Could your brain cells be the next weapon to fight the obesity epidemic? Scientists from the UK believe it could happen. With over 30% of the population defined as obese and between 15-20% of children and teens in this category, the discovery is welcome news. Nicholas Dale, a neuroscience professor in Warwick and his team discovered a group of cells called tanycytes that talk to the brain directly and tell it to stop feeling hunger. Tanycytes are glial, non-neuronal cells found in the hypothalamus that may control body weight and energy levels. The cells have been discovered to control satiety, the feeling of fullness, based on certain nutrients in our food.
Scientists already knew that tanycytes could find glucose in cerebrospinal fluid, but new studies find that essential amino acids can trigger these cells to make us feel less hungry. Calcium imaging was used to make cells fluorescent and easier to track in vivo. Several essential and non-essential amino acids were added to the brain cells. Tanycytes reacted to lysine and arginine, two essential amino acids, by sending signals to the hypothalamus which controls appetite. After deleting genes which detect umami (savory) taste in mice, scientists discovered that tanycytes did not respond to the amino acids.
The scientists concluded that amino acids are identified by umami taste receptors, and coordinate the relationship between amino acids and the brain. Umami is responsible for savory taste in humans and most non-aromatic amino acids in rodents. According to professor Dale, “Amino acid levels in blood and brain following a meal are a very important signal that imparts the sensation of feeling full.” 1
Sources of lysine and arginine include meat, poultry, avocados, apricots, almonds, lentils, mackerel and plums. These foods could possibly make us feel fuller sooner. The scientists suggest that dietary interventions could alter hypothalamic brain circuits responsible for appetite. Research shows that tanycytes can make new neurons and can be remodeled by dietary interventions. 2 While more research is needed, it certainly can’t hurt to add lentils to your diet a few times per week, almonds, plums or apricots as snacks and fatty fish like mackerel into your meal plan. Add avocado to salads or sandwiches as well.
1. Greta Lazutkaite, Alice Soldà, Kristina Lossow, Wolfgang Meyerhof, Nicholas Dale. Amino acid sensing in hypothalamic tanycytes via umami taste receptors. Molecular Metabolism. DOI: http://dx.doi.org/10.1016/j.molmet.2017.08.015.
2. Timothy Goodman and Mohammad K. Hajihosseini. Hypothalamic tanycytes—masters and servants of metabolic, neuroendocrine, and neurogenic functions. Front Neurosci. 2015; 9: 387.
Look at any popular magazine these days and you’ll find at least one diet that bashes grains. Whether it’s Paleo, the Military diet or the “whole 30”, someone, somewhere is out there trying to get you to eat a bun-less sandwich. But what they may not realize is that anti-carb diets are a thing of the past. Grains are back, and for good reason.
You can’t argue with science, especially when done right. A recent study done at Tufts and published in the American Journal of Clinical Nutrition found that subjects consuming whole grains over refined grains burned more calories and absorbed less. In addition, glucose tolerance was improved in whole grain consumers. 1 Other studies have shown lower rates of obesity and cancer in individuals eating a diet containing whole grains. 2
Susan Roberts, a professor of nutrition at Tufts and author of http://www.instinctdiet.com believes Americans eat too many refined carbohydrates like white bread, pasta, pastries, and desserts, which contribute to overweight and obesity. Other scientists agree. Lauri Wright, an assistant professor in community and family health at the University of South Florida notes that whole grains are higher in antioxidants, which contribute to long term good health.
Rather than comparing weight changes in subjects, the Tufts study evaluated resting metabolic rate and energy (calorie) content in stool at the end of a 6-week study. Participants were on average, 50+ years of age with a BMI of 25.6, which is slightly above normal, but not overweight. Participants in both groups consumed about 2550 calories per day, but one group had 830 calories in whole grains while the other had 830 calories coming from refined grains. The study found that whole grain eaters burned 40 calories more than their refined grain counterparts and lost ~50 calories in stool, resulting in a 92-calorie deficit. If this deficit is carried over for a year, a 5.5 lb weight loss could be achieved. 1 A previous 2011 Harvard study of over 12,000 subjects in a whole grain study supported these results. 2
Most Americans miss the mark on fiber intake, consuming a mere 15 grams per day. The subjects in the Tufts study that ate whole grains ate about 39 grams of fiber daily versus 21 grams in the refined carbohydrate group. 1 Researchers believe the feeling of fullness in whole grain consumers affects the brains’ ability to regulate metabolism. Because your brain does not perceive that you are conserving energy, metabolism is not reduced. This is good news for carb lovers.
