NEW YORK (Reuters Health) - A person's native climate might influence how his
or her body goes about burning calories, according to a study published Monday.
People whose ancestors hail from chilly regions have gene adaptations that may
allow their bodies to produce more heat while burning calories, an
international team of researchers reports, while those with roots in warmer
climates use calories more efficiently and produce scant excess heat.
Mitochondria, found in every cell, are responsible for producing energy and
play a key role in regulating metabolism. The DNA in mitochondria is inherited
maternally, and shows "striking differences" from one geographic region to
another, Douglas C. Wallace from the University of California at Irvine and
colleagues note. To investigate whether adaptation to different climates might
explain this variation, the researchers analyzed gene sequences from the
mitochondria of 104 people who represented all the known major types of
mitochondrial DNA.
In the Proceedings of the National Academy of Sciences paper, Wallace and his
team report that mitochondrial gene variants may confer advantages in some
climates, but disadvantages in others.
For instance, arctic and sub-arctic native peoples had variants that programmed
them to produce more heat, but put out less energy. Their bodies were thus more
efficient at keeping them warm. Previous studies have shown that indigenous
populations around the North and South Poles tend to have a higher resting
metabolism.
Tropical and sub-tropical natives made more efficient use of energy, producing
little heat.
The authors say the variants are evidence of natural selection at work--that
genes evolved in response to environmental stresses.
But this adaptive response might not be beneficial when people native to one
climate relocate to another climate, the authors say. "Given that mitochondrial
DNA lineages are functionally different, it follows that the same variants that
are advantageous in one climatic and dietary environment might be maladaptive
when these individuals are placed in a different environment," they write.
Natives of cold regions are used to stoking their bodies with heat-producing
high-calorie meals. That dietary habit might not serve them well if they move
to a warmer region, and may play a role in causing disease, the authors say.
"Ancient regionally beneficial mitochondrial DNA variants could be contributing
to modern bioenergetic disorders such as obesity, diabetes, hypertension,
cardiovascular disease, and neurodegenerative diseases as people move to new
regions and adopt new lifestyles," they write.
Proceedings of the National Academy of Sciences 2002;10.1073/pnas.0136972100
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COMMENT BY: William Wolcott
Founder, The Healthexcel System of Metabolic Typing
Author,
The Metabolic Typing Diet
(Doubleday, 2000)
This study lends credence to our philosophy of metabolic typing of the last 25
years that we are as unique on a biochemical level as we are in our
fingerprints. People differ in how their bodies metabolize nutrients. What
constitutes a healthy diet for one metabolic type may produce pathology in a
different metabolic type. Forces of natural selection, genetic mutation, and
survival of the fittest assured that the indigenous people of a certain
geographical and climatic region became perfectly adapted to the foods in their
environment. This same scenario played itself out throughout the planet.
The author's statement, "...the same variants that are advantageous in one
climatic and dietary environment might be maladaptive when these individuals
are placed in a different environment," echoes the research of metabolic typing
pioneer George Watson, Ph.D. Watson spent some 30 years objectifying indicators
of what he termed Fast Oxidizers and Slow Oxidizers. Watson found that Fast
Oxidizers metabolized carbohydrates too quickly and as a result tended toward
an acid blood pH and thereby thrived on a diet high in proteins and fats and
low in carbohydrates. Slow Oxidizers with an alkaline blood pH required a diet
high in carbohydrates and low in proteins and fats in order to acidify the
blood. Watson further showed that the right diet for the metabolic type
resolved health issues but that when the diets were transposed, pathologies
worsened.
Each of us today carries the genes of our ancestors and the genetic
predisposition to thrive on certain foods and decline on other foods. The
secret of the right diet for each person depends not on whim, fancy or
philosophy but is irrefutably dictated by our genes. Eating right for your
metabolic type should be the foundation of any quest for good health.