Thursday, October 17, 2013


The identification that the bacteria in our guts play critical roles in whole body metabolic and immune homeostasis has led to an explosion of scientific research in this field (intestinal microbiota) as well as to increased interest in developing food products that can deliver beneficial bacteria (probiotic) to the gut. I have written on this subject before in my blog as well as discussed some of the details of how bacteria play a role in the metabolic processes involved in the development of obesity and type 2 diabetes.

A recent paper, published in the journal Nature Communications, demonstrates another highly interesting angle to the roles gut microbiota play in the development of obesity and diabetes:

In this study the investigators expanded on an observation that the antioxidant and radiation protectant molecule, tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl), demonstrated an ability to prevent obesity in mice. Another related study demonstrated that tempol administration was associated with an altered metabolome (products of global metabolism) evidenced by alterations in gut-derived metabolic compounds. Related information has previously shown a correlation between the gut microbiome and their effects on metabolic pathways elsewhere in humans such as bile acid and fatty acid metabolism. The two predominant bacterial phyla in the human gut are Firmicutes and Bacteroidetes and the relative abundance of these two populations have been shown to be altered in obesity.

In the current study the investigators found that tempol administration, in mouse chow, preferentially reduced the levels of bacteria from the genus Lactobacillus (of the Firmicutes phylum). Associated with the reduction in Lactobacillus was a decrease in the level of the bile salt hydrolase (BSH) activity of this strain of bacteria. The reduced BSH activity was associated with an increase in the gut level of the bile acid metabolite tauro-beta-muricholic acid (T-b-MCA). T-b-MCA is a known antagonist of the nuclear receptor: farnesoid X receptor (FXR). FXR is a critical transcriptional co-regulator involved in the control of bile acid, lipid, and glucose homeostasis. For more detailed information on the activities of FXR go to the FXR page of The feeding of tempol to experimental obese mice in this study was correlated to reduced levels of obesity and reduced levels of insulin resistance even when the animal were fed a high-fat diet. The increased insulin sensitivity observed in this study is attributed to the tempol-induced reduction in obesity. Numerous studies in rodents and humans have correlated increased insulin sensitivity to reductions in fat content. Comparative analysis showed that intestine-specific FXR null mice exhibited a reduced level of diet-induced obesity even when fed a high-fat diet. Importantly, relative to the mode of action of tempol, is the fact that this study also showed that tempol administration to the intestine-specific FXR null mice did not further decrease weight gain. This demonstrates that the effects observed as a result of tempol ingestion are due to gut-specific responses to the drug not due to effects in other tissues as a result of the absorption of tempol from the gut.

The take home from this study is that compounds like tempol may find utility in the ongoing battle against obesity in humans. It should be pointed out that there is still much work to be done to be able to fully (or even partially) comprehend how we can manipulate the gut microbiome and what types of manipulations should be made. In this study there was a distinct benefit to reducing the level of the genus Lactobacillus in effecting a positive change in obesity. However, other studies have shown benefits to Lactobacillus. The ingestion of Lactobacillus by laboratory rodents has been associated with reduced anxiety and stress. In addition, most probiotics sold at health food stores are predominantly composed of strains of Lactobacillus.

Tuesday, September 10, 2013


Metformin is a hypoglycemia-inducing drug of the biguanide family that has been used to treat the hyperglycemia associated with type 2 diabetes for over 50 years. Indeed, metformin is the most frequently prescribed diabetes treatment drug.

For more information on the effects of metformin go the the Diabetes page of

Metformin exerts several effects in several cell types but with respect to overall glucose homeostasis its effects on hepatic metabolism include an induction of glucose metabolism (glycolysis) and repression of glucose synthesis (gluconeogenesis). Combined, these two effects significantly contribute to the promotion of an increase in whole body insulin sensitivity. Over the years studies with metformin have shown that this drug mimics some of the benefits of calorie restriction, such as improved physical performance, increased insulin sensitivity, and reduced low-density lipoprotein (LDL) and cholesterol levels without a decrease in caloric intake. Examination of gene expression profiles demonstrated that metformin induces a gene expression profile highly similar to that induced by calorie restriction. At a molecular level, one of the most important effects of metformin is an increase in AMP-activated protein kinase (AMPK) activity. Increased AMPK activity is associated with increased antioxidant protection, resulting in reductions in both oxidative damage accumulation and chronic inflammation, both of which are hallmarks of aging processes. Despite all these important observations there is still controversy regarding whether or not metformin is involved in lifespan extension.

