through the coronary arteries (vessels which bring the blood to the Herat muscle) did improve their ventricular function much more. This was interpreted as a significant decrease of the cardiac failure symptoms such as pain, fatigue and breathlessness when making small efforts.

Moreover, with this process it is possible to prevent some acute arrhythmias (change or irregularity in the rhythm of the heartbeat), which in many cases could result in the patient's death. ‘However, it does not prevent a future heart attack', Dr. Herrera assures.

In short, the stem cells transplanted from the marrow into the heart muscle have a double function: on the one hand they regenerate the heart cells, the cardiomiocites. In addition to this, they segregate a series of proangiogenic factors that produce blood vessels (angiogenesis) and can also produce the recruitment of stem cells that are in the myocardium itself.

The Are of Cell Therapy, led by Dr. Herrera, is currently developing other trials in the cardiology department, both in patients with acute myocardial infarction (35) and in those with chronic ischemic cardiopathy, due to one or more heart attacks suffered in the past, either months or years ago (20 patients). Moreover, in the last few months a new clinical trial has been started - so far in eight patients- who suffer from a disease called Dilated Myocardiopathy. The origin of this disease is unknown but it causes a very severe cardiac failure which conditions the need for a heart transplant in many cases. So far, ‘the results in these first patients are very satisfactory'.

'We will start shortly a clinical test where we will use stem cells from the marrow in diabetic patients who have the artery taking the blood to the lower limbs blocked. This pathology, called peripheral ischemia, can result in a limb being amputated'.

This work, published in Revista Española de Cardiología journal, has been awarded with a prize by the Sociedad Española de Cardiología.