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Showing posts from June, 2010

Exercise and blood glucose levels: Insulin and glucose responses to exercise

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The notion that exercise reduces blood glucose levels is widespread. That notion is largely incorrect. Exercise appears to have a positive effect on insulin sensitivity in the long term, but also increases blood glucose levels in the short term. That is, exercise, while it is happening, leads to an increase in circulating blood glucose. In normoglycemic individuals, that increase is fairly small compared to the increase caused by consumption of carbohydrate-rich foods, particularly foods rich in refined carbohydrates and sugars. The figure below, from the excellent book by Wilmore and colleagues (2007) , shows the variation of blood insulin and glucose in response to an endurance exercise session. The exercise session’s intensity was at 65 to 70 percent of the individuals’ maximal capacity (i.e., their VO 2 max). The session lasted 180 minutes, or 3 hours. The full reference to the book by Wilmore and colleagues is at the end of this post. As you can see, blood insulin levels decrease

Nutrition and Breast Cancer

Thanks to recent research in nutrition, dietary strategies are helping many more women survive breast cancer and go on to live long, healthy lives.  Often enough, evidence reveals these strategies may work by influencing inflammation, the immune system, and insulin responsiveness. However, there is no nutritional therapy that is yet "proven" to treat cancer directly or increase survival. According to large trials of diet and breast cancer such as the Women's Healthy Eating and Living (WHEL) randomized trial and the Women's Intervention Nutrition Study (WINS) trial, as well as small intervention studies, a lower calorie diet leading to controlled weight reduced mortality.  The reason - being overweight or obese appears to increase mortality because of higher risk of metastasis. Crash dieting is not the key, only healthy weight loss and patients should consult a nutritionist for planning meals.  Patients should note that diets too low in calories can lead to loss of mus

Compensatory adaptation as a unifying concept: Understanding how we respond to diet and lifestyle changes

Trying to understand each body response to each diet and lifestyle change, individually, is certainly a losing battle. It is a bit like the various attempts to classify organisms that occurred prior to solid knowledge about common descent. Darwin’s theory of evolution is a theory of common descent that makes classification of organisms a much easier and logical task. Compensatory adaptation (CA) is a broad theoretical framework that hopefully can help us better understand responses to diet and lifestyle changes. CA is a very broad idea, and it has applications at many levels. I have discussed CA in the context of human behavior in general (Kock, 2002), and human behavior toward communication technologies (Kock, 2001; 2005; 2007). Full references and links are at the end of this post. CA is all about time-dependent adaptation in response to stimuli facing an organism. The stimuli may be in the form of obstacles. From a general human behavior perspective, CA seems to be at the source of

What about some offal? Boiled tripes in tomato sauce

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Tripe dishes are made with the stomach of various ruminants. The most common type of tripe is beef tripe from cattle. Like many predators, our Paleolithic ancestors probably ate plenty of offal, likely including tripe. They certainly did not eat only muscle meat. It would have been a big waste to eat only muscle meat, particularly because animal organs and other non-muscle parts are very rich in vitamins and minerals. The taste for tripe is an acquired one. Many national cuisines have traditional tripe dishes, including the French, Chinese, Portuguese, and Mexican cuisines – to name only a few. The tripe dish shown in the photo below was prepared following a simple recipe. Click on the photo to enlarge it. Here is the recipe: - Cut up about 2 lbs of tripe into rectangular strips. I suggest rectangles of about 5 by 1 inches. - Boil the tripe strips in low heat for 5 hours. - Drain the boiled tripe strips, and place them in a frying or sauce pan. You may use the same pan you used for boi

Pretty faces are average faces: Genetic diversity and health

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Many people think that the prettiest faces are those with very unique features. Generally that is not true. Pretty faces are average faces. And that is not only because they are symmetrical, even though symmetry is an attractive facial trait. Average faces are very attractive, which is counterintuitive but makes sense in light of evolution and genetics. The faces in the figure below (click to enlarge) are from a presentation I gave at the University of Houston in 2008. The PowerPoint slides file for the presentation is available here . The photos were taken from the German web site Beautycheck.de . This site summarizes a lot of very interesting research on facial attractiveness. The face on the right is a composite of the two faces on the left. It simulates what would happen if you were to morph the features of the two faces on the left into the face on the right. That is, the face on the right is the result of an “averaging” of the two faces on the left. If you show these photos to a

