Monday, November 17, 2008
Dr. Gabe Mirkin's Fitness and Health e-Zine November 9, 2008
Finally, a Clue to Explain Why You Should Avoid Red Meat
Several years ago, Professor Ajit Varki of the University of California, San Diego discovered a molecule called Neu5Gc that appears in the tissues of every mammal except humans (Proceedings of the National Academy of Sciences, September 29, 2003). Now he has put together the pieces of a puzzle that may explain why humans evolved with large brains and why, if we want to live into old age, we should probably avoid eating meat from any other mammals (Science, October 31, 2008).
His theory depends on evolution. Living creatures on earth started as one-celled organisms, progressed to 2 cells, and eventually to fish and birds. A mutation occurred in progressing to mammals, who developed the gene to make Neu5Gc.
Mammals progressed to apes and Neanderthals, and as humans evolved, Neu5Gc added a single oxygen atom to become a different molecule called Neu5Ac. So Neu5Gc is found in all mammals and their milks except humans. It is not in fish or birds.
Interestingly, the Neu5Ac molecule explains why humans are the only mammal to suffer from malaria. The malaria parasite cannot enter a cell until it grabs onto the Neu5Ac on the surface of human cells.
Many epidemiological studies show that people who eat red meat are at increased risk for heart attacks, strokes, at least
17 different cancers, diabetes, autoimmune diseases, arthritis and asthma. Scientists have blamed saturated fats or burnt fats, but this does not explain why red meat is linked to all of these
diseases while poultry, fish or saturated fats from plants are not.
Dr. Varki proposes another theory. When humans ingest the flesh or milk of any mammal, they absorb Neu5Gc and treat it the same way as an invading germ, so they make antibodies against it. This turns on their immunity and keeps it active so it eventually attacks the host itself, the human body. This is called chronic inflammation, which can lead to heart attacks, strokes, cancers and so forth.
Since humans cannot make Neu5Gc, any amount found
in human cells come from the mammals that they have eaten.
Neu5Gc is found in high levels in tumors, with the highest levels in metastasizing tumors. In our food supply, Dr. Varki found very high levels of Neu5Gc in beef, pork, lamb and goat, and moderately high amounts in milk and cheese. Low levels are found in turkey, duck, chicken and eggs; and negligible amounts occur in plants and seafood.
I stopped eating meat many years ago, and this report
makes me even more convinced that it should be avoided. I eat
lots of fruits, vegetables, whole grains, beans and nuts, as well as fish and shellfish. Eggs, long thought to be a harmful high- cholesterol food, now appear to be a healthful dietary staple.
While poultry appears to be a healthful food according to Dr.
Varki's theory, I still do not eat it. I do not drink milk and now plan to limit cheese as well.
Tuesday, November 11, 2008
Patricia Zifferblatt--November 11, 2008
Zinc is an essential mineral, necessary for sustaining all life. The US recommended dietary allowance of zinc from puberty through adulthood is 11mg for males and 8mg for females, with higher amounts recommended during pregnancy and lactation. Zinc is found in a wide variety of foods. Oysters contain more zinc per serving than any other food, but red meat and poultry provide the majority of zinc in the American diet. Other good food sources include beans, nuts, certain seafood, whole grains, fortified breakfast cereals, and dairy products. Anyone considering taking a zinc supplement should first consider whether their needs could be met by dietary zinc sources and from fortified foods. And yes, zinc toxicity is possible if too much is ingested in supplement form.
Zinc deficiency occurs where insufficient zinc is available for metabolic needs. It is usually nutritional, but can also be associated with malabsorption, acrodermatitis, enteropathica, chronic liver disease, chronic renal disease, sickle cell disease, diabetes, malignancy, and other chronic illnesses. Some signs to look for if you think you have a nutritional zinc deficiency are as follows. These indications of deficiency are not definitive conclusions but merely pointers. Only a medical doctor can diagnose symptoms and prescribe appropriate care.
White spots and/or ridges on nails
Stretch marks on skin
Hyperactivity in some children
Infertility and Miscarriages
Poor sense of smell and taste
Poor vision or night blindness
Source: Better Life Unlimited C. 2008
Wednesday, November 05, 2008
The Lies about Low Carbohydrate Diets
The articles on nutrition and some of the recipes on SparkPeople leave much to be desired. All of the information about Low Carbohydrate Diets is incorrect. Most of these arguments have appeared in print over the years often enough that even honest health professionals believe that there must be some truth behind it. If you read the 2002 edition of the New Dr Atkins Diet Revolution, Dr Atkins refutes all of these spurious claims. None of them are true. I am convinced that behind these claims are writers being paid by the fast food business, soft drink bottling industry, and giant food manufacturers who “add value” to basic food stuffs by refining it, bleaching it, sweetening it with High Fructose Corn Syrup, frying it in Trans Fats, adding preservative for shelf life, and mood exciters such as monosodium glutamate to enhance taste.
Based on a friends reminder of her positive experience and our reading of Atkins and my personal experience with Pritikin (anti-fat) and Center For Science in the Public Interest (pro-carb and anti-fat), my wife and I have started the Atkins Nutritional Approach ANA on 11-02-08 and plan to follow the program through all five of its stages and make it the basis for our nutrition for the rest of our life.
I’ve been following Dr. Mirkin’s well meaning dietary suggestions (D.A.S.H. Plus) for over two years and while it may have been a good program for active people with only a small amount of weight to lose, it hasn’t worked for me, even with 6-7 days a week of exercise. What is missing form Dr. Mirkin’s approach is the danger of excess carbohydrates for people with visceral fat, even from sources such as whole grains and legumes, which he recommends in abundant quantities. What he doesn’t recognize that while some people can handle higher level of carbohydrates, many people can’t. This later groups consists of people who suffer from Metabolic Syndrome and who will if following the typical carbohydrate recommendations will suffer heart and circulatory disease and diabetes. Dr. Mirkin doesn’t hold out hope for those over 100 pounds overweight and recommends lap band surgery.
For this group of people, including myself (not wanting to undergo lap band surgery, the Atkins Nutritional Approach is the best solution. I believe that it is also a great nutritional approach for everyone, but for those with visceral fat, the ones with the “apple” shaped bodies, it is a matter of life and death. The article in SparkPeople is totally irresponsible advice for this group. They should do their own research instead of relying on some industry paid hack writers to grind out the same old disproven objections to the Atkins Nutritional Approach.
Sunday, October 26, 2008
"As we surrender to what is, we experience greater calm and joy. Learn to wish that everything should come to pass exactly as it does."
- Dan Millman
Friday, October 24, 2008
Alison K. McConnell, BSc, MSc, PhD, FACSM, Professor of Applied Physiology, Centre for Sports Medicine & Human Performance, Brunel University
How Breathing and Rowing interact
Before discussing how breathing and rowing interact, its important to get a perspective on the unique 'animal' that is the world-class rower. In my view, it is no coincidence that rowers are renowned for the enormity of their lung capacity. The late Dr Mark Harries of the British Olympic Medical Centre once commented to Matthew Pinsent, 'My God man, you've got the lungs of a horse'. Sir Matthew's lung capacity is a whopping 8.25 litres, which is around 3 litres bigger than the 'average Joe', and 2 litres bigger than it should be for a man of his size. In his prime, his maximal oxygen uptake was around 8 litres per minute and his maximal ventilation around 300 litres per minute. Rowing a 2000m at ~460W, he respired approximately 1700 litres of air, and his inspiratory muscle power output was ~85W. The next time you're in the gym, dial up 85W on a cycle ergometer and see how this feels - it's a surprisingly large amount of work.
So what is it about having big lungs that is an advantage to a rower? I do not believe that it is because it gives them a greater VO2max; instead, I believe that having larger lungs enables rowers to maintain good breathing discipline during rowing. We'll consider this further in the section on the mechanical limitations imposed by breathing.
It has long been recognized that experienced rowers entrain their breathing to rowing stroke rate. Experienced rowers tend to confine their breathing to two main patterns; i) one expiration per drive and one inspiration during recovery (1:1), or ii) one complete breath during the drive and one complete breath during recovery (2:1). Research has shown that tidal volume (the volume of each breath) is constrained above a certain power output, with further increases in ventilation being brought about by increasing breathing frequency3. Some researchers have gone as far as to suggest that at high work rates, stroke rate may be dictated by the drive to breathe3, which reinforces the potent interrelationship of these two factors.
The linkage between stroke rate and breathing pushes the respiratory muscles to their limits. During a 2000m race, athletes commonly try to maintain the 2:1 breathing pattern; they breathe out during the initial part of the drive (when the blade is in the water), take a breath as they reach the end of the drive, breathe out again as they begin to come forward and take a small breath just before the 'catch'. This small breath at the catch is very important in terms of allowing the effective transmission of force from the stretcher to the blade handle (see 'Breathing related limitations to rowing: Mechanical').
In rowing, the same muscles that we use to breathe are also used for maintaining posture, 'core stability' and transmission of force during the drive phase of the stroke (see 'Breathing related limitations to rowing: Mechanical'). There are a number of critical points in the stroke where differing demands are placed upon the inspiratory muscles. At the finish, the hips are extended and the shoulders are behind the hips. This means that the muscles of the trunk must work against gravity to prevent the rower from falling backwards. At the same time, the rower needs to take a large, fast breath, which means that the inspiratory muscles are subjected to competing demands for postural stability and breathing. Once the rower reaches the catch, they must take another breath, but in this position, the movement of the diaphragm is impeded by the crouched body position. At the catch, the abdomen is compressed by the thighs pushing the liver, stomach and gut upwards against the diaphragm. This compression makes it harder for the diaphragm to contract, flatten and move downwards, as it must do in order to inflate the lungs. During the drive, the inspiratory muscles are subjected to competing demands for breathing, postural and force transmission. All in all, rowing places some varied and 'extreme' demands on the inspiratory muscles.
The combination of these demands renders the inspiratory muscles of rowers at heightened risk of becoming fatigued. Indeed, research has shown that the strength of the inspiratory muscles is 12-20% lower following a 2000m race4, 5.
Most readers would agree that if fatigue is present in a group of muscles following a given task, these muscles are probably placing some limitation on the performance of that task. The earliest reports of breathing muscle fatigue following a competitive event appeared in the early 1980s, where significant declines in inspiratory muscle strength were observed following marathon running6. Later research confirmed these findings following marathon running7, but also provided data suggesting that ultra-marathon8 and triathlon9 competition were fatiguing to the respiratory system.
Under laboratory, and field-based research conditions, my own research group has also demonstrated inspiratory muscle fatigue following rowing4, 5, cycling10 and swimming11, as well as a sprint triathlon12. This evidence of exercise-induced inspiratory muscle fatigue is probably the most compelling rationale for specific training of the inspiratory muscles. Readers who are interested in this topic are referred to the article on POWERbreathe® training by Eddie Fletcher in this section of the website.
Breathing related limitations to rowing: Mechanical
The mechanics of rowing are such that breathing must be entrained to stroke rate (see above). Failure to do so is not only uncomfortable, but also jeopardizes the efficiency of the mechanical linkage between the blade handle and the major force producers of the lower body. In open class oarsmen, the forces driven from the stretcher, through the body and to the blade handle can be in the order of 900 Newtons (the weight of two bags of cement, or almost two hundred weight). Since the main force generators for the rowing stroke are located below the waist, if force is to be transmitted effectively to the blade handle, it must be transferred effectively through the trunk.
The diaphragm is the main inspiratory muscle, but it also plays an important role in postural control and the maintenance of intra-abdominal pressure (this is the pressure inside the abdominal compartment). Without an increase in intra-abdominal pressure when we lift objects, or exert force during a rowing stroke, the spine and pelvis are unstable. Under these conditions, the trunk flexes and fails to transmit the force generated by the lower body effectively to the object in our hands (be it a blade handle or a suit case). Why does this matter? Well consider the difference in mechanical efficiency of using a crow bar to lever something open compared with using a rod of metal that contains a number of loose joints. If the joints move, the force the rod transits is lower, and its efficiency is reduced. The jointed rod in this analogy is your spine, and failure to maintain a stiff trunk reduces the efficiency of force transmission during the stroke. Central to generating this stiffness is the contraction of the diaphragm.
So what's this got to do with breathing? The pre-catch breath is important for maintaining the safe transmission of force, because the structural stability of the rib cage and lower back are affected by the pressures inside the chest and abdominal cavities, respectively. During the drive, the muscles of the trunk brace against the partially inflated lungs, allowing the internal pressures within the chest and abdomen to increase; this stiffens the trunk. Failure to maintain adequate internal pressures (because of an inadequate lung volume) may lead to an increased risk of rib stress factures and low back injury.
Furthermore, in an unpublished pilot study my research group has demonstrated that when the inspiratory muscles (including the diaphragm) are fatigued, the maximal static force generated at the catch is reduced. This suggests that the inspiratory muscles play a role in determining either, the magnitude of the force generated by the lower body, or the efficiency of its transmission through the trunk, or both.
So we can see that the muscles of the trunk have a number of important roles during rowing, 1) contributing to the transmission of propulsive force, 2) maintaining structural stability of the spine and other bony structures, and 3) breathing. However, these roles may become contradictory from time to time, which may impact negatively upon both performance and injury risk. Research has shown that when 'push comes to shove', the diaphragm's role in breathing takes precedence over its role in postural stability13. In other words, in situations of high ventilatory demand, such as exercise, the postural role of the inspiratory muscles is compromised, and it has been suggested that this may lead to an increased risk of injury due to spinal instability and a loss of postural control13. This means that when breathing discipline breaks down during rowing, the risk of injury increases, and performance is impaired.
What can we do to minimize these negative mechanical effects of breathing? A well-established method of increasing the fatigue resistance of any muscle is to resistance train it; stronger muscles work at lower relative intensities than weaker muscles, so their endurance and risk of fatigue are reduced. There is now good evidence that specific training of the inspiratory muscle using the POWERbreathe® improves performance in a range of sport, especially rowing4, 5. For more information on this POWERbreathe® training see Eddie Fletcher's article on this section of the website.
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