Making the switch to whole grains can be as easy. Swap brown rice or quinoa for white rice, or whole wheat pasta and bread for white bread or pasta. Try bran or wheat-based cereals in place of corn or rice. Whole grains are the new black.
Karl, J Philip, Meydani, Mohsen, Barnett, Junaidah, Vanegas, Sally, Goldin, Barry, Kane, Anne, Rasmussen, Helen, Saltzmn, Edward, Vangay, Pajau, Knights, Dan, Chen, C-Y Oliver, Das, Sai Krupa, Jonnalagadda, Meydani, Simin and Roberts, Susan. Substituting whole grains for refined grains in a 6-wk randomized trial favorably affects energy-balance metrics in healthy men and postmenopausal women. American J of Clinical Nutrition, February 8, 2017, doi: 10.3945/ajcn.116.139683
Mozaffarian, D, MD, Dr PH, Hao, Tao MPH, Rimm, Eric B, Willett, Walter MD, Dr PH, Hu, Frank MD, PhD. Changes in Diet and Lifestyle and long term weight gain in men and women. N Engl J Med 2011; 364:2392-2404. June 23, 2011
I tend to talk a lot about fiber. We’ve all heard that eating a diet high in fiber is linked with lower risk of disease. But, there’s something not quite right about high fiber Pop tarts or other foods like yogurt, which normally don’t contain fiber. New research suggests adding highly processed fiber to already processed foods may impact human health in a negative way, including a risk for liver cancer. This is based on research completed at Georgia State University and the University of Toledo. 1
There’s plenty of proof that eating foods naturally high in fiber is good for your health. Fiber from the skins and flesh of plant-based foods (whole grains, fruits, vegetables, beans, nuts and seeds) has been found to aid in weight management, cholesterol and blood sugar reduction and reduced risk for certain types of cancer. Fiber also aids in feeding the microbiota (good bacteria) in our bowels, which keeps our immune systems humming. 2 As health-conscious consumers recognize that their diets aren’t cutting the mustard as far as fiber goes, the food industry is enriching foods with refined soluble fibers like inulin. A recent US FDA ruling has allowed foods with supplemental fiber to be marketed as healthy. Serious concerns about the safety of these added fibers has been come to light in this study. 1
The initial research was to evaluate a diet enriched with refined inulin on obesity-associated risks with mice. Although a diet containing inulin to help reduce obesity risk, the mice began developing jaundice and after 6 months, many developed liver cancer. 1
Dr. Matam Vijay-Kumar- the senior author of the study from the University of Toledo found the results surprising, but was open to the challenge of investigating the healthy impact of processed soluble fiber. Despite the study being conducted in mice, it has potential ramifications for human health, cautioning against the addition of enriching processed foods with refined, fermentable fiber. 1
According to Dr. Andrew Gewirtz, one of the study’s authors and professor in the Institute for Biomedical Sciences at Georgia State, the research suggests that adding purified fibers to processed foods does not have the same health benefits of eating fruits and vegetables naturally high in soluble fiber. In fact, it may cause serious, life-altering liver cancer in some people. He believes that the FDA rule change which has encouraged marketing fiber-fortified food as healthy, is careless and should be better scrutinized. 1
In this study, chicory root, a form of inulin that we normally don’t consume, was used. The fiber goes through an extraction and chemical process. Rodents that developed liver cancer in the study were found to have previous dysbiosis or altered intestinal microbiota. This was suggested to play a vital role in the development of liver cancer. 1
This research suggests a need for further studies evaluating the effects of refined fiber, in particular on liver health.
The authors concluded that their research identified refined soluble fiber, while normally beneficial to good health, may also be harmful, leading to diseases like liver cancer, according to Dr. Benoit Chassaing, an assistant professor in the Neuroscience Institute of Georgia State. Fiber in general should not be seen as “bad” as the research sheds a light on fortified foods VS natural and that this type of fiber may be detrimental in some individuals with gut bacterial dysbiosis. 1
If you’re concerned about which fibers may be added to your foods, the following are FDA approved and considered safe.
