Normally genes change very slowly through mutation. Most mutations are harmful and hence provide no survival advantage to the organism. This is why there is a less than a 2 percent difference between our genes and those of a chimpanzee, even though we became a separate species more than six million years ago. What distinguishes mankind is not the number of genes (corn has twice as many genes as humans), but the speed at which our genes can be turned on and off. This is because of the presence of gene transcription factors that can be activated or inhibited by nutrients. The effect of nutrients on gene expression is known as nutrigenomics.
Because of mankind’s rapid gene switching abilities, gene expression can be influenced significantly by the diet. Due to the speed at which new food ingredients are being introduced into the human diet, these types of nutrigenomic interactions can create radical changes in gene expression in a very short period of time. Normally what a person eats should only affect their gene expression during their lifetime. But is it possible that these changes in genetic expression can be transferred to the next generation?
We can see how genetic engineering (i.e. cross-breeding) can rapidly change the size and shape of dogs, flowers, vegetables and fruits. The genes in each of these species don’t change, but changes in gene expression induced by crossbreeding can persist from one generation to the next, especially if they are constantly reinforced. This is known as epigenetics.
Somehow we don’t think this type of epigenetic change can happen to us, but it does as a result of fetal programming. The prenatal period in the womb is the time that a child’s genes are most susceptible to epigenetic programming. Epigenetic programming can be amplified by the ongoing dietary effects on gene transcription factors (i.e. nutrigenomics) taking place in the mother. The result is the imprinting of epigenetic changes on the genes of the developing fetus that can alter the metabolic future of the child (1).
Examples of how this type of epigenetic programming influences future metabolic effects has been demonstrated under the conditions of famine, which generate increased obesity and cardiovascular disease in the next generation (2). This is also true of children who were exposed to excess calories or elevated levels of glucose while they were developing in the womb (3,4). Likewise hypertension (i.e. pre-eclampsia) during pregnancy increases the risk of stroke as adults if the fetus is exposed to the high blood pressure in the womb (5) as well as the increased risk of adult obesity if the fetus is exposed to gestational diabetes in the mother (6).
Bottom line: The dietary and metabolic environment the fetus is exposed to in the womb can echo through the rest of his or her life.
References:
- Kussman M, Krause L, and Siffert W. “Nutrigenomics: where are we with genetic and epigenic markers for disposition and susceptibility?” Nutrition Rev 68: S38-S47 (2010).
- Painter RC, Roseboom TJ, and Bleker OP. “Prenatal exposure to the Dutch famine and disease in later life.” Reprod Toxicol 20: 345-352 (2005).
- Singhal A. “Early nutrition and long-term cardiovascular health.” Nutrition Rev 64: S44-S49 (2006).
- Boney CM, Verma A, Tucker R, and Bovh BR. “Metabolic syndrome in childhood: associated with birth weight, maternal obesity, and gestational diabetes mellitus.” Pediatrics 115: e290-e296 (2005).
- Kajantie E, Eriksson JG, Osmond C, Thornburg K, and Barker DJP. “Pre-eclampsia is associated with increased risk of stroke in the adult offspring.” Stroke 40: 1176-1180 (2009).
- Lawlor DA, Pichtenstein P, and Langstrom N. “Association of maternal diabetes mellitus in pregnancy with offspring adiposity into early adulthood.” Circulation 123: 258-265 (2011).
- Sears B. “Toxic Fat.” Thomas Nelson. Nashville, TN (2008).
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