A recent study published in the journal Nature Communications indicates that long-term metformin administration in laboratory animals does indeed lead to increases in lifespan:

In this study adult mice were treated with two different doses of metformin continuously until the mice died naturally. The results demonstrated two critical facts. The first is that too much metformin (the mice treated with the higher of the two doses) was toxic and led to a shortened lifespan compared to control untreated mice. The other observation was that mice given the lower dose of metformin exhibited an extension of their lifespan by 5-6% over that of control mice. Additionally significant findings were that when these mice died (at around 115 weeks of age) they showed no obvious pathology that would account for why they died compared to untreated control mice. Another important finding was that the low dose metformin treated mice were healthier than the untreated mice in the measure of body mass. As humans and animals age there is a progressive change in body mass, and in animal studies the ability to maintain a youthful body mass is associated with healthier parameters. In this study the metformin treated mice maintained a healthy weight even at 124 weeks of age even though they actually ate more calories than untreated mice. This indicated that metformin treatment altered the metabolic profiles of the mice. Indeed, metformin treatment was associated with increased fat oxidation rates and reduced lipid synthesis even though there was no significant increase in the activity level of the treated mice. Similar examinations in short-term metformin studies have shown that the drug partially inhibits mitochondrial functions but this study indicates that long-term there is an adaptation to beneficial metformin effects. Detailed molecular studies in these metformin treated mice showed that the drug inhibited inflammation and preserved mitochondrial functions by inducing a pattern of gene expression that was very similar to that observed in mice on a calorie restricted diet.

The TAKE HOME from this study is that chronic metformin treatment, in type 2 diabetics, may actually have unforeseen benefits unrelated to the prescribed benefit of reduced serum glucose. However, it should be noted although the dose associated with the beneficial effects in the mice was well tolerated, the dose used was an order of magnitude higher than that conventionally used in human patients. Therefore, it is clear that although promising, further studies on the dose and length of metformin treatment in humans is necessary to fully ascertain the effects and potential benefits of chronic exposure to biguanides in health and aging in humans.

Sunday, September 8, 2013


Bariatric surgery is an extreme procedure involving gastric bypass as a means of treatment for morbid obesity and obesity. There are many different types of gastric bypass with the Roux-en-Y procedure (RYGB) being one of the more common. The RYGB procedure involves surgically reducing the size of the stomach to a small pouch by stapling off a section of the stomach then attaching this pouch directly to the small intestine, bypassing most of the rest of the stomach and the upper part of the small intestine. RYGB has been shown to induce substantial and sustained weight loss. An interesting and unexpected finding in patients who underwent the RYGB is that the observed improvement in overall glucose homeostasis occurs early after the RYGB procedure, before any appreciable weight loss, and as a result these patients are often able to discontinue their antidiabetic medications before hospital discharge. However, the means by which the RYGB effected these changes in glucose homeostasis have not been determined.
In a recent study published in the prestigious journal Science it has been determined that a major metabolic consequence of the RYGB procedure is an increase in glucose utilization by the intestines resulting in increased disposal of glucose from the blood, thereby, rapidly reducing the hyperglycemia of type 2 diabetes.

The authors of this study hypothesized that that the beneficial effect of RYGB on glucose homeostasis might likely be due to the fact that the jejunum (the middle section of the small intestine), which normally does not see undigested food, now has an altered metabolism necessary to meet the increased bioenergetic demands of tissue growth and maintenance, possibly in response to exposure of this section of the intestine to undigested nutrients.
These studies were carried out in rats and the initial work centered on a comparative analysis of the metabolic profiles in sham operated jejunal tissue versus RYGB jejunal tissue. The results of metabolomic profiling showed increased concentrations of intermediates of the oxidative phase of the pentose phosphate pathway, increased intermediates of the pyrimidine and purine biosynthetic path-ways, increased lactate production was increased, there was increased serine biosynthesis and hexosamine biosynthetic activity (the HBP), two metabolic pathways that branch off from glycolysis. In addition, the glutamine/glutamate pathway was enhanced as was the metabolism of several other amino acids. The observed changes in metabolic profiles following the RYGB indicates that glycolysis may be up-regulated in in order to shunt glucose carbons into metabolic pathways that support the accumulation of biomass necessary for cellular growth and proliferation. Metabolomic changes in the RYGB rats were also mirrored by examination of transcriptomic profiles that demonstrated increased expression of key glycolytic enzymes.

The effectiveness of RYGB, not only at the level of weight loss, but in the resolution of hyperglycemia and insulin resistance in type 2 diabetes attests to the important role of the gastrointestinal tract in overall glucose homeostasis. Most previous studies suggested that these effects of RYGB were due to changes gastrointestinal hormones that control glucose homeostasis such as glucagon-like peptide-1 (GLP-1). Other animal studies have also demonstrated that changes in intestinal gluconeogenesis following a different type of gastric bypass resulted in reduced hepatic gluconeogenesis. However, studies in humans who underwent the RYGB procedure did not show appreciable induction of intestinal gluconeogenesis so there is some controversy as to the role of intestinal gluconeogenesis in the efficacy of gastric bypass in ameliorating the hyperglycemia of type 2 diabetes.

The TAKE HOME from this study first confirms the physiological benefits of the use of the RYGB procedure in the treatment of obesity and type 2 diabetes. Specifically, this study demonstrated that changes in overall metabolism in the jejunal limb of the bypass structure may be primarily responsible for improved glucose homeostasis following RYGB. The resulting reprogrammed intestinal glucose metabolism leads to the intestine becoming a major organ for glucose disposal which in turn contributes to the overall improvement in glycemic control following RYGB and the associated improvement in the hyperglycemia associated with type 2 diabetes.

Saturday, September 7, 2013


More and more research is demonstrating the beneficial roles played by the bacteria that reside within our intestines in the control, regulation, and modulation of normal physiological status and that disruption in the ratios of certain types of bacteria are associated with disease states such as obesity and type 2 diabetes, and the associated increase in intestinal inflammation and gut barrier disruption this causes. Indeed, I have written about this area of research in the pages of this blog earlier this year:

As always you can read more about the correlation between obesity and gut bacteria in the Obesity page of

A recent paper just published in the prestigious journal Science demonstrates that administration of bacteria from thin human feces prevents obesity in mice even when they are fed a high-fat diet.

This most elegant study study compared the effects of the administration of uncultured (feces) or culturable bacteria from twins that were both obese or who were both lean, to mice. These types of studies are designed to ascertain precisely what types of bacteria, and especially how these bacteria, effect the differences in metabolism observed in lean versus obese individuals. Previous work, for example, has shown that transplanting fecal bacteria from healthy donors to recipients with metabolic syndrome (MetS) results in the amelioration of insulin-resistance. In this current study, the bacteria (feces) from obese twins resulted in significantly greater increases in body mass and adiposity (fat) in the mice than did the bacteria (feces) from lean twins. These changes in overall metabolism in the mice were correlated to differences in the metabolic profiles of the bacteria. Bacteria in the gut metabolize (ferment) undigested fiber into short-chain fatty acids (SCFA) which exert important metabolic effects on host tissue such as the intestine. These SCFA were increased in the mice fed bacteria from lean twins relative to those fed bacteria from obese twins. The mice fed obese bacteria also showed higher levels of amino acid metabolism including essential and branched-chain amino acids (BCAA). This pattern of amino acid metabolism by the obese bacteria in these mice is very similar to elevations seen in BCAA and related amino acids observed in obese and insulin-resistant versus lean and insulin-sensitive humans. In addition, bacterial metabolism of bile acids into molecules that down-regulated host FXR receptorsignaling was significantly higher with lean bacteria than with the obese bacteria. The significance of this latter observation relates to the role of FXR-regulated bile acid synthesis and how this relates to serum cholesterol levels since bile acid synthesis is the major means for excretion of cholesterol. Activation of intestinal FXR induces expression of intestinal fibroblast growth factor 15 (FGF15) which is then secreted to the portal circulation where it binds to, and activates the liver fibroblast growth factor receptor 4 (FGFR4). This activation then results in inhibited expression of the rate-limiting enzyme in bile acid biosynthesis, cholesterol 7-a-hydroxylase (CYP7A1) resulting in lower rates of bile acid synthesis. Therefore, the observation that mice fed lean bacteria have reduced levels of activated FXR in the gut can be directly correlated to increased bile acid synthesis and increased disposition of cholesterol. Indeed, studies have shown that over-expression of CYP7A1 can prevent diet-induced obesity and insulin resistance. An additional finding in this study was that when mice fed lean twin bacteria were housed with mice fed obese twin bacteria the latter mice had reduced fat mass and adiposity accumulation compared to mice fed obese twin bacteria that were not co-housed with lean bacteria fed mice.