- Beta-glucan soluble fiber, also called oat bran fiber
- Psyllium husk: a soluble fiber that may relieve constipation and help with diarrhea
- Cellulose: a non-soluble fiber that helps you to feel full, so you eat less
- Guar gum: a soluble fiber that is often used as a thickener in foods
- Pectin: a water-soluble fiber often added to jams and jellies
- Locust bean gum: also known as carob gum, a thickening agent found in sauces and cereals
- Hydroxypropylmethylcellulose: a soluble fiber that is found in some gluten-free foods 3
- Vishal Singh, Beng San Yeoh, Benoit Chassaing, Xia Xiao, Piu Saha, Rodrigo Aguilera Olvera, John D. Lapek, Limin Zhang, Wei-Bei Wang, Sijie Hao, Michael D. Flythe, David J. Gonzalez, Patrice D. Cani, Jose R. Conejo-Garcia, Na Xiong, Mary J. Kennett, Bina Joe, Andrew D. Patterson, Andrew T. Gewirtz, Matam Vijay-Kumar. Dysregulated Microbial Fermentation of Soluble Fiber Induces Cholestatic Liver Cancer. Cell, 2018; 175 (3): 679 DOI: 1016/j.cell.2018.09.004
- Slavin, J. Fiber and prebiotics: Mechanisms and health benefits. Nutrients. 2013 Apr; 5(4): 1417–1435.
If you’ve been hearing a lot about “taking care of your gut”, it has more to do with the inside of your abdomen than the paunch many Americans may be worried about losing before bikini season. Your gut, or biologically speaking, intestines, are the home to millions of strains of bacteria known collectively as microbiota or the gut microbiome. And just like snowflakes, everyone’s gut microbiota is uniquely different.
The bacteria in our guts is responsible for metabolizing nutrients from food, acting as a protective barrier against infections in the intestine and making fat-soluble vitamin K, which is needed to help make proteins that help clot blood. In addition, researchers are just scratching the surface about how the microbiome may impact health conditions such as arthritis, heart disease and cancer. 1
There are several factors that influence your gut microbiota including age, diet, genes, environment and medications, in particular antibiotics, which can significantly alter gut bacteria. Of these factors, diet may be the most controllable.
Microbes thrive on various components of food such as fiber. Some microbes make compounds that seems to keep us healthier, while others produce substances that may worsen our health. For example, a scientific study found a link between pediatric obesity and antibiotic use early in life. Research has shown that in mice, a diet high in fat increases gut permeability and raises gut absorption of endotoxins that foster weight gain, inflammation, obesity and diabetes. 2
Our gut microbiota is very complex and it’s difficult for scientists to identify which bacteria would be the most beneficial in preventing disease. According to Dr. Hohmann, who works in infectious diseases division at Harvard-affiliated Massachusetts General Hospital, a few dietary tweaks may make a big difference, though gut microbiota change slowly over time and not overnight. She suggests adding the following foods to our diets:
- Fermented foods that contain natural probiotics include miso, yogurt, kefir and kimchi. Sauerkraut and pickles are also fermented, but may need to be limited in those with high blood pressure due to high sodium content.
- High fiber, complex carbohydrates such as beans, lentils, whole grain breads, cereals and grains such as barley, bran, bulgur, farrow and quinoa. The more variety of plant-based foods, the more diverse our bacteria become. 3
While it may be tempting to take an over the counter pro-biotic and call it a day, scientists suggest that probiotics do not typically change the gut microbiota on a permanent basis. Research indicates that a few strains of probiotics have been found to modify the gut, but once they’re stopped, the gut microbiome may reverse back to its previous state. Probiotics may be useful in treating loose stool related to antibiotic use, but for the most part, the data of their effectiveness is not very convincing. 4
Until research proves otherwise, our best bet for a healthy gut is to eat a high fiber, plant-based diet with fewer servings of high fat animal foods, salt and refined carbohydrates. This will not only improve the inside of our guts, but may also give us a more flattering gut on the outside.
- Kei E Fujimura, Nicole A Slusher, Michael D Cabana, and Susan V Lynch, PhD Role of the gut microbiota in defining human health. Expert Rev Anti Infect Ther. 2010 Apr; 8(4): 435–454.
- Cani P. et. al. Diabetes 2008; 57: 147-81.
- Mary Ellen Sanders. How do we know something called “Probiotic” is really a probiotic? A guideline for consumers and health care professionals. Functional Food Reviews 2009: 1; 3-12.