Longevity Briefs: Can Zinc Delay The Ageing Process?

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

The problem:

We’re living longer than ever before, but this increased lifespan doesn’t always translate to a healthier one. Modern medicine may have significantly extended human lifespan, but many people are living out those additional years of life with debilitating age-related diseases. We know that people undergo biological ageing (as opposed to chronological ageing, the time passed since birth) at different rates, and hence can develop age-related diseases much earlier or later than average. Slowing down the ageing process by even a small amount could have significant implications for human health, by delaying the onset of all age-related diseases and allowing people to live healthy lives for longer.

There is no definitive way to measure how quickly someone is ageing, but there are a growing number of increasingly sophisticated methods for estimating biological age. This allows scientists to test various treatments to see if they might slow the ageing process. In this study, scientists use one such method to assess the effects of zinc. Zinc is often touted for its various health benefits, from its effects on immune function to cognitive health, but the relationship between zinc and biological age remained unclear. Another unknown is the relationship between health, exercise and zinc intake.

The discovery:

Researchers conducted a study using data from the UK Biobank, a large database containing health information from hundreds of thousands of UK adults. They focused on 68,947 adult participants for which there was data on zinc intake. This intake was determined from participants’ reported food consumption and supplement use. They also measured physical activity levels and estimated participants’ biological age using an algorithm called ENABL Age. This is a relatively new tool that takes data from various blood markers, uses them to predict age-related health outcomes and then converts these predictions into a biological age estimate. This approach makes ENABL Age better at separating healthy ageing form unhealthy ageing, compared to some older methods.

After adjusting for confounding factors like exercise, age and income, people who met the recommended zinc intake (11 milligrams per day for men and at least 8 mg per day for women) were, on average, estimated to be biologically younger by 0.13 years compared to those who did not – a small but statistically significant reduction. Being over the maximum recommended intake of 40 milligrams per day was associated with accelerated biological ageing of around 3.23 years.

Combining physical exercise with zinc was associated with greater benefits. As a baseline for comparison, researchers used participants not meeting the zinc recommendations and doing less than 600 metabolic equivalents of task (METs) per week. This is roughly equivalent to 150 minutes of moderate exercise or 75 minutes of high intensity exercise per week. Compared to these people, those who only achieved 600 METs per week and those meeting only the zinc recommendations saw their likelihood of experiencing accelerated ageing decrease by 19% and 16%, respectively. Those who met both requirements, on the other hand, saw a 31% reduction.

The implications:

This research suggests that zinc, like many other nutrients, is a double-edged sword. While a moderate amount can be beneficial, excessive intake can be detrimental to our health and potentially accelerate ageing. How? The researchers offer several potential mechanisms. Short term overdoses of zinc are toxic and could lead to disruptions in fat metabolism, while long-term overdoses could negatively impact iron distribution and impair immune function. However, it is important to note that estimates of dietary intake from self-reported data are quite inaccurate, not only because people misreport their intake, but also because estimates of zinc content within different foods can be incorrect. Furthermore, intake of zinc is associated with the intake of other nutrients that may also have an impact on biological ageing. For these reasons, it’s impossible to conclude from this study that either effect on biological age was actually caused by zinc.

On the assumption that zinc was responsible for these effects, the benefits of combining zinc with exercise was roughly what one might expect based on their independent benefits. So, while exercise and zinc may not be synergistic (the combined effect is not greater than the sum of their parts), the apparent benefits of zinc don’t seem to be dependent on exercise. The take-home message is that reaching the recommended zinc intake through diet (with additional supplements if necessary) could slightly slow biological ageing, but care should be taken not to exceed 40mg/day.