Soccer as play and exercise: Resistance and endurance training at the same time

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Many sports combine three key elements that make them excellent fitness choices: play, resistance exercise, and endurance exercise; all at the same time. Soccer is one of those sports. Its popularity is growing, even in the US! The 2010 FIFA World Cup , currently under way in South Africa, is a testament to that. It helps that the US team qualified and did well in its first game against England. Pelé is almost 70 years old in the photo below, from Wikipedia. He is widely regarded as the greatest soccer player of all time. But not by Argentineans, who will tell you that Pelé is probably the second greatest soccer player of all time, after Maradona . Even though Brazil is not a monarchy, Pelé is known there as simply “The King”. How serious are Brazilians about this? Well, consider this. Fernando Henrique Cardoso was one of the most popular presidents of Brazil. He was very smart; he appointed Pelé to his cabinet. But when Cardoso had a disagreement with Pelé he was broadly chastised i

10 Steps for Patients with Cholesterol-Induced Cardiomyopathy

Cardiomyopathy is characterized by a weakened, enlarged or inflamed cardiac muscle. The disease may be in primary stages (asymptomatic) or secondary stages (symptoms such as shortness of breath, fatigue, cough, orthopnea, nocturnal dyspnea or edema) with main types being dilates, hypertrophic, restrictive, or arrhythmogenic (1). Treatment may include drugs such as ACE inhibitors and beta blockers, implantable cardioverter-defibrillators, cardiac resynchronization therapy, or heart transplant (1). Factors leading to cardiomyopathy may include alcohol consumption, smoking, obesity, sedentary lifestyle, smoking and high-sodium diet (1). Hypercholesterolemia can lead to fatty streaks in blood vessels that result in decreased flow of blood through arteries. The advent of hypercholesterolemia may be directly related to cardiomyopathy as it’s well established as a risk factor in inducing systolic and diastolic dysfunction (2). Statins such as Lovastatin are commonly prescribed because of effi

Fructose in fruits may be good for you, especially if you are low in glycogen

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Excessive dietary fructose has been shown to cause an unhealthy elevation in serum triglycerides. This and other related factors are hypothesized to have a causative effect on the onset of the metabolic syndrome. Since fructose is found in fruits (see table below, from Wikipedia; click to enlarge), there has been some concern that eating fruit may cause the metabolic syndrome. Vegetables also have fructose. Sweet onions, for example, have more free fructose than peaches, on a gram-adjusted basis. Sweet potatoes have more sucrose than grapes (but much less overall sugar), and sucrose is a disaccharide derived from glucose and fructose. Sucrose is broken down to fructose and glucose in the human digestive tract. Dr. Robert Lustig has given a presentation indicting fructose as the main cause of the metabolic syndrome, obesity, and related diseases. Yet, even he pointed out that the fructose in fruits is pretty harmless. This is backed up by empirical research . The problem is over-consump

Cortisol, stress, excessive gluconeogenesis, and visceral fat accumulation

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Cortisol is a hormone that plays several very important roles in the human body . Many of these are health-promoting, under the right circumstances. Others can be disease-promoting, especially if cortisol levels are chronically elevated. Among the disease-promoting effects of chronically elevated blood cortisol levels are that of excessive gluconeogenesis, causing high blood glucose levels even while a person is fasting. This also causes muscle wasting, as muscle tissue is used to elevate blood glucose levels. Cortisol also seems to transfer body fat from subcutaneous to visceral areas. Presumably cortisol promotes visceral fat accumulation to facilitate the mobilization of that fat in stressful “fight-or-flight” situations. Visceral fat is much easier to mobilize than subcutaneous fat, because visceral fat deposits are located in areas where vascularization is higher, and are closer to the portal vein. The problem is that modern humans often experience stress without the violent musc

Niacin turbocharges the growth hormone response to anaerobic exercise: A delayed effect

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Niacin is also known as vitamin B3, or nicotinic acid. It is an essential vitamin whose deficiency leads to pellagra. In large doses of 1 to 3 g per day it has several effects on blood lipids, including an increase in HDL cholesterol and a marked decreased in fasting triglycerides. Niacin is also a powerful antioxidant. Among niacin’s other effects, when taken in large doses of 1 to 3 g per day, is an acute elevation in growth hormone secretion . This is a delayed effect, frequently occurring 3 to 5 hours after taking niacin. This effect is independent of exercise. It is important to note that large doses of 1 to 3 g of niacin are completely unnatural, and cannot be achieved by eating foods rich in niacin. For example, one would have to eat a toxic amount of beef liver (e.g., 15 lbs) to get even close to 1 g of niacin. Beef liver is one of the richest natural sources of niacin. Unless we find out something completely unexpected about the diet of our Paleolithic ancestors in the future

Low muscle mass linked to diabetes

Being overweight is a risk factor for type 2 diabetes; however, a new study shows losing weight alone may not be enough to reduce risk of type 2 diabetes in people with low muscle mass and strength, particularly if they are over the age of 60. These are the findings of new research from Dr. Preethi Srikanthan of University of California, Los Angeles, and colleagues who performed a cross-sectional analysis of 14,528 people from National Health and Nutrition Examination Survey III. Dr. Srikanthan and colleagues concluded that age-related muscle loss, or sarcopenia, was associated with greater insulin resistance; and, sarcopenia, independent of obesity, may be an early predictor of diabetes. This association of sarcopenia and insulin resistance was strongest in those who were 60 years and older, the researchers warn. Apart from these poor health outcomes, sarcopenia in older adults is also clearly associated with other health outcomes such as increased risk of falls, hip fractures, bone l

Briefly on Detoxification Systems

Every day we are exposed to toxins, or xenobiotics, that are found in our food, water and environment. The body also makes toxins within itself. These all must be either stored such as in muscle or fat or they are  detoxified and eliminated via the feces or urine. The body's main detoxification organ is the liver, but can also happen in the intestine and other organs. The detoxification systems handle a wide range of compounds mainly by two steps: phase I and phase II detoxification.  Phase I detoxification is a reaction that entails functionalization of the compound, breaking it down. The major P450 enzymes are generally involved in phase I detoxification. Most major drugs and exogenous toxins are metabolized this way. At times the product of phase I detoxification can be more harmful than the original product.   Phase II detoxification is a second reaction that generally follows phase I detoxification. It entails transforming a phase I reactant through conjugation (typically to a

Growth hormone secretion drops with age, but not exactly in the way you would expect

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Many people assume that growth hormone secretion drops with age in a somewhat linear fashion, as implied by this diagram . This assumption probably stems from attempts to model growth hormone variations with linear regression algorithms. This assumption is wrong. Actual plots of growth hormone secretion patterns, with age on the horizontal axes, tell a different story. See, for example, the graphs below, from professionalmuscle.com. They match the graphs one sees in empirical academic papers. The graphs below (click to enlarge) are particularly good at highlighting some interesting patterns of variation. On the left side, bar charts show secretion patterns grouped by age ranges during a 24 h period (at the top), during wake time (at the middle), and during sleep (at the bottom). On the right side is the actual data used to build the bar charts. As you can see from the graphs on the right side, the drop in growth hormone secretion follows a pattern that looks a lot more like an exponent

Cortisol response to stress is much more elevated with ingestion of glucose than with protein or fat

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Cortisol is a hormone that does a number of different things; a jack of all trades among hormones, so to speak. It tells the liver to produce glucose, preventing hypoglycemia. It also tells the liver to synthesize glycogen, which is in some ways the opposite of producing glucose. It tells the stomach to secret gastric acid. It is an anti-diuretic hormone. It suppresses the immune system, which is why it is frequently used to reduce inflammation, and treat allergies and various autoimmune diseases. It jump-starts an increase in free fatty acids in circulation, thus helping provide an important source of energy for endurance exercise. Cortisol, together with epinephrine (a.k.a. adrenaline), even contributes to the creation of surprise-induced memories. It is because of this action of cortisol that Americans reading this post, especially those who lived in the East Coast in 2001, remember vividly where they were, what they were doing, and who they were with, when they first heard about th