Dr. Tom Greenfield

A study on the effects of milk consumption on growth hormone (GH) and insulin-like growth factor 1 (IGF-1) in children suggests that milk drinking may cause increases in pituitary growth hormone levels of prepubertal girls and boys.

The article, published in Nutrition Journal[1] measured the effects of drinking three 8-ounce tetrapak “boxes” (710 ml) of conventional U.S. UHT-pasteurized vitamin D fortified whole milk daily for one month (the producer of the milk accepts milk only from dairies that do not use bovine somatotropin). A class of Mongolian children (who rarely consume milk) were compared with American children: the Mongolian children experienced rapid linear growth (the equivalent of 12 cm/year) compared to an average height velocity of 5-6 cm/year in U.S. children age 10-11 years. It is suggested that this was not the effects of correcting undernutrition, but that milk intake may raise GH levels. This is a novel finding, and the authors suggest that "nutrients or bioactive factors in milk may stimulate endogenous GH production," that is, secretion of hormones from the pituitary gland may be increased by drinking milk.

Apart from stimulating abnormal growth in prepubertal children, what could be the long-term side-effects of an increase in the pituitary growth hormone in those with otherwise normal growth hormone levels? Another study [2] notes how GH/IGF-1 provides an anti-apoptotic environment (a situation where programmed cell death is delayed) that may favour survival of genetically damaged cells.

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The ability to digest starch may have given our human ancestors an evolutionary advantage in certain circumstances, according to an article by George Perry et al. in Nature Genetics.[1] The enzyme amylase, secreted by salivary glands (and also by the pancreas), helps to hydrolyse or break down starch in the diet when mixed with water. The gene that produces the enzyme in saliva, called AMY1, is on chromosome 1, other authors have theorised that the salivary amylase gene evolved from the pancreatic amylase gene via an upstream retrovirus insertion.[2]

Perry's team took salivary and DNA samples from people of Datog, Hadza, Mbuti, Biaka, Japanese, Yakut and European-American populations and analysed their typical dietary protein and starch intake. The results indicate that geographically distinct groups of humans tend to have variable levels of the AMY1 gene according to the level of starch in their diets: Those whose diets consist of higher protein levels tended to have on average fewer copies of the gene, and vice versa. More copies of the gene leads to a higher level of salivary amylase. Fruit-eating chimpanzees however have few copies of the gene. The authors suggest that: "This behavioral variation raises the possibility that different selective pressures have acted on amylase", i.e. it could be evidence for genetic adaptation to the availability of starch in the environment.

Another study in the American Journal of Human Genetics[3] published just a month prior to Perry's article suggests that the gene for lactase persistence (LP, the ability to digest the lactose sugar in milk after childhood) came about through evolution of two groups geographically and chronologically distinct, and that "there is a still-ongoing process of convergent evolution" of the LP alleles in humans".

It appears that we are still evolving according to what we eat, but can our genes keep up with the pressures inflicted on us by modern western diets?

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Announcing two lectures at the RDS in Dublin, Ireland. This year the date and location have changed, so check the website for details.

Both lectures are on Saturday 1st September 2007; in the first lecture at 1.00 pm Tom Greenfield ND will introduce the concept of the GenoType Diet in the forthcoming book by Dr. Peter D'Adamo ND. The venue is the Nutrition Theatre, places are limited.

In the second lecture at 4.00 pm Ingrid Greenfield of Artisan Bread Original will be demonstrating how to make sandwiches compatible with all blood groups, and samples for tasting will be available. The venue is Centre Hall.

Both speakers will be available at the Artisan Bread stand in the main exhibition hall on Saturday and Sunday.

There is a charge for entry to the event on the day, but free tickets can be obtained in advance from the website.

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The IfHI Conference 2007 - The Buttes, Phoenix, AZ.

What a great conference: lots of speakers with new information on genetics and individuality, all giving the background information for the new concept revealed by Dr. D'Adamo.

The Book The GenoType™ Diet is to be on sale from December 26th, 2007. The concept takes us beyond blood types, to a new categorisation of 6 distinct genotypes:

Although these genotypes include blood group and secretor status information, they do not all exclusively relate to one single blood type: individuals fitting into certain genotypes may have one of several possible blood types. The new additions to the genotypes over and above the genetic information associated with blood types includes many easily accessible measurements:

These are associated with 'epigenetic' factors that do not change the actual genes of the individual, but influence how they are expressed, like a volume control that can be moved up or down to vary the amount that a certain gene interacts with the environment.

Other influencing factors on a person's genotype include both ancestral DNA haplogroups and ayurvedic doshas. It looks like the result will be the fusion of ancient wisdom, anthropometric techniques from the last century, and modern cutting edge genetic science - with a strong influence from the blood type information that is associated with diet and health.

Each genotype has different disease risks and health benefits, and the book will outline the best preventitive strategies for each type. It promises to be a new generation of naturopathic medicine.

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The UK Human Fertilisation and Embryology Authority (HFEA) has agreed in principle to screening and selection of embryos for couples who have the possibility of passing on a gene for breast cancer.

Previously genetic screening has only been carried out for embryos with the risk of having a gene that always causes disease, such as cystic fibrosis.

Now the HFEA are allowing screening of genes on a case by case basis that would give the individual an increased risk of disease, such as the BRCA1 gene, which raises the risk of cancer in adulthood by 60-80%.

Comment:

This kind of approach can be seen as a move away from human genetic diversity and the concept of addressing the environmental influences of switching genes on or off, towards a genetic inbreeding and the kind of uniformity depicted by Huxley.

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