Why saturated fatty acids are bad for our health

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Using a new technique to visualize the distribution and dynamics of fatty acids within living cells, researchers have discovered why excess saturated fats, such as those released from lard, are toxic to cells and cause a wide variety of diseases. diseases related to lipids.
The study, published in the journal Proceedings of the National Academy of Sciences (PNAS), also showed why unsaturated fats, such as fish and olive oil, can be protective.

The researchers believe that the findings could have a significant impact on the understanding and treatment of obesity, diabetes and cardiovascular disease.

“The behavior of saturated fatty acids once they enter the cells contributes to the main, often deadly, diseases,” said study lead researcher Wei Min, a professor at Columbia University in New York.

“Visualizing how fatty acids contribute to the metabolic disease of lipids gives us the direct physical information we need to begin to look for effective ways to treat them – perhaps, for example, we can find a way to block the toxic accumulation of lipids.” added Min.

The researchers developed a new microscopy technique that allows direct monitoring of fatty acids after they have been absorbed by living cells.

The technique involves replacing the hydrogen atoms in the fatty acids with their isotope, deuterium, without changing their physicochemical properties and behavior, as traditional strategies do.

By making the change, all the molecules made of fatty acids can be observed inside the living cells by means of an advanced imaging technique called stimulated Raman scattering microscopy (SRS).

The researchers found that the cellular process of building the cell membrane from saturated fatty acids produces patches of hardened membrane in which the molecules are “frozen”.

In healthy conditions, this membrane must be flexible and fluidic molecules.

The researchers explained that the rigid, straight, long chains of saturated fatty acids stiffen the lipid molecules and cause them to separate from the rest of the cell membrane.
Under their microscope, the team observed that these lipid molecules accumulate in “islands”, or clusters, that do not move too much, a state they call “solid”.

As more saturated fatty acids enter the cell, those islands grow in size, creating an increasing inelasticity of the membrane and gradually damaging the entire cell.

“We found that adding unsaturated fatty acids could ‘melt’ the islands of the membrane frozen by saturated fatty acids,” said first author Yihui Shen, a graduate student in Min’s laboratory.

This new mechanism, he said, may partly explain the beneficial effect of unsaturated fatty acids and how unsaturated fats such as fish oil may be protective in some lipid disorders.