Changes in the immune system explain why belly fat is bad for thinking
December 17, 2019
Science Daily/Iowa State University
Researchers have found for the first time that less muscle and more body fat may affect how flexible our thinking gets as we become older, and changes in parts of the immune system could be responsible.
These findings could lead to new treatments that help maintain mental flexibility in aging adults with obesity, sedentary lifestyles, or muscle loss that naturally happens with aging.
The study, led by Auriel Willette, assistant professor of food science and human nutrition, and Brandon Klinedinst, a PhD student in neuroscience, looked at data from more than 4,000 middle-aged to older UK Biobank participants, both men and women. The researchers examined direct measurements of lean muscle mass, abdominal fat, and subcutaneous fat, and how they were related to changes in fluid intelligence over six years.
Willette and Klinedinst discovered people mostly in their 40s and 50s who had higher amounts of fat in their mid-section had worse fluid intelligence as they got older. Greater muscle mass, by contrast, appeared to be a protective factor. These relationships stayed the same even after taking into account chronological age, level of education, and socioeconomic status.
"Chronological age doesn't seem to be a factor in fluid intelligence decreasing over time," Willette said. "It appears to be biological age, which here is the amount of fat and muscle."
Generally, people begin to gain fat and lose lean muscle once they hit middle age, a trend that continues as they get older. To overcome this, implementing exercise routines to maintain lean muscle becomes more important. Klinedinst said exercising, especially resistance training, is essential for middle-aged women, who naturally tend to have less muscle mass than men.
The study also looked at whether or not changes in immune system activity could explain links between fat or muscle and fluid intelligence. Previous studies have shown that people with a higher body mass index (BMI) have more immune system activity in their blood, which activates the immune system in the brain and causes problems with cognition. BMI only takes into account total body mass, so it has not been clear whether fat, muscle, or both jump-start the immune system.
In this study, in women, the entire link between more abdominal fat and worse fluid intelligence was explained by changes in two types of white blood cells: lymphocytes and eosinophils. In men, a completely different type of white blood cell, basophils, explained roughly half of the fat and fluid intelligence link. While muscle mass was protective, the immune system did not seem to play a role.
While the study found correlations between body fat and decreased fluid intelligence, it is unknown at this time if it could increase the risk of Alzheimer's disease.
"Further studies would be needed to see if people with less muscle mass and more fat mass are more likely to develop Alzheimer's disease, and what the role of the immune system is," Klinedinst said.
Starting a New Year's resolution now to work out more and eat healthier may be a good idea, not only for your overall health, but to maintain healthy brain function.
"If you eat alright and do at least brisk walking some of the time, it might help you with mentally staying quick on your feet," Willette said.
https://www.sciencedaily.com/releases/2019/12/191217141531.htm
This is how belly fat could increase your cancer risk
August 24, 2017
Science Daily/Michigan State University
A new study now offers new details showing that a certain protein released from fat in the body can cause a non-cancerous cell to turn into a cancerous one. The research also found that a lower layer of abdominal fat, when compared to fat just under the skin, is the more likely culprit, releasing even more of this protein and encouraging tumor growth.
It's been well established that obesity is a contributor to cancer risk, but how it actually causes cancer is still a question that hasn't been fully explained.
A new Michigan State University study now offers new details showing that a certain protein released from fat in the body can cause a non-cancerous cell to turn into a cancerous one. The federally funded research also found that a lower layer of abdominal fat, when compared to fat just under the skin, is the more likely culprit, releasing even more of this protein and encouraging tumor growth.
"While there have been several advances in treating cancer and improving the quality of life of patients, the number of new cases continues to surge," said Jamie Bernard, lead author and an assistant professor in pharmacology and toxicology.
"It's important to understand the cause so we can do a better job at reducing the number of cancer cases using dietary modifications or therapeutic interventions."
It's estimated that more than one-third of the population is obese. Obesity has been linked to several types of cancers including breast, colon, prostate, uterine and kidney, but Bernard indicated that just being overweight isn't necessarily the best way to determine risk.
"Our study suggests that body mass index, or BMI, may not be the best indicator," Bernard said. "It's abdominal obesity, and even more specifically, levels of a protein called fibroblast growth factor-2 that may be a better indicator of the risk of cells becoming cancerous."
There are two layers of belly fat. The top layer, known as subcutaneous fat, lies right under the skin. The layer under that, called visceral fat, is the one she found to be more harmful.
Bernard and her co-author Debrup Chakraborty, a postdoctoral student in her lab, studied mice that were fed a high-fat diet and discovered that this higher-risk layer of fat produced larger amounts of the fibroblast growth factor-2, or FGF2, protein when compared to the subcutaneous fat. They found that FGF2 stimulated certain cells that were already vulnerable to the protein and caused them to grow into tumors.
She also collected visceral fat tissue from women undergoing hysterectomies and found that when the fat secretions had more of the FGF2 protein, more of the cells formed cancerous tumors when transferred into mice.
"This would indicate that fat from both mice and humans can make a non-tumorigenic cell malignantly transform into a tumorigenic cell," Bernard said.
She added that there are several other factors released from fat, including the hormone estrogen, that could influence cancer risk, but many of those studies have only been able to show an association and not a direct cause of cancer. She also said genetics plays a role.
"There's always an element of chance in whether a person will get cancer or not," Bernard said. "But by making smarter choices when it comes to diet and exercise and avoiding harmful habits like smoking, people can always help skew the odds in their favor."
Bernard indicated that she is already looking at identifying new anti-cancer compounds in her research that could stop the effects of FGF2.
https://www.sciencedaily.com/releases/2017/08/170824101756.htm