You are what you eat 
(we’re talking to you, cells)

Healthy Aging

Fats in our diet determine the strength of our cells

In this series, we are covering the science behind our cell membranes – because they (literally) cover our cells, our health, and even our longevity.

This week, let’s talk about how different fats in our diet determine the strength or weakness of our cells.

What would you choose?

If you had to choose between bricks or rubber bands to build your house, which would you choose? Taking a leap of faith here, but guessing you answered bricks. That is because sturdy walls and a roof protect you from damaging outer elements (these days, the sun and heat).

The same is true of our cell membranes. The sturdier our cell membranes, the better they protect our cells against damaging oxidation, chronic inflammation, and aging-related breakdown. Here’s the good news: What we eat directly determines the sturdiness of our cells, and it’s all about the fat.

Unsaturated vs. saturated fats.

Time to dust off your chemistry hats. In order to understand how different types of fats affect the strength of our cell membranes, we need to understand the difference between unsaturated and saturated fatty acids:

• Unsaturated fatty acids (like omega-3s) have double bonds in their structure. Poly-unsaturated fatty acids have multiple double bonds. Every added double bond in a fatty acid serves as a weak and unstable point that increases that fatty acid’s susceptibility to oxidation. This is why unsaturated fatty acids are oils at room temperature and are easily oxidized, resulting in rancidity.
• In contrast, saturated fatty acids (like C15:0) have no double bonds, which make them solid at room temperature and highly resistant to oxidation.

A measurement often used to indicate the amount of saturated vs. unsaturated fatty acids is called the saturation index.

A lesson from chipmunks.

Back in 1990, Fritz Geiser showed that chipmunks fed sunflower seed oil (an unsaturated fat diet) have cell membranes with a lot more unstable fatty acids. In contrast, chipmunks fed sheep fat (a saturated fat diet) have cell membranes with way more stable fatty acids. Thus, Fritz showed that fats in the diet directly determine fatty acids in cell membranes… at least in hibernating nut hoarders.

Yeah, we’re like chipmunks.

Over a decade later, Murray et al. showed the same outcomes with humans. In this study, people were initially given a high saturated fat diet and then moved to a high polyunsaturated fat diet. He found that people’s cell membrane fatty acids followed their dietary change – within 5 days after moving onto the new diet. Specifically, Murray et al. reported that participants’ C15:0 plasma and cell membrane levels dropped significantly within 2 to 5 days after moving off a high saturated fat diet, while their polyunsaturated fatty acid levels increased.

Here’s what happens to cell membrane C15:0 levels when people moved from a high-C15:0 diet to a high polyunsaturated fatty acid diet: