FABP2, a gene that appears in both the carbohydrate and saturated fat parts of our reports. This gene creates a protein called Fatty Acid Binding Protein-2, which is found in our small intestines. FABP2 binds to the various different fatty acids, and allows them to be absorbed into the body.
The single nucleotide polymorphism (SNP) that we are interested in occurs when an alanine nucleotide is swapped for a threonine nucleotide; this substitution causes the protein to become more efficient. So efficient, in fact, that it doubles the speed at which we absorb these fats, leading to an increase of fat in the blood stream.
So what effect does this have in the real world? One study, published in 2007 in the American Journal of Clinical Nutrition gives us some idea. The researchers got 122 elderly adults, and put them through a number of different tests to see how they tolerated different types of foods. Those with at least one A allele of FABP2 were less likely to have normal blood glucose levels, both after fasting and after having a big meal. This indicates that they were at risk of developing insulin resistance, which can eventually become type-II diabetes. If we know that A allele carriers are more likely to develop type-II diabetes, then we can give them dietary advice which might help to reduce their risk, such as consuming a diet lower in simple and refined carbohydrates.
We’ve looked at the effects of FABP2 on our carbohydrate sensitivity, but how about saturated fats? A meta-analysis published in 2010 gives us an insight into this. Meta-analyses are useful tools for researchers and medical professionals, as they analyse the data of existing research in a particular area, and summarise it to give us a better idea of the current evidence in that field. The results from this meta-analysis looked at 30 different studies, with over 14,000 subjects. It found that A-allele carriers of FABP2 were significantly more likely to have higher concentrations of total- and LDL-cholesterol (LDL cholesterol is commonly known as “bad” cholesterol), and lower levels of HDL-cholesterol (“good” cholesterol) – showing quite nicely that this gene influences how much fat we should have in our diet.
We use FABP2 alongside a number of other genes to give each person an idea of their individual response to both carbohydrates and fats, information that we can then use to determine the optimal diet type for weight management. The below table summarises the main findings regarding FABP2:
|GG||This genotype is not associated with an increased sensitivity to saturated fats or refined carbohydrates.|
|GA||A single copy of the A allele is associated with a moderately increased sensitivity to saturated fats and refined carbohydrates.|
|AA||Two copies of the A allele of FABP2 means that this genotype is associated with a significantly increased sensitivity to both saturated fats and refined carbohydrates.|