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Posts Tagged ‘transsulfuration’


Transthyretin and Lean Body Mass in Stable and Stressed State

Curator: Larry H Bernstein, MD, FCAP

Chapter 20
Plasma Transthyretin Reflects the Fluctuations
of Lean Body Mass in Health and Disease
Yves Ingenbleek
Abstract

Transthyretin (TTR) is a 55-kDa protein secreted mainly by the choroid plexus and the liver. Whereas its intracerebral production appears as a stable secretory process allowing even distribution of intrathecal thyroid hormones, its hepatic synthesis is influenced by nutritional and inflammatory circumstances working concomitantly. Both morbid conditions are governed by distinct pathogenic mechanisms leading to the reduction in size of lean body mass (LBM). The liver production of TTR integrates the dietary and stressful components of any disease spectrum, explaining why it is the sole plasma protein whose evolutionary patterns closely follow the shape outlined by LBM fluctuations. Serial measurement of TTR therefore provides unequalled information on the alterations affecting overall protein nutritional status. Recent advances in TTR physiopathology emphasize the detecting power and preventive role played by the protein in hyperhomocysteinemic states, acquired metabolic disorders currently ascribed to dietary restriction in water-soluble vitamins. Sulfur (S)-deficiency is proposed as an additional causal factor in the sizeable proportion of hyperhomocysteinemic patients characterized by adequate vitamin intake but experiencing varying degrees of nitrogen (N)-depletion. Owing to the fact that N and S coexist in plant and animal tissues within tightly related concentrations, decreasing LBM as an effect of dietary shortage and/or excessive hypercatabolic losses induces proportionate S-losses. Regardless of water-soluble vitamin status, elevation of homocysteine plasma levels is negatively correlated with LBM reduction and declining TTR plasma levels. These findings occur as the result of impaired cystathionine-b-synthase activity, an enzyme initiating the transsulfuration pathway and whose suppression promotes the upstream accumulation and remethylation of homocysteine molecules. Under conditions of N- and S-deficiencies,the maintenance of methionine homeostasis indicates high metabolic priority.
Y. Ingenbleek
Laboratory of Nutrition, University Louis Pasteur Strasbourg
e-mail: yves.ingenbleek@wanadoo.fr
S.J. Richardson and V. Cody (eds.), Recent Advances in Transthyretin Evolution, 329
Structure and Biological Functions,
DOI: 10.1007/978‐3‐642‐00646‐3_20, # Springer‐Verlag Berlin Heidelberg 2009

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Vegan Diet is Sulfur Deficient and Heart Unhealthy

Larry H. Bernstein, MD, FCAP, Curator

 

The following is a reblog of “Heart of the Matter: Plant-Based Diets Lead to High Homocysteine, Low Sulfur and Marginal B12 Status”
Posted on September 26, 2011 by Dr Kaayla Daniel in WAPF Blog and tagged B12, Forks over Knives, Kaayla T. Daniel, Kilmer S. McCully, Yves Ingenbleek

It is a report of a scientific study carried out by Kilmer S. Cully and Yves Ingenbleek, Harvard Pathology and Univ Louis Pasteur.  I have previously written about the conundrum of transthyretin as an accurate marker of malnutrition, but also being lowered by the septic state.  This is accounted for by the catabolic state that sets off autocannabalization of skeletal muscle and lean body mass to provide gluconeogenic precursors to sustain life.  While serum albumin and transthyretin both decline, the former has a half-life of 20 days, while the latter is 48 hours.  Much work has been done to gain a better understand this rapid turnover protein that transports thyroxine, and the immediate result of the decline in concentration is a shift the the hormone protein binding equilibrium increasing the free thyroxine, a euthyroid hyperthyroid effect.  However, much work by Prof. Inglenbleek, some ion collaboration with Vernon Young, at MIT, showed that transthyretin reflects the sulfur stores of animals.  The sulfur to nitrogen ratio of plants is 1:20, but it is 1:12 in man, so the dietary intake would affect an omnivorous animal.  Recall that S is carried on amino acids that take part in disulfide linkage.  A deficiency in S containing amino acids would have a negative health effect.  The story is presented here.

The World Health Organization (WHO) reports that 16.7 million deaths occur worldwide each year due to cardiovascular disease, and more than half of those deaths occur in developing countries where plant-based diets high in legumes and starches are eaten by the vast majority of the people.

Yet “everyone knows” plant-based diets prevent heart disease.  Indeed this myth  is repeated so often that massive numbers of educated, health-conscious individuals in first world countries are consciously adopting third world style diets in the hope of preventing disease, optimizing health and maximizing longevity.   But if the WHO statistics are correct, plant-based diets might not be protective at all.   And today’s fashionable experiment in veganism could end very badly indeed.

A study out August 26 in the journal Nutrition makes a strong case against plant-based diets for prevention of heart disease.  The title alone  –  “Vegetarianism produces subclinical malnutrition, hyperhomocysteinemia and atherogenesis” — sounds a significant warning.   The article establishes  why subjects who eat mostly vegetarian diets develop morbidity and mortality from cardiovascular disease unrelated to vitamin B status and Framingham criteria.

Co-author Kilmer S. McCully, MD, “Father of the Homocysteine Theory of Heart Disease,” is familiar to WAPF members as winner of the Linus Pauling Award, WAPF’s Integrity in Science Award, and author of numerous articles published in peer-reviewed journals as well as the popular books The Homocysteine Revolution and The Heart Revolution.   In 2009 Dr. McCully was one of the signers of the Weston A. Price Foundation’s petition to the FDA in which we asked the agency to retract its unwarranted 1999 soy/heart disease health claim.  (http://www.westonaprice.org/soy-alert/soy-heart-health-claim)

Dr. McCully teamed up with Yves Ingenbleek, MD, of the University Louis Pasteur in Strasbourg, France, which funded the research.   Dr. Ingenbleek is well known for his work on malnutrition, the essential role of sulfur to nitrogen, and sulfur deficiency as a cause of  hyperhomocysteinemia.

The study took place in Chad, and involved 24 rural male subjects age 18 to 30, and 15 urban male controls, age 18-29.   (Women in this region of Chad could not be studied because of their animistic beliefs and proscriptions against collecting their urine.)

The rural men were apparently healthy, physically active farmers with good lipid profiles.  Their staple foods included cassava, sweet potatoes, beans, millet and ground nuts.   Cassava leaves, cabbages and carrots provided good levels of carotenes, folates and pyridoxine (B6).  The diet is plant-based there because of a shortage of grazing lands and livestock, but subjects occasionally consume  some B12-containing foods, mostly poultry and eggs, though very little dairy or meat.   Their diet could be described as high carb, high fiber,  low in both protein and fat, and low in the sulfur containing amino acids.    In brief, the very diet recommended by many of today’s nutritional “experts” for overall good health and heart disease prevention.

The urban controls were likewise healthy and ate a similar diet, but with beef, smoked fish and canned or powdered milk regularly on the menus.  Their diet was thus higher in protein, fat and the sulfur-containing amino acids though roughly equivalent in calories.

Dr. McCully’s research over the past 40 years on the pathogenesis of atherosclerosis has shown the role of homocysteine in free radical damage and the protective effect of  vitamins B6, B12 and folate.   Indeed, many doctors today recommend taking this trio of B vitamins as an inexpensive heart disease “insurance policy.”

In Chad, both groups showed adequate levels of B6 and folate.  The B12 levels of the vegetarian group were lower, but the difference was only of “borderline significance.”   However, as the researchers point out, ”A previous study undertaken in the same Chadian area in a larger group of 60 rural participants did demonstrate a weak inverse correlation between B12 and homocysteine concentrations in the 20 subjects most severely protein depleted .  .  .  It is therefore likely that the hyperhomocysteinemia status of some of our rural subjects in the present survey might have resulted from combined B12 and protein deficiencies.   The correlation of B12 deficiency with hyperhomocysteinemia could well reach statistical significance if a larger groups of subjects were studied.”

Clearly it’s wise for people on plant-based diets to supplement their diets with B12, but protein malnutrition must also be addressed.   And the issue is not just getting enough protein to eat, but the right kind.   Quality, not just quantity.   The bottom line is we must eat  protein rich in bioavailable, sulfur-containing amino acids — and that means animal products.   (Vegans at this point will surely claim the issue is insufficient protein and trot out soy as the solution.   Soy is indeed a  complete plant based protein, but notoriously low in methionine.  It does contain decent levels of cysteine, but the cysteine is bound up in protease inhibitors, making it largely  biounavailable. (For more information, read  my book The Whole Soy Story: The Dark Side of America’s Favorite Health Food, endorsed by Dr. McCully, as well as our petition to the FDA noted above.)

So what did  Drs. Ingenbleek and  McCully find among the study group of protein-deficient people?   Higher levels of homocysteine, of course.  Also significant alterations in body composition,  lean body mass, body mass index and plasma transthyretin levels.  In plain English, the near-vegetarian subjects were thinner, with poorer muscle tone and showed subclinical signs of protein malnutrition.   (So much for popular ideas of extreme thinness being healthy. )

The plant-based diet of the study group was low in all of the sulfur-containing amino acids.   As would be expected, labwork on these men showed lower plasma cysteine and glutathione levels compared to the controls.  Methionine levels, however,  tested comparably.   The explanation for this is  “adaptive response.”   In brief, mammals trying to function with insufficient sulfur-containing amino acids will do whatever’s necessary to survive.   Given the essential role of methionine in metabolic processes, that means deregulating the transsulfuration pathway, increasing homocysteine levels, and methylating homocysteine to make methionine.

Ultimately, it all boils down to our need for sulfur.   As Stephanie Seneff, PhD, and many others have written in Wise Traditions and on this website, sulfur is vital for disease prevention and maintenance of good health.   In terms of heart disease, Drs. Ingenbleek and McCully have shown sulfur deficiency not only leads to high homocysteine levels, but is the likeliest reason some clinical trials using B6, B12 and folate interventions have proved ineffective for the prevention of cardiovascular and cerebrovascular diseases.    Over the past few years, headlines from such studies have led to widespread dismissal of Dr. McCully’s  “Homocysteine Theory of Heart Disease” and renewed media focus on cholesterol, c-reactive protein and other possible culprits that can be treated by statins and other profitable drugs.   In contrast, Drs. McCully and Ingenbleek research suggests we can better prevent heart disease with three inexpensive B vitamins and traditional diets rich in the sulfur-containing amino acids found in animal foods.

In the blaze of publicity surrounding Forks Over Knives and other blasts of vegan propaganda, few people are likely to hear about this study.   That’s sad, for it provides an important missing piece in our knowledge of heart disease development, a strong argument against the plant-based fad, and a bright new chapter in what the New York Times has called “The Fall and Rise of Kilmer McCully.”

*  *  *  *  *

Thanks to Sylvia Onusic PhD who was able to access a full text copy of this article to share with  me.

This entry was posted in WAPF Blog and tagged B12, Forks over Knives, Kaayla T. Daniel, Kilmer S. McCully, Naughty Nutritionist, soy, sulfur, Yves Ingenbleek. Bookmark the permalink.

Sylvia says:

September 26, 2011 at 5:32 pm

Kaayla, I found the article but you brought it to life- what a great explanation backed by high levels of knowledge and analysis. We are grateful for your numerous contributions to the field of health!
Thanks so much.

Sylvia Onusic

 

 

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