Monday, June 25, 2012

The China Study

Per recommendation from my mother, I've started to read "The China study".  She and I both have an interest in nutrition and disease so I am excited to read the book and gather new insights - and maybe find a new lifestyle ideal to work towards.  I have only started to read the book, but from what I gather, the author is going to build a case that animal products and specifically animal protein in the Western diet is responsible for many of the common diseases that afflict us, including heart disease, cancer, and obesity. 

As I was reading the first chapter, my mind wandered a bit and I remembered the time I spent in east Africa.  The Maasai people are nomads who live in the Great Rift Valley of Kenya and Tanzania and we had many encounters with them on our trip.  Their economy revolves around cattle - they are nomads because they must find new grazing lands for their herds.  Maasai diet is extremely high protein:  they drink milk from their cows and even harvest cow blood from a small cut in the jugular vein to drink raw.  They will consume meat from goats, sheep, and their cattle if they need to.

From the New England Journal of Medicine, on the Masai Diet, from 1971:

"The Masai of East Africa exhibit some unique biologic characteristics. Despite their customary diet composed of 66 per cent calories as fat, they have persistent low serum cholesterol and beta-lipoprotein levels. Post-mortem examinations provided direct proof of a paucity of atherosclerosis. Metabolic studies revealed that the Masai absorbed large amounts of dietary cholesterol, but also possessed a highly efficient negative feedback control of endogenous cholesterol biosynthesis to compensate for the influx of dietary cholesterol.  The high ratios of phospholipid to cholesterol and bile acid to cholesterol in their gallbladder bile explain the extreme rarity of cholesterol gallstones. All these characteristics may reflect a long-term biologic adaptation of the tribe."

I don't think this refutes anything, it is just food for thought.  For example, it seems plausible to me that relative dietary protein excess could be related to "Western" diseases but if such protein is immediately utilized that might be a different story.  The Maasai eat a lot of animal protein but they are also nomads and spend their days in different ways than your average American and probably make more use of the protein in their diets.  Also, I'm not aware of any good studies of cancer among the Maasai but I will keep looking.

Switching gears.  On page 80 off the book I made a self-serving observation:  there was not a statistically significant link between eggs and blood cholesterol found in the China study.  After some arguments with friends about the relative health risks/benefits of eating eggs, I had previously scoured pubmed for links between egg consumption and blood cholesterol.  After viewing multiple studies, I was able to find no such link - only transient increases in blood cholesterol were reported (immediately after consumption). 

From a scientific perspective I wouldn't be totally shocked if eggs were ultimately shown to be fairly benign dietary additions.  I am about to embark on a path of pure unadulterated, unsupported speculation (as I often do).  If there is something unique about animal protein and animal cholesterol as it relates to cancer, causing tumor progression, I wouldn't be surprised if it ultimately proved to be related to the consumption of signalling molecules & growth factors that feed malignancy.  Consuming "animal protein" essentially is an exercise in consuming the cells of various animal tissues.  Those cells all have membranes that are full of cholesterol molecules and transmembrane signalling proteins.  Those cells will also contain a cytoplasm full of hormones,intracellular signalling molecules, enzymes, signal amplifiers, and the like.

Eggs wouldn't necessarily have those things because eggs aren't tissue.  Its a protoplasm of undifferentiated nutrients that will ultimately be built into differentiating (specializing) cells and tissues.  Raw eggs just represent building blocks for later animal protein.  The animal protein in eggs would lack signalling molecules and hormones.

Anyway, I will be curious to see if there is stronger anti-egg evidence later in the book.

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