Why do people age differently?

Key points:

• Researchers continue to find out more about the role lipids play in the ageing process

• There are four types of lipids in the human body: fatty acids — saturated and unsaturated; glycerides — glycerol-containing lipids; nonglyceride lipids — sphingolipids, steroids and waxes; complex lipids — lipoproteins and glycolipids

• Research findings suggest serum lipids increase with age until puberty and decline thereafter

This edition of the Aged Care Guide looks at the role lipidome plays in the ageing process, along with age-related conditions, such as type-two diabetes and Alzheimer’s disease. In this guide, readers will be treated to new research that gives senior Australians insight into how some people age better than others and how a person’s body may change over time.

What are lipids?

‘Lipids’ are the fats that are consumed and stored in the human body or created and secreted. When a person is tested for cardiovascular or age-related diseases, such as type-two diabetes, a medical expert may request a lipid profile, which looks at an individual’s cholesterol and triglyceride levels.

In the human body, lipids make up cell membranes, act as cellular messengers and store energy; they play key roles in responding to infection and regulating a person’s metabolism.

Your lipidome, which is the term for all of the lipids in your body, can be directly altered, in part, by what you eat and which microbes live inside your gut — making it more malleable and possibly more responsive to interventions. However, the number and variety of lipid molecules — of which there are thousands — have made them hard to study.

So, what does this have to do with ageing?

Stanford University researchers assessed more than 100 participants in a study about lipidome and respective health indicators, with many participants at risk of diabetes, over the course of nine years.

Using mass spectrometry techniques, which separate compounds by their molecular mass and electric charge, researchers catalogued approximately 800 lipids and their associations with insulin resistance, viral infection, ageing and more. 

The researchers found that although everyone’s lipidome has a distinctive signature that remains stable over time, certain types of lipids change predictably with a person’s health.

“Lipids are very understudied,” said Stanford University geneticist Michael Snyder.

“They are involved in pretty much everything, but because they’re so heterogeneous and there are so many of them, we probably don’t know what most lipids really do.”

The participants, aged 20 to 79 years, and the length of the nine-year study allowed researchers to see how the lipidome changes with age. The recent study, published in Nature Metabolism, found that most lipids, such as cholesterol, increase with age, but a few — including omega-three fatty acids, which are known for their health benefits — decrease.

According to Si Wu, PhD, the co-lead author of the study, these signs of ageing in the lipidome do not occur at the same rate in everyone — insulin resistance, for example, seems to accelerate them.

“It raises the interesting question of whether lipid profiles could predict whether an individual is biologically ageing more quickly or more slowly,” Wu said.

Another surprising insight, Wu said, was how consistently certain groups of lipids, such as ether-linked phosphatidylethanolamines — which are thought to be antioxidants and involved in cell signalling — were associated with better health.

Have you heard of lipids before or have you been tested for heart disease? Let us know your thoughts on social media. 

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