More and more people in the UK are living to 100.  Why is this? Is it down to lifestyle choices, to our genes or to something else?  

Is it all in our genes?

Studies have shown that exceptional longevity (reaching 100+) is linked to a particular gene, apolipoprotein E (ApoE). This is a protein that transports fats, such as cholesterol and triglycerides, around our body. Our bodies need both cholesterol and trigylcerides to function normally, but too much of either increases the risk of heart attack and stroke. In addition, several specific variations in additional genes have been identified in a 2020 pooled analysis of data. The majority of 10 gene variations found to influence healthspan (years lived in good health), lifespan (total years lived) and longevity (survival to an exceptional old age) were associated with cardiovascular disease. 

Large scale centenarian research in the US concludes, ‘Genes play a critical and complex role in facilitating exceptional longevity. The genetic influence becomes greater and greater with older and older ages, especially beyond 90-99 years of age.’ However, centenarians (with rare exceptions) have just as many genetic variants associated with increased risk for age-related diseases (e.g. Alzheimer’s, stroke, cancer) as people in the general population. This suggests that they live so long, in part, because the gene variants associated with longevity are protective against the effects of the disease-related genes. 

Interestingly, the specific combinations of gene variants expressed by subgroups of centenarians (called genetic signatures) are associated with different disease predispositions such as escaping heart disease or delaying the onset of Alzheimer’s until near the end of their long lives. These findings suggest that different combinations of a variety of gene variants contribute to living a long life, partly via their protective effects on disease-related genes.

Does epigenetics play a role? 

Epigenetics is the study of how your behaviours (e.g. diet, exercise) and the environment can cause changes that affect the way your genes work. