Whole-fat vs. reduced-fat milk: Which is better for our cells?

Healthy Aging

Moving to reduced-fat milk negatively impacts red blood cells

In this series, we are catching up on the latest peer-reviewed C15:0 science that has been published during 2023.

This week, let’s talk about a new abstract published in Proceedings of the Nutrition Society, which studied how moving from whole-fat to reduced-fat dairy products affects children’s red blood cells.

Toddlers are often moved from whole-fat to reduced-fat milk.

The American Academy of Pediatrics currently recommends that parents move their kiddos, once they turn 2 years old, from whole-fat milk to low or non-fat cow’s milk. As such, Nicholl et al conducted what they called the Milky Way Study, to look at the effects of moving 49 kids (4 to 6-year olds) from whole-fat to reduced-fat dairy products for 3 months. Specifically, they wanted to find out if this dietary change affected the fatty acid profile of their red blood cells.

So, why did they look at fatty acids in red blood cells?

Well, the fatty acid content of our red blood cell membranes provides a super helpful window into the fatty acid content of cells throughout our body. Red blood cell fatty acid measurements readily reflect how a dietary change impacts our cell membrane makeup.

Got it. What did they find?

Nicholl et al. showed that when kids moved from whole-fat to reduced-fat dairy products, C15:0 (pentadecanoic acid) levels in their red blood cell membranes declined. Interestingly, they also showed that omega-3 fatty acid levels decreased, too.

The authors concluded that moving kids from whole-fat to reduced-fat dairy products was detrimental to the fatty acid composition of red blood cells.

But, why are these changes detrimental?

While Nicholl et al. focused on the detriment of lower omega-3s, there are a few reasons why decreased C15:0 content in our cell membranes can be more detrimental.

• First, cellular instability. C15:0 is a stable fatty acid that is particularly resistant to lipid peroxidation and keeps our cell membranes strong. Decreased C15:0 content in cell membranes makes red blood cells more fragile and more susceptible to lipid peroxidation.
• Second, anemia. Specific to red blood cells, Soboleva et al. showed that kids with fragile red blood cells (aka anemia) have high overall levels of lipid peroxidation. And those who had the lowest C15:0 in their red blood cells, had the most fragile cells and highest levels of lipid peroxidation. In contrast, the more polyunsaturated fatty acids (aka omega-3s) the kids had, the more fragile their cells.
• Third, a theory on shorter longevity. This phenomenon of fragility is not limited to red blood cells. As described in A.J. Hulbert’s Cell Membrane Pacemaker Theory of Aging, the more stable the fatty acids in all of our cell membranes, the longer a mammalian species lives. Yep – stronger cell membranes explain how we live longer than our fellow mammalian mice.