Thursday, July 31, 2008

Nutrition & Metabolism | Full text | Ketogenic diets and physical performance

Nutrition & Metabolism | Full text | Ketogenic diets and physical performance

Abstract

Impaired physical performance is a common but not obligate result of a low carbohydrate diet. Lessons from traditional Inuit culture indicate that time for adaptation, optimized sodium and potassium nutriture, and constraint of protein to 15–25 % of daily energy expenditure allow unimpaired endurance performance despite nutritional ketosis.
Introduction

In the opinion of most physicians and nutrition scientists, carbohydrate must constitute a major component of one's daily energy intake if optimum physical performance is to be maintained [1]. This consensus view is based upon a long list of published studies performed over the last century that links muscle glycogen stores to high intensity exercise. It has also been reinforced by the clinical experience of many physicians, whose patients following low carbohydrate formula or food diets frequently complain of lightheadedness, weakness, and ease of fatigue.

During the time that this consensus view of the necessity of carbohydrate for vigorous exercise was forming, the last pure hunting cultures among the peoples of North America finally lost out in competition with expanding European cultural influences. Between 1850 and 1930, the routine consumption of carbohydrates spread north from the U.S. Plains States through central Canada, where the indigenous peoples had heretofore made at most seasonal use of this nutrient class. However the last of these groups to practice their traditional diet, the Inuit people of the Canadian and Alaskan Arctic regions, were luckily observed by modern scientists before their traditional dietary practices were substantially altered. The reports of these early scientists imply that the Inuit people were physically unhampered despite consuming a diet that was essentially free of identifiable carbohydrate.

Given this juxtaposition of clinical research results favoring carbohydrate against observed functional well-being in traditional cultures consuming none, it is an interesting challenge to understand how these opposing perspectives can be explained. This paper will review the observations of early explorer scientists among the Inuit, track the controversy that they stimulated among nutritionists in the last century, and utilize some of the forgotten lessons from the Inuit culture to explain how well-being and physical performance can be maintained in the absence of significant dietary carbohydrate.
The origins of carbohydrate supremacy

Until the development of agriculture over last few millennia, our human ancestors' consumption of dietary carbohydrate was opportunistic. As some groups adapted to hunting and fishing for their sustenance, they were able to move into temperate and then arctic regions, where limited access to wild grain, nuts, and fruit dictated sustained dependence upon fat and protein as primary sources of dietary energy.

With the development of agriculture came the ability to grow and store grain, allowing societies to remain in a stable physical location, build permanent dwellings, and potentially stimulating the development of written language (those early stone tablets would have been difficult to transport from camp to camp on a dog sled). Starting from locations in the Middle East and Asia, cultures based upon agricultural wheat and rice spread over 5 millennia to dominate Europe, Africa, and the Americas.

With its ability to support a non-nomadic life style, greater population density, and permanent communities; there were clear advantages of agriculture-based societies over those based upon hunting and fishing, particularly as agricultural communities built the infrastructure to support trade and transport. Given its success in this competition of cultures (and by implication, the competition of their diets), it is an easy assumption that a grain-based diet is functionally superior to one based upon the meat and fish (fat and protein) of the hunting societies that they superseded.

As the science of nutrition developed in the early 20th Century, numerous comparative studies were undertaken to assess differences between diets. Although there were some advocates of low carbohydrate diets (eg, the Banting diet of the 19th Century, promoted for weight loss and diabetes control), the prevailing premise for these studies was that carbohydrate was a necessary nutrient for optimum human health and function. Among studies confirming this view, a classic was the 1939 study by two Danish scientists, Christensen and Hansen [2]. They did a crossover study of low carbohydrate, moderate carbohydrate, and high carbohydrate diets, each lasting one week. At the end of each diet, the subjects' endurance time to exhaustion on a stationary bicycle was assessed. Compared to the mean endurance time on the low carb diet of 81 minutes, the subjects were able to ride for 206 minutes after the high carb diet.

During the Second World War, another oft-cited study was performed, this time examining the practicality of pemmican (a mixture of dried meat and fat) as a light-weight emergency ration for soldiers. This experiment by Kark et al [3] involved abruptly switching soldiers in winter training in the Canadian Arctic from standard carbohydrate-containing rations to pemmican. This study only lasted 3 days, as the soldiers rapidly became unable to complete their assigned tasks, which included pulling loaded sleds 25-miles per day through deep snow.

With the resurgence of biomedical science in the 1960's came development of the percutaneous needle biopsy, facilitating assessment of intra-muscular fuel stores and metabolism. This led to the concept of muscle glycogen as the limiting fuel for high intensity exercise [4] and to the nutritional strategy of carbohydrate loading [5]. The clear consensus that developed from this research was that fat had limited utility as a fuel for vigorous exercise, and that humans are physically impaired if given a low carbohydrate diet.
The hunter's counterpoint – practical observations on ketogenic diets

Although high-carbohydrate diets might be more effective in short-term tests of high-intensity exercise, there are multiple clues in the published literature that the debilitating effects of ketogenic diets are overstated. Not only is there the demographic evidence that whole populations of people lived for millennia as hunters, but there are many reports of Europeans crossing over to live within the cultures of these hunting societies without apparent impediment.

One of the earliest documented demonstrations of physical stamina during a ketogenic diet was the Schwatka 1878–80 expedition in search of the lost Royal Navy Franklin expedition. The Schwatka expedition, sponsored by the New York Herald and the American Geographical Society, departed from the west coast of Hudson's Bay in April of 1879 with 4 Caucasians, 3 families of Inuits, and 3 heavily laden dog sleds. Totaling 18 people, they started out with a month's supply of food (mostly walrus blubber) and a prodigious supply of ammunition for their hunting rifles. After covering over 3000 miles on foot over ice, snow and tundra, all 18 members of the original party plus their 44 dogs returned to Hudson's Bay in March of 1880. Once their initial provisions were depleted, the expedition's only source of additional food was hunting and fishing, as there were no other sources of supply along their route.

The leader of this expedition, Lt. Frederick Schwatka, was a graduate of both West Point and Bellevue Hospital Medical College. His summary of the expedition was published as a news article in the New York Herald in the Fall of 1880, but his written diary was lost for 85 years until its discovery and publication by the Marine Historical Association of Mystic CT in 1965 [6]. This fascinating 117-page saga describes how Schwatka, a frontiersman and U.S. Army surgeon, collaborated with his Inuit guides to accomplish a remarkable feat of physical endurance.

In one notation, Schwatka provides an interesting insight into his weaning from their initial supply of carbohydrate-containing food.

"When first thrown wholly upon a diet of reindeer meat, it seems inadequate to properly nourish the system, and there is an apparent weakness and inability to perform severe exertive fatiguing journeys. But this soon passes away in the course of two or three weeks."

This observation, written a century before the current author first came to grips with the issue of "keto-adaptation", offers an early clue to resolve the dichotomy between impaired performance with low carbohydrate diets in the laboratory and their lack of debilitating effects when taken among people practiced in their use. That Schwatka was not impaired by his prolonged experience eating meat and fat is evidenced by his diary entry for the period 12–14 March 1880, during which he and an Inuit companion walked the last 65 miles in less than 48 hours to make a scheduled rendezvous with a whaling ship and complete his journey home.

Nutrition & Metabolism | Full text | A low-carbohydrate, ketogenic diet to treat type 2 diabetes

Nutrition & Metabolism | Full text | A low-carbohydrate, ketogenic diet to treat type 2 diabetes

Abstract
Background

The low-carbohydrate, ketogenic diet (LCKD) may be effective for improving glycemia and reducing medications in patients with type 2 diabetes.

[...]

Conclusion

The LCKD improved glycemic control in patients with type 2 diabetes such that diabetes medications were discontinued or reduced in most participants. Because the LCKD can be very effective at lowering blood glucose, patients on diabetes medication who use this diet should be under close medical supervision or capable of adjusting their medication.
Background

Prior to the advent of exogenous insulin for the treatment of diabetes mellitus in the 1920's, the mainstay of therapy was dietary modification. Diet recommendations in that era were aimed at controlling glycemia (actually, glycosuria) and were dramatically different from current low-fat, high-carbohydrate dietary recommendations for patients with diabetes [1,2]. For example, the Dr. Elliot Joslin Diabetic Diet in 1923 consisted of "meats, poultry, game, fish, clear soups, gelatin, eggs, butter, olive oil, coffee, tea" and contained approximately 5% of energy from carbohydrates, 20% from protein, and 75% from fat [3]. A similar diet was advocated by Dr. Frederick Allen of the same era [4].

Recently, four studies have re-examined the effect of carbohydrate restriction on type 2 diabetes. One outpatient study enrolled 54 participants with type 2 diabetes (out of 132 total participants) and found that hemoglobin A1c improved to a greater degree over one year with a low-carbohydrate diet compared with a low-fat, calorie-restricted diet [5,6]. Another study enrolled 8 men with type 2 diabetes in a 5-week crossover outpatient feeding study that tested similar diets [7]. The participants had greater improvement in glycohemoglobin while on the low-carbohydrate diet than when on a eucaloric low-fat diet. The third study was an inpatient feeding study in 10 participants with type 2 diabetes [8]. After only 14 days, hemoglobin A1c improved from 7.3% to 6.8%. In the fourth study, 16 participants with type 2 diabetes who followed a 20% carbohydrate diet had improvement of hemoglobin A1c from 8.0% to 6.6% over 24 weeks [9]. Only these latter three studies targeted glycemic control as a goal, and two of these were intensely-monitored efficacy studies in which all food was provided to participants for the duration of the study [7,8]. Three of the studies [6,8,9] mentioned that diabetic medications were adjusted but only one of them provided detailed information regarding these adjustments [9]. This information is critical for patients on medication for diabetes who initiate a low-carbohydrate diet because of the potential for adverse effects resulting from hypoglycemia.

The purpose of this study was to evaluate the effects of a low-carbohydrate, ketogenic diet (LCKD) in overweight and obese patients with type 2 diabetes over 16 weeks. Specifically, we wanted to learn the diet's effects on glycemia and diabetes medication use in outpatients who prepared (or bought) their own meals. In a previous article, we reported the results observed in 7 individuals [10]; this report includes data from those 7 individuals along with data from additional participants enrolled subsequently.

Watch out for the wrong kind of sugar

Watch out for the wrong kind of sugar

Watch out for the wrong kind of sugar

WE KNOW about good and bad fats. Now suspicion is growing that not all sugars are created equal either. Overweight adults who consume large amounts of fructose have been found to experience alarming changes in body fat and insulin sensitivity that do not occur after eating glucose.

Pure fructose is found in fresh fruit, fruit juice and preserves. But much of it sneaks into our diets though high-fructose corn syrup (HFCS) in soft drinks - which gets broken down into 55 per cent fructose and 45 per cent glucose in the body - or via sucrose (ordinary sugar), which is broken down into the same two sugars.

Fears that fructose and HFCS are fuelling the obesity epidemic and triggering insulin resistance and diabetes have been circulating for years (New Scientist, 1 September 2001, p 26), but there have been few direct investigations in humans.

So Peter Havel at the University of California, Davis, persuaded 33 overweight and obese adults to go on a diet that was 30 per cent fat, 55 per cent complex carbohydrates and 15 per cent protein for two weeks. For a further 10 weeks, they switched to a diet in which 25 per cent of their energy came from either fructose or glucose.

In those given fructose there was an increase in the amount of intra-abdominal fat, which wraps around internal organs, causes a pot belly and has been linked to an increased risk of diabetes and cardiovascular disease. This did not happen with the group who consumed glucose instead, even though both gained an average 1.5 kilograms in weight.

Those who consumed fructose also had raised levels of fatty triglycerides, which get deposited as intra-abdominal fat, and cholesterol. Their insulin sensitivity also fell by 20 per cent. Glucose appeared to have no effect on these measures. Havel presented the results at a meeting of the Endocrine Society in San Francisco last week.

Because Havel's test looked only at pure fructose, not HFCS or sucrose, it is not yet clear whether these substances are to blame for obesity and diabetes. "The question is, what is the amount of HFCS or normal sugar you need to consume to get these effects?" says Havel, who is planning a long-term study to find out. But he says it's not too soon for people with metabolic syndrome - the blend of conditions including belly fat and insulin resistance that raise the risk of diabetes and cardiovascular disease - to avoid drinking too many fructose-containing beverages.

PepsiCo, which sponsored Havel's research, disagrees. "This is a very interesting and important study," says a spokeswoman. "But it does not reflect a real-world situation nor is it applicable to PepsiCo since pure fructose is not an ingredient in any of our food and beverage products."

In a separate study, Havel's team compared the immediate effects of consuming a meal in which 25 per cent of the energy came from one of HFCS, sucrose, fructose or glucose. Blood triglyceride levels were all elevated to a similar level 24 hours after consuming fructose, sucrose or HFCS, but not glucose (The American Journal of Clinical Nutrition, vol 87, p 1194), suggesting that all three substances may have similar, negative health impacts. Longer-term studies are needed to confirm whether the triglycerides produced by sucrose or HFCS have similar effects to fructose on abdominal fat and insulin resistance.

Wednesday, July 30, 2008

Daily pill that halts Alzheimer's is hailed as 'biggest breakthrough against disease for 100 years' | Mail Online

Daily pill that halts Alzheimers is hailed as "biggest breakthrough against disease for 100 years" | Mail Online:

"A new drug halts the devastating progress of Alzheimer’s disease, say British scientists.

It is said to be more than twice as effective as current treatments.

A daily capsule of rember, as the drug is known, stops Alzheimer’s disease progressing by as much as 81 per cent, according to trial results.

Patients with the brain disorder had no significant decline in their mental function over a 19-month period.

‘We appear to be bringing the worst affected parts of the brain functionally back to life,’ said Dr Claude Wischik, who led the research.