TAKE HOME from this study: it could be argued that an easy (but potentially distasteful, pun intended) solution to obesity is just to consume a small amount of feces from skinny humans. Given that most, if not all, of the bacteria in our guts are anaerobic, due to the lack of oxygen in the gut, it is difficult to culture the beneficial strains so that they can be delivered in the diet. In addition, there are 500 to 1000 different species of bacteria in the gut making it highly laborious to separate and culture each and every individual strain. However, in spite of these limitations it is clear that very soon there will be available methods to treat obese and type 2 diabetic individuals with cocktails of beneficial gut microbiota. Look for this to be the next HUGE market in the alternative medical and dietary supplement market. Already, numerous yogurt manufacturers are making claims to the health benefits of the probiotic cultures in their yogurt.

Sunday, August 18, 2013


Until recently fats were considered mere sources of energy and as components of biological membranes. However, research over the past 10-15 years has demonstrated a widely diverse array of biological activities associated with fatty acids and fatty acid derivatives as well as other lipid compounds. Bioactive lipids span the gamut of structural entities from simple saturated fatty acids to complex molecules such as those derived from various omega-3 and omega-6 fatty acids and those derived from sphingosine. All bioactive lipids exert their effects through binding to specific receptors, many of which are members of the G-protein coupled receptor (GPCR) family and also many of which have just recently been characterized. Bioactive lipids play important roles in energy homeostasis, cell proliferation, metabolic homeostasis, and regulation of inflammatory processes.

Oleoylethanolamide (OEA) is very important and potent member of the bioactive lipid family. This molecule is a member of the fatty-acid ethanolamide family that includes palmitoylethanolamide (PEA) and N-arachidonoylethanolamide (anandamide). Anandamide was identified as an endogenous ligand (endocannabinoid) for the cannabinoid receptors.

For more details on anandamide and other endocannabinoid functions go to the Endocannabinoids page of my website.

OEA is produced by mucosal cells in the proximal small intestine from dietary oleic acid. Synthesis of OEA occurs on demand within the membrane of the cell. OEA has been shown to activate the fatty acid-sensing GPCR identified as GPR119 as well as the non-selective gated cation channel TRPV1 (transient receptor potential vanilloid 1), and to interact with intestinal fatty acid translocase (FAT/CD36) for uptake from the gut. Although the evidence is strong indicating that OEA may be the endogenous ligand for GPR119, its' interaction with FAT/CD36 is required for the satiety response elicited by this bioactive lipid. The demonstration that OEA is the most active endogenous ligand for GPR119 is of particular interest since previous work has demonstrated that OEA, when administered to laboratory animals, causes a significant reduction in food intake and body weight gain. These effects of OEA are the result of the activation of the nuclear receptor PPARα resulting in increased expression of fatty acid translocase and modification of feeding behavior and motor activity.

For more details on oleoylethanolamide (OEA) go to the Bioactive Lipids page of my web site.

A recent paper just e-published in the journal Science demonstrates that OEA plays a critical role in the responses of the limbic system of the brain to the neurotransmitter, dopamine. Dopamine is known to exert a wide range of responses within the CNS and is of particular importance in the establishment of reward circuitry as relates to feeding behaviors and drug seeking behaviors.

