Study: Iron consumption can increase risk for heart disease
A new study from the Indiana University School of Public Health-Bloomington has bolstered the link between red meat consumption and heart disease by finding a strong association between heme iron, found only in meat, and potentially deadly coronary heart disease.
The study found that heme iron consumption increased the risk for coronary heart disease by 57 percent, while no association was found between nonheme iron, which is in plant and other non-meat sources, and coronary heart disease.
The study was published online ahead of print in the Journal of Nutrition. Along with first author Jacob Hunnicutt, a graduate student in the school's Department of Epidemiology and Biostatistics, the study’s co-authors are Ka He and Pengcheng Xun, faculty members in the department.
Hunnicutt said the link between iron intake, body iron stores and coronary heart disease has been debated for decades by researchers, with epidemiological studies providing inconsistent findings. The new IU research, a meta-analysis, examined 21 previously published studies and data involving 292,454 participants during an average 10.2 years of follow-up.
The new study is unique because it looks at the associations of total iron consumption as well as heme and nonheme iron intake in comparison to the risk of coronary heart disease. The only positive association involved the intake of heme iron.
The body treats the two kinds of iron differently. It can better control absorption of iron from vegetable sources, including iron supplements, but not so with iron from meat sources.
"The observed positive association between heme iron and risk of CHD may be explained by the high bioavailability of heme iron and its role as the primary source of iron in iron-replete participants," the researchers wrote in the journal article. "Heme iron is absorbed at a much greater rate in comparison to nonheme iron (37 percent vs. 5 percent). Once absorbed, it may contribute as a catalyst in the oxidation of LDLs, causing tissue-damaging inflammation, which is a potential risk factor for CHD."
Iron stores in the body increase over time. The only way to reduce iron in the body is by bleeding, donating blood or menstruation. Some dietary choices, such as coffee and tea, also can inhibit iron absorption.
Indiana University neuroscientists Jonathon Crystal and Wesley Alford are zeroing in with increasing certainty on the notion that nonhuman animals have a particular type of memory known as "source memory," long seen as exclusively human.
In a new study, discussed in the journal Biology Letters, they were also surprised to discover that this type of memory in their animal subjects, in this case rats, also lasted much longer than memories have been known to last in any nonprimate.
The study could ultimately help us understand the biological underpinnings of source-memory impairment in humans and make possible new interventions for memory failure in such conditions as Alzheimer's, Huntington's, Parkinson's, schizophrenia, PTSD and depression. It also implies that source memory is evolutionarily quite old insofar as it exists in nonhuman animals.
Source memory, Crystal said, refers to the memory of how, where or by what means we acquired a piece of information. For instance, people typically want to remember who told them a certain joke, so they do not retell it to that same person. Or when entering a voting booth, voters may want to remember the source from which they heard a negative story about a candidate, a trusted newspaper or Comedy Central.
Source memory is a key component of the episodic memory that enables us to recall the discrete events, moments, situations that make up the life story we recognize as our own and that connects us to family, friends, community and the larger world. For this reason it is a kind of "holy grail" for researchers looking to pave the way for treating the diseases or disorders that afflict human memory, Crystal said.
"The main objective of this research is to prove that we are tapping into the kind of memory system that really matters to people affected by Alzheimer's disease," he said. "Otherwise we ultimately risk spending billions of dollars on a drug that will help you remember where you last put your reading glasses rather than one which enables you to remember your granddaughter's last visit and the news she shared with you, among other aspects of your life."
The key, Crystal said, is to lay out an experiment in which the rats cannot perform the specific task (of determining which arm in an eight-arm radial maze will replenish with chocolate pellets) without relying on source memory. In doing so, the study also showed that the memory they were measuring in the rat lasted much longer than anyone expected, up to seven days.
Crystal is the director of the Program in Neuroscience and the Comparative Cognition Lab in the IU Department of Psychological and Brain Sciences and College of Arts and Sciences. Alford recently left his position as a Visiting Scholar in the department and is currently a graduate student in neuroscience at Brandeis University.
Yoga, which can provide relaxation while combining strength training and deep stretches, is becoming a mainstream form of exercise in society. With this popularity have come many publications and online tutorials promoting yoga as a form of intense cardio exercise, one that some instructors caution against unless the practitioner has a strong background in the practice.
"Yoga is a personal experience," said Shelley Taylor, adjunct instructor of yoga at Indiana University School of Public Health-Bloomington's Department of Kinesiology. "Every individual body develops at a different pace, and it can never be a competition."
Taylor, who has taught yoga in Bloomington for more 30 years, specializes in a more "restorative style" of hatha yoga and believes this style allows the body to slowly maneuver into poses to prevent injuries. She recommends this style for any level of student.
"The purpose of yoga is not to create tension but to give attention to the areas of the body that need energy through the breath," she said.
Instead of viewing it as a rigorous workout, the key is to view it as connecting to the body rather than pushing the boundaries of the body, which is common in other forms of exercise. It is crucial to understand the proper way to do certain poses and the positive impact they can have on the body, as well as the many ways the poses may have a negative impact if performed inaccurately. Taylor said that taking a class with a qualified, experienced instructor will help the yoga student make sure the breathing, stretching and strengthening poses are being done correctly and safely. This can also eliminate any questions or doubts that may arise from exploring only on one's own.
"The best way to explain the experience is that it is about learning something deeper than what we see in the mirror," she said. "It's about acceptance, forgiveness and compassion for the mind and body you have today.
"Creating space and time for quiet contemplation and observation, and listening deeply to what is occurring in one's own mind and body, can be very informative. We all have wisdom within us, and yoga is a practice for tapping into that wisdom."
Here are more safety tips for yoga practice:
Practice yoga on a relatively empty stomach -- eat lightly one to two hours before class if needed.
Hydrate before, during and after yoga.
Listen to your own inner guidance and do what is best for you.
Breathe slowly, deeply and through the nostrils if possible.
Wear loose, comfortable (or stretchy) clothing and remove anything that might get in the way.
Do twisting poses from the right side of the body to the left to prevent digestion issues.
Women should refrain from doing inverted (upside down) poses while menstruating.