Saturated fatty acids can damage cells

Excess saturated fats, such as those released from lard, are toxic to cells and cause a wide variety of lipid-related diseases, while unsaturated fats, such as those from fish and olive oil, can be protective. Researchers developed a new microscopy technique that allows for the direct tracking of fatty acids after they've been absorbed into living cells. The technique involves replacing hydrogen atoms on fatty acids with their isotope, deuterium, without changing their physicochemical properties and behavior like traditional strategies do.

By making the switch, all molecules made from fatty acids can be observed inside living cells by an advanced imaging technique called stimulated Raman scattering (SRS) microscopy.
What the researchers found using this technique could have significant impact on both the understanding and treatment of obesity, diabetes and cardiovascular disease.

The cellular process of building the cell membrane from saturated fatty acids results in patches of hardened membrane in which molecules are "frozen." Under healthy conditions, this membrane should be flexible and the molecules fluidic. The stiff, straight, long chains of saturated fatty acids rigidify the lipid molecules cause them to separate from the rest of the cell's membrane.

Under their microscope, the team observed that those lipid molecules then accumulate in tightly-packed clusters, that don't move much-a state called "solid-like." As more saturated fatty acids enter the cell, those clusters grow in size, creating increasing inelasticity of the membrane and gradually damaging the entire cell.

Lipid molecules made from unsaturated fatty acids bear a kink in their chains, which makes it impossible for these lipid molecules to align closely with each other as saturated ones do. They continue to move around freely rather than forming stationary clusters. In their movement, these molecules can jostle and slide in between the tightly-packed saturated fatty acid chains.
Adding unsaturated fatty acids could 'melt' the membrane clusters frozen by saturated fatty acids, the behavior of saturated fatty acids once they've entered cells contributes to major and often deadly diseases.
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