It is the first time medication has been developed to target the ‘tangles’ in the brain that destroy nerve cells, leading to deteriorating memory.

The drug helps to disrupt this process, preventing the formation of new tangles and loosening those already created.

Last night the findings were hailed as the biggest breakthrough in the battle against Alzheimer’s since 1907."

Tuesday, July 29, 2008

The ketogenic diet may have mood-stabilizing prope...[Med Hypotheses. 2001] - PubMed Result

The ketogenic diet may have mood-stabilizing prope...[Med Hypotheses. 2001] - PubMed Result

The ketogenic diet may have mood-stabilizing properties.
El-Mallakh RS, Paskitti ME.

Department of Psychiatry and Behavioral Sciences, University of Louisville School of Medicine, Kentucky 40292, USA.

The ketogenic diet, originally introduced in the 1920s, has been undergoing a recent resurgence as an adjunctive treatment for refractory epilepsy, particularly in children. In this difficult-to-treat population, the diet exhibits remarkable efficacy with two-thirds showing significant reduction in seizure frequency and one-third becoming nearly seizure-free. There are several reasons to suspect that the ketogenic diet may also have utility as a mood stabilizer in bipolar illness. These include the observation that several anticonvulsant interventions may improve outcome in mood disorders. Furthermore, beneficial changes in brain-energy profile are noted in subjects on the ketogenic diet. This is important since global cerebral hypometabolism is a characteristic of the brains of depressed or manic individuals. Finally, the extracellular changes that occur in ketosis would be expected to decrease intracellular sodium concentrations, a common property of all effective mood stabilizers. Trials of the ketogenic diet in relapse prevention of bipolar mood episodes are warranted.

Monday, July 28, 2008

How High Fructose Corn Syrup Makes you Gain Weight

How High Fructose Corn Syrup Makes you Gain Weight

How High Fructose Corn Syrup Makes you Gain Weight

High Fructose Corn Syrup CandiesNew research from UT Southwestern Medical Center shows the amazing speed that our bodies make body fat from fructose. One of the reasons why low carb diets help you lose weight is that they reduce your intake of fructose.

Even though fructose, a type of sugar, is found naturally abundance in fruit, it is also added to many processed foods. Fructose is probably best known for its presence in the sweetener called high-fructose corn syrup (HFCS), which is typically 55 percent fructose and 45 percent glucose. It unfortunately has become the preferred sweetener for many food manufacturers. This is because it is cheaper, sweeter and easier to blend into beverages than table sugar.
Sugar Type As Important as Calories

Dr. Elizabeth Parks, lead author of the study , said her team’s findings infer that the right kind of carbohydrates you eat may be just as important in weight control as the number of calories you eat. The study appears in the Journal of Nutrition.

“The message from this study is powerful because body fat synthesis was measured immediately after the sweet drinks were consumed,” Dr. Parks said. “The carbohydrates came into the body as sugars, the liver took the molecules apart like tinker toys, and put them back together to build fats. All this happened within four hours after the fructose drink. As a result, when the next meal was eaten, the lunch fat was more likely to be stored than burned.

“This is an underestimate of the effect of fructose because these individuals consumed the drinks while fasting and because the subjects were healthy, lean and could presumably process the fructose pretty quickly. Fat synthesis from sugars may be worse in people who are overweight or obese because this process may be already revved up.”

Tuesday, July 22, 2008

Attention-Deficit Hyperactivity Disorder Related To Advantageous Gene

Attention-Deficit Hyperactivity Disorder Related To Advantageous Gene

Between 10,000 and 40,000 years ago, anthropologists concur that humans were developing the first signs of complex societies, replete with agriculture, rudimentary governments and the creation of cities for the first time. Humans also were rapidly expanding and exploring the planet. These revolutionary changes in human societies may have changed the forces that selected for certain genetic traits.

"Our data show that the creation of the 7R allele was an unusual, spontaneous mutation, which became an advantage for humans," Moyzis said. "Because it was an advantage, the gene became increasingly prevalent. This is very different from other genes that predispose to genetic disorders, where the mutations are detrimental. We believe this helps explain why a disorder with such a strong genetic association is so common today."

The researchers are now working on determining how the genetic variations in DRD4 may actually predispose individuals to ADHD and other behaviors, and on examining the relationship between other complex genetic variations and ADHD.

Is ADHD An Advantage For Nomadic Tribesmen?

Is ADHD An Advantage For Nomadic Tribesmen?

ScienceDaily (June 10, 2008) — A propensity for attention deficit hyperactivity disorder (ADHD) might be beneficial to a group of Kenyan nomads, according to new research. Scientists have shown that an ADHD-associated version of the gene DRD4 is associated with better health in nomadic tribesmen, and yet may cause malnourishment in their settled cousins.