Fatty food cravings genetically programmed

July 18, 2011 by Deborah Braconnier, Medical Xpress report

(Medical Xpress) -- In a new study published in Neuropsychopharmacology, Dr. Alasdair MacKenzie has found a genetic switch that regulates thirst and appetite and is believed to be the reason many people from Western countries are more prone to high fat diets and alcohol consumption that those in Asian countries.

Researchers believe this switch was turned on during the Ice Age when it was necessary for Europeans to consume high fat diets and higher alcohol content in order to survive the conditions. The complications seen from fat and alcohol were not a problem back then because the was between 30 and 40 years.

The switch is located in an area of the brain called the hypothalamus and regulates appetite and thirst and controls the galanin gene. According to the researchers, the stronger the switch is turned on, the more likely a person is to crave and consume higher fat content foods. The weaker version of this switch was only found in 16 percent of Europeans compared to 30 percent of Asians studied.

Galanin is also produced in the amygdala and controls anxiety and fear. The researchers found that this switch is also active in the amygdala and could play a role on the emotional state of an individual and depression.

Researchers hope that the discovery of this switch and how it affects could lead to future treatments in obesity and weight control. Because of the connection to emotional states, this switch could also play a role in future depression treatments.

More information: Differential Activity by Polymorphic Variants of a Remote Enhancer that Supports Galanin Expression in the Hypothalamus and Amygdala: Implications for Obesity, Depression and Alcoholism; Scott Davidson, Marissa Lear, Lynne Shanley, Benjamin Hing, Amanda Baizan-Edge, Annika Herwig, John P Quinn, Gerome Breen, Peter McGuffin, Andrew Starkey, Perry Barrett and Alasdair MacKenzie; Neuropsychopharmacology , (29 June 2011) doi:10.1038/npp.2011.93

Abstract
The expression of the galanin gene (GAL) in the paraventricular nucleus (PVN) and in the amygdala of higher vertebrates suggests the requirement for highly conserved, but unidentified, regulatory sequences that are critical to allow the galanin gene to control alcohol and fat intake and modulate mood. We used comparative genomics to identify a highly conserved sequence that lay 42 kb 5′ of the human GAL transcriptional start site that we called GAL5.1. GAL5.1 activated promoter activity in neurones of the PVN, arcuate nucleus and amygdala that also expressed the galanin peptide. Analysis in neuroblastoma cells demonstrated that GAL5.1 acted as an enhancer of promoter activity after PKC activation. GAL5.1 contained two polymorphisms; rs2513280(C/G) and rs2513281(A/G), that occurred in two allelic combinations (GG or CA) where the dominant GG alelle occurred in 70-83 % of the human population. Intriguingly, both SNPs were found to be in LD (R2 of 0.687) with another SNP (rs2156464) previously associated with major depressive disorder (MDD). Recreation of these alleles in reporter constructs and subsequent magnetofection into primary rat hypothalamic neurones showed that the CA allele was 40 % less active than the GG allele. This is consistent with the hypothesis that the weaker allele may affect food and alcohol preference. The linkage of the SNPs analysed in this study with a SNP previously associated with MDD together with the functioning of GAL5.1 as a PVN and amygdala specific enhancer represent a significant advance in our ability to understand alcoholism, obesity and major depressive disorder.

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zafouf
not rated yet Jul 18, 2011
I know that fat is like other foods in that you get used to the amount you eat. I'm Caucasian, I eat a very lowfat diet, and I have no cravings for fat at all. I take an omega-3 supplement, and I often get behind on taking it because I prefer carbs.
I've found sugar is similar. If you use sugar sparingly, small amounts taste sweet enough. If you use a lot of sugar, you need a lot of sugar to make drinks taste sweet enough.
Similarly for salt of course. Unsalted food tastes fine if you rarely eat salty food.
Jesse_EngAmer
1 / 5 (1) Jul 19, 2011
Thanks for the post. In addition, for years the USDAs food pyramid backed by the FDA has been a major contributor to our growing, pardon the pun, obesity problem. Between toxins in the food supply and the allowance of horrid quality food and related dietary advice, our government bears a major portion of responsibility for the obesity epidemic in America today. (wellnessresources.com)

Taste develop, grow and change. But they also grow accustomed and desensitized in a sense. The FDAs approved additives such as aspartame are largely responsible for Americas insatiable need for junk food and sweets. Call it conditioning if you will. Aspartame may be the largest cause of health problems in America. It is an excitotoxin. Excitotoxins cross the blood-brain barrier unrestricted. They contribute all manner of neurological disorders. It attacks the part of the brain that regulates hormone production. This causes hypothyroidism which slows the metabolism. (conqueringobesity.com)
Shelgeyr
1 / 5 (1) Jul 20, 2011
Without casting aspersions on this study (it looks like they've probably done a good job), I approach with great wariness any report (results/interpretation) that hints at lessening personal responsibility.

There's a big difference between being tempted, and "being helpless" to give in to temptation.

Like zafouf above, I too am Caucasian, but I'm not as disciplined in my diet as he has apparently been, and therefore have to struggle with my weight. But I'm not willing to blame it on a distant Ice Age or an uncontrollable genetic switch. You know who's to blame?

Me.

I'll admit my genetic heritage may (or may not) have something to do with the appallingly unhealthy foods I crave, but neither my heritage nor anything else other than my will (or lack thereof) is responsible for giving in to those cravings.

The former, unreformed, Cookie Monster was always my childhood hero! You know, prior to his apparent lobotomy...

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