Several studies in humans and in laboratory animals have shown a link between obesity, particularly associated with a high-fat diet, and a decrease in dopamine release within the brain. This decrease in dopamine release is suspected to exacerbate obesity by provoking compensatory overfeeding as one way to restore reward sensitivity. Precisely how a high fat diet exerts a negative effect on CNS dopamine release is not yet fully understood. What is now known as a result of the finding in this recent Science paper is that administration of OEA to rodents is sufficient to re-establish the release of dopamine in response to a high-fat diet. The OEA (or vehicle control) in these experiments was administered intraduodenally and then the effects of feeding either low-fat or high-fat diets on dopamine release was examined. As a starting point, dopamine release was assayed in mice fed the high-fat diet or the low-fat diet. The high-fat diet mice failed to elicit the typical calorie-dependent dopamine release. In the low-fat diet fed animals consumption of a high calorie bolus of food elicited a strong dopamine release that was not affected either way by prior administration of OEA. On the other hand the high-fat diet fed animals showed a level of dopamine release that was similar to that of the low-fat diet fed animals ONLY after OEA administration. In addition, OEA administration was shown to produce an anorectic effect (lack of desire for food intake) in both low-fat and high-fat diet animals fed a bolus of high-calorie food. However, OEA produced these anorectic effects during oral low-fat intake in the low-fat diet fed animals while stimulating low-fat intake in the high-fat diet animals. Another consistent result from these experiments was that OEA administration resulted in decreased weight gain and a desire for fat intake in the high-fat diet fed mice.

The take home from this study is that there is great potential for the use of compounds, such as OEA, to re-establish the gut-lipid signaling pathways that beneficially regulate dopamine-mediated reward behaviors related to food intake and appetite. Of particular interest to human diets is the fact that extra-virgin olive oil has a high concentration of oleic acid which if the precursor to the gut synthesis of OEA. Another oil high in oleic acid, but not as readily available as a food-grade oil, is argan oil. Argan oil is better known for its use in cosmetics However, one can find this highly beneficial oil in food quality on the internet in bottled form as well as in gel cap form.

If you start spreading the word about the health benefits of argan oil I would appreciate you mentioning that you heard it from Dr. Michael W. King, and NOT Dr. Oz!!!

Tuesday, August 6, 2013


I have posted several times here about the consequences of a mothers dietary intake and weight status on the future health of her unborn child. There are numerous reports in the literature that clearly point to the fact that if a mother consumes a diet in excess of her caloric needs, her unborn child will have a significantly altered pattern of neurotransmitter expression related to the control of appetite and feeding behavior. In other word,s the child/children of an overweight/obese mother will have a strong innate desire to consume a diet of excess caloric need, will have a significant increase in the likelihood of becoming obese, and suffer the consequences of that inappropriate diet such as type 2 diabetes, hypertension, and cardiovascular disease. This very fact is resulting in an uncontrolled explosion in the obese population in the US and other industrialized nations who consume a typical "Western-style" diet particularly among adolescent children. 

A new report just published in the journal, Biology of Reproduction, presents further evidence linking maternal diabetes and epigenetic alterations in offspring due to changed in the expression of imprinted genes in oocytes (eggs).

Maternal Diabetes Causes Alterations of DNA Methylation Statuses of Some Imprinted Genes in Murine Oocytes

This study examined the effects/consequences of maternal diabetes on the methylation status of several imprinted genes during embryonic development in laboratory mice. Imprinted genes are a class of genes whose expression pattern is dictated by the parental origin and this expression pattern is controlled by the methylation status of the imprinted gene, or in some cases to the alelle-specific state of histone methylation or acetylation. The first imprinted gene identified was the insulin-like growth factor 2 (IGF-2) gene. At least 80 genes are known to be imprinted in the human genome. Defects in the proper expression of numerous imprinted loci result in potentially devastating disorders.

