A symposium chaired by Bahram Arjmandi, PhD, RD, and Carmen Castaneda-Sceppa, MD, PhD, provided insights into the etiology and pathophysiology of osteosarcopenic obesity, and presented suggestions for pharmacological and dietary treatment strategies.
Jasminka Ilich-Ernst, PhD, RD, a professor at Florida State University, outlined the problem and scope of osteosarcopenic obesity, a term first coined in 2012. Characterized by the coexistence of three distinct musculoskeletal disorders—osteopenia/osteoporosis, sarcopenia, and obesity—osteosarcopenic obesity is a complex condition, for which the proof-of-concept was established only recently.
A major concern with osteosarcopenic obesity, Ilich-Ernst said, lies in age-related fat redistribution and subsequent infiltration into bone and muscle. Typically bone, muscle, and fat progenitor cells differentiate in a balanced distribution to enable normal tissue development. But with aging, a sedentary lifestyle, poor nutrition, and low-grade inflammation, differentiation patterns become altered and fat production predominates.
Whereas current nutritional and lifestyle management recommendations address the individual components of osteosarcopenic obesity, they do not address the collective triad. Ilich-Ernst suggested adhering to current recommendations to achieve peak bone mass before age 30, gain and maintain adequate muscle mass, and maintain a health weight, but she added that increasing dietary protein to 25 percent of total energy and limiting carbohydrate consumption to approximately 40 percent of total energy might further reduce risk of developing osteosarcopenic obesity.
Further insights into the interconnected nature of bone, muscle, and fat were provided by Clifford J. Rosen, MD, a professor of medicine at Tufts University and research scientist at the Maine Medical Center Research Institute. Rosen explained that the three tissues derive from a single progenitor cell type, and their responses to various cytokines, hormones, and regulatory input, primarily the sympathetic nervous system, are similar.
He then described newly identified “beige,” or brown-like, adipocytes, which contain more mitochondria and are more thermogenic than classic white adipocytes. Beige adipocytes share a common progenitor cell with smooth muscle. As such, they can be viewed as a sort of “hybrid” between fat and muscle cells. Intermittent cold exposure induces beige adipogenesis, a process referred to as “browning,” and promotes weight loss by increasing sympathetic tone—a potential non-pharmacological approach to body fat loss.
However, Rosen noted, whereas sympathetic tone enhances fat loss, it uncouples the process of bone remodeling, promoting bone loss. He added that many of the new classes of drugs that target beige adipogenesis might have similar, deleterious off-target effects on bone.
Ronenn Roubenoff, MD, MHS, of Novartis Institutes for Bone Research, and a professor of medicine and nutrition at Tufts University, compared the effects of dietary versus pharmacological approaches to treating sarcopenia. Sarcopenia, Roubenoff said, is an age-related loss of muscle mass due to type II muscle fiber atrophy. He said that preventing sarcopenia might increase life span and improve quality of life in older adults.
Although some research suggests increasing dietary protein intake might reduce muscle wasting, few data support changing current recommendations, Roubenoff said. In addition, the muscle-sparing effects of dietary protein differ in women versus men. Whereas women benefit from increased intake, men (who experience a U-shaped curve in response to intake) benefit from more moderate intake.
Roubenoff added that muscle, unlike other organs, doesn't senesce; rather, it remains plastic, providing the potential for older adults to regain muscle mass and function. However, muscle in older adults exhibits “anabolic resistance”—an inability to integrate and build muscle. Emerging pharmacological approaches target this resistance to reverse muscle wasting.
Finally, Wayne Campbell, PhD, a professor of nutrition science at Purdue University, described the differential effects of dietary protein intake during weight loss on bone, muscle, and fat. Specifically, Campbell addressed the question of how older adults can purposefully lose weight without compromising musculoskeletal function.
Campbell and his colleagues analyzed NHANES data from 1999-2004, a period that included dual energy X-ray absorptiometry data. They partitioned the data based on thresholds of the Recommended Dietary Allowance regarding bone health, and noted that whereas inadequate protein intake had an adverse effect on bone health in adults over age 50, high protein had variable effects. Campbell then described his research with whey supplementation and noted that groups that consumed higher amounts of a whey protein supplement lost more fat than groups consuming lesser amounts. However, they experienced no change in bone status, consistent with the epidemiological data.
At a minimum, Campbell said, adults should consume adequate protein. But he added that high dietary protein intake during weight loss has a positive effect on body composition, inducing greater fat loss while maintaining lean muscle mass. In addition, he noted that high protein intake has variable effects, depending on protein type. In particular, whereas protein from dairy and plant sources likely provides greater benefit to bone, protein from non-dairy animal sources likely benefits soft tissue.
Researchers are using carrots to produce a new tracer that will help scientists study vision and brain function. The results of this study were presented in the “Carotenoid and Retinoid Interactive Group: Bioavailability and Metabolism of Carotenoids and Vitamin A” on March 29 by Joshua Smith and John Erdman, PhD, from the University of Illinois at Urbana-Champaign.