You can read more about some of the most common imprinting diseases in the Diseases Associated with Genomic Imprinting page on

Many previous studies demonstrated that oocytes exposed to diabetic conditions during folliculogenesis exhibit negative effects related to maturation and developmental potential. Mitochondrial function, glucose metabolism pathways, and communications between cumulus cells and the oocyte are all changed in follicles of maternal diabetic mice.

In non-imprinted regions of the chromosomes, the parental epigenetic marks are erased in the germ cells only to be newly established in a parental-specific manner. Once the parental-specific epigenetic marks are established, they are maintained following fertilization. In contrast, imprinted genes exhibit what are referred to as differentially methylated regions (DMRs) and these DMRs escape the genome-wide demethylation that takes place during the earliest cleavage events of embryonic development. In addition, these DMRs escape the global de novo methylation that normally occurs when the embryo undergoes implantation. Two distinct types of DMRs have been found: those that are formed following fertilization and those that are formed in the germ cells and maintained throughout development. The latter DMRs are associated with chromosomal regions termed imprinting control centers, ICRs. Therefore, defects in the proper regulation of these DMRs can lead to profound consequences for the offspring resulting from fertilization of epigenetically altered oocytes and/or sperm.

This study examined the effects of maternal diabetes on the methylation status of two maternal genes Peg3 (a zinc-finger transcription factor originally identified as "paternally expressed gene 3") and Snrpn (small nuclear ribonucleoprotein polypeptide N). What this research discovered is that maternal diabetes altered the methylation status of Peg3 in a time-dependent manner. In othre words the changes become more pronounced the longer the female was diabetic. However, in this study the methylation status of Peg3 was not altered in the oocytes of female offspring.

So there is a bad-news good-news side to this research. The bad-news is that maternal diabetes has a negative effect on oocyte maturation and epigenetic status which results in negative consequences to oocyte maturation which can, in turn, result in negative developmental outcomes for offspring but the good-news is that the study did not find that the altered maternal oocyte epigenome was "transferred" to the female offspring oocyte epigenome.

Tuesday, July 16, 2013


Several hormones and bioactive peptides are secreted from specialized cells within the gastrointestinal tract. The stomach and small intestines are the major sites for the secretion of these proteins. Several of these factors, following release to the blood stream, have been known for some time to exert effects within the central nervous system that affect our desire to eat and also the level of satiety experienced following the consumption of food. These gut appetite regulating proteins are of two types: those that inhibit the desire for food are called anorexigenic factors, while those that stimulate our desire for food are called orexigenic. The majority of gut proteins that exert effects on appetite and satiety are anorexigenic, whereas, there is but a single gut peptide (ghrelin) that acts in an orexigenic manner in the brain. The anorexigenic gut peptides include protein tyrosine tyrosine (PYY), pancreatic polypeptide (PP), cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), oxyntomodulin (OXM), and apolipoprotein A-IV (apoA-IV).

For more details on the role of gut peptides in the regulation of appetite and feeding behaviors visit the Gut-Brain Interrelationships page of my web site.

A recent paper just e-published in the journal Obesity demonstrates that administration of two of these anorexigenic gut hormones PYY and PP in combination results in reduced feeding behavior in an additive manner in laboratory mice paving the way for their potential use in the treatment of obesity in humans.

Both PYY (the biologically active circulating form of PYY is called PYY3-36 because it contains amino acids 3-36 of the primary translation product of the PYY gene) and PP have previously been shown to potently inhibit food intake both animals and humans. The results of this study demonstrate that addition of both of these gut peptides simultaneously results in an inhibition of feeding behavior that is additive. In other words the repression of appetite in lab animals was significantly higher in mice receiving both hormones compared to mice receiving either hormone alone. These effects were exerted via two distinct neuronal pathways in the hypothalamus. The hypothalamus is a region of the brain critically involved in the integration of metabolic demands of the body with the stimulation or repression of appetite and feeding behaviors.

The take home from this study is that there is great potential for the use of combination therapies such as co-administration of PYY and PP agonists in the treatment of obesity. The advantages of dual administration therapies is that the doses of either compound could be reduced to lessen any potential for untoward side-effects, while still maintaining potent regulation of appetite and weight gain.