Lutein is a carotenoid which accumulates in the retina of the eye and may protect the eyes from damage, especially age-related macular degeneration. It also accumulates in certain areas of the brain and may be beneficial for cognitive performance. However, little is known about how lutein accumulates in tissues such as the brain or how these tissues metabolize it. This led researchers to embark on a mission to develop lutein labeled with a non-radioactive, stable tracer (carbon-13) as a tool to study the metabolism of lutein in tissues.
Enter the colorful carrots. Carrots are a good source of lutein, but the amount of lutein can vary depending on the variety of carrot. Researchers tested seven different carrot cultivars that ranged in color from red to yellow to purple to see which one produced the most lutein. Then they had to culture the carrot cells in flasks and optimize the growing conditions to increase lutein production.
Once they figured out the optimal growing conditions, the carrot cells were fed carbon-13 labeled glucose. The lutein then had to be extracted using reverse-phase high performance liquid chromatography, and incorporation of the carbon-13 tracer was assessed using mass spectrometry. Approximately 58% of the lutein extracted from the carrot cells was uniformly labeled with carbon-13.
So what's next for this new tracer lutein? The researchers plan to use it to study tissue accumulation of lutein in animal models before embarking on any studies in humans. They will also be going back to the lab bench to see if there are any more changes they can make to further improve their lutein yield.
This research was funded by a grant from Abbott Nutrition through the Center for Nutrition, Learning, and Memory at the University of Illinois.
Systematic reviews are the basis for nutrition policy and guidance, but gaps in the evidence base can impact recommendations. Presenters at the symposium “Creating the Future of Evidence-Based Nutrition Recommendations, Using Lipid Research Case Studies” sponsored by ILSI North America spoke on various aspects that inform the process of developing dietary guidance and its implementation on Saturday, March 28. Major policy and regulatory groups such as the Dietary Guidelines for Americans Scientific Advisory Committee, American Heart Association, and the Institute of Medicine use systematic reviews as the basis for their decision making, but often the ability to make recommendations can be hampered by a lack of strong evidence.
The process of developing evidence-based reviews, such as the one used by the USDA Nutrition Evidence Library, must be rigorous, transparent, and minimize bias, because these reviews inform federal nutrition policy and programs. At the outset, key systematic review questions are developed which should reflect important decisional dilemmas in public health nutrition guidance.
The next critical step is deciding on inclusion and exclusion criteria, which determines what literature is included in the evidence base. Criteria that may be considered include study design, study duration, size of groups, drop out rates, and the health status of participants. This process is thoroughly documented and transparent so it can easily be determined why a study was included or excluded. The evidence base will go on to be evaluated by expert panels in order to make recommendations and guidances.
How can scientists ensure that their research is included in the evidence base?
- When designing studies, it is important to consider the validity of the study design, the impact of endpoints, and the relevance and feasibility of interventions. Are the outcomes meaningful and are they translatable? If not, what additional information do you need? Researchers can also use the gaps in the literature identified in Nutrition Evidence Library systematic reviews to inform future investigations.
- If studying chronic disease risk, use validated surrogate biomarkers.
- Carefully consider your comparator group. One of the most common reasons studies are discounted from systematic reviews is they did not include appropriate control groups.
- Once you are ready to report your results, follow established reporting standards such as the Consolidated Standards of Reporting Trials (CONSORT) for randomized clinical trials or the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines. This can help ensure that key information is included and is available for data abstraction in future systematic reviews and meta-analyses.
- Participate in the process. Once draft reports such as the Dietary Guidelines for Americans Scientific Report are issued, there is the opportunity for public comment. Feedback from scientists with expertise is strongly encouraged.
ASN's Scientific Sessions & Annual Meeting began on Saturday morning with a minisymposium on Nutrition and Cognitive and Neurological Outcomes. Researchers presented studies looking at a range of outcomes across the life course, from infants to the elderly.
Focusing on infants and preschool aged children, Sylvia Fernandez-Rao of the National Institutes of Health shared results from a randomized trial in India, in which participants received one of four interventions: micronutrient powders (MNPs), an early learning intervention, a combination of MNP + early learning, or neither. The results showed small improvements in some categories of development from both the MNP and early learning intervention but no evidence of additive effects.
Karim Bougma of McGill University presented results of a randomized trial of salt iodization in Ethiopia. The study enrolled children up to age five and distributed iodized salt in intervention communities. They found a significant difference between intervention and control areas in several measures of child development and also in maternal depression symptoms. This was true despite a significant increase in consumption of iodized salt in control areas as well as variable quality of salt iodization.
Moving on to older children, Beth Prado of UC-Davis presented results from a study that re-enrolled children ages 9-12 years whose mothers had received multiple micronutrient (MMN) supplementation while pregnant. They found that maternal MMN supplementation had small but significant positive effects on cognitive domains that were still measurable up to 12 years later. They additionally found that the cognitive benefits of MMN varied based on the mother's nutritional status.
Looking at young adults, Susan Emmett of Johns Hopkins University spoke about nutrition and hearing loss. She used data from the Nepal Nutrition Intervention Project, a randomized trial of preschool vitamin A supplementation that began in 1989. The project followed children and collected data every four months, including about any ear discharge in the previous week. Among children who had at least one episode of ear discharge, vitamin A supplementation was associated with a 42% risk reduction of young adult hearing loss.
Usha Ramakrishnan of Emory University also presented data on adults, specifically mothers. She described a randomized trial in Viet Nam, in which women received weekly pre-conceptional supplements of folic acid, iron-folic acid, or multiple micronutrients. The outcome of interest was maternal depression, but researchers found very few symptoms of postpartum depression, and there was no difference between treatment groups.
Finally, Alex Brito of UC-Davis spoke about a randomized trial of vitamin B12 in Chile, which measured neurophysiological outcomes among adults ages 70-79 years. The researchers found significant improvements in nerve conduction velocity with B12 intake but no improvements in other neurophysiological outcomes.
The minisymposium reflected just some of the diversity of interventions and outcomes within the very broad topic of nutrition and cognitive and neurological outcomes. It made clear that, as with many topics at EB 2015, this area is rich with future research opportunities, and there is still much to learn.
Read the entire issue here or find copies throughout the Convention Center in Boston.
ASN's Scientific Sessions & Annual Meeting on Sunday, March 29. In the linked interview she describes her career path and shares how she uses the dietary guidelines in her practice.
Running on Empty – Is There a Metabolic or Cognitive Benefit to the Morning Meal?” session at ASN's Scientific Sessions on March 29, the Kent State assistant professor of psychology will explain why, from a cognitive standpoint, it's best not to miss this meal. In the following interview she talks to ASN about what constitutes a breakfast; what it will take to sell the public on the benefits of eating when they wake up; and what is lacking in the current research on the topic. Read the entire text and leave your questions for Mary Beth in the comments.
Nutrition may be a relatively young science, but perhaps the intuition of our elders has informed us more than we realize. Food superstitions are as old as culture itself and essentially every civilization has added its share to the ever-growing list of dos and don'ts. In respect to two months in a row with Friday the 13ths this year, I investigated how some long-standing tales about what we eat might actually be grounded in truth.
Spilling salt brings bad luck. This widely recognized superstition originating in ancient Greece may hold some hidden truths. One of the most commonly believed concepts about sodium (salt) today is that eating too much can aggravate conditions such as hypertension, cardiovascular disease, and chronic kidney disease. The American Heart Association and National Kidney Foundation recommend limiting salt consumption to about 1,500 mg/d. So whether you believe the superstition or modern medicine, you will think twice and shake the habit of spilling salt onto your meal.
Eating garlic, onions, and mustard seeds is good luck by granting blessings or warding off evil. This superstition is rooted in many proverbs, and it just so happens that vegetables in the Amaryllis (onions, garlic, etc) and Brassicaceae (mustard, broccoli, etc) families are being investigated as anticarcinogens. Many of the naturally occurring phytochemicals in these plants may serve to halt the formation of cancer causing compounds, enhance repair of damaged DNA, and induce apoptosis of tumor cells. Chowing down on these luckily talismans could ward off disease, but don't forget that those same beneficial compounds may also scare off your friends with the odors they leave lingering behind.
Bringing bananas on a boat will cause fishermen ill will and a bad catch. Green bananas, coincidentally, may just cause some unwanted symptoms of illness. Un-ripened bananas are a good source of resistant starch. Depending on your personal disposition, fermentation of resistant starch could either provide a healthy dose of short-chain fatty acids to the intestines, or a healthy dose of gas and diarrhea. Any angler would have difficulty landing the big one between frequent trips to the loo, and that's no fish tale.
Planting parsley will help a woman become pregnant. Of course having good nutrition is important for increasing chances of beginning a pregnancy, but parsley is specifically of interest for the health of the newly developing fetus. This ubiquitous herb is a good source of many vitamins and minerals, including folic acid. In the first few weeks, adequate folate is especially important for preventing neural tube defects in the rapidly growing baby. Consider sowing seeds of parsley before sowing your wild oats.
Every day we find out more and more about how our eating habits affect our bodies, but in some cases we shouldn't overlook what prior generations have already provided us. Tell the researchers and your grandma thanks for the advice.
1. Cobb, L.K., Anderson, C.A.M., Elliott, P., et al. Methodological issues in cohort studies that relate sodium intake to cardiovascular disease outcomes: A science advisory from the American Heart Association (2014) Circulation, 129 (10), pp. 1173-1186. http://www.scopus.com/inward/record.url?eid=2-s2.0-84895928005&partnerID=40&md5=75ecd90a4f86d73a8c200d300b4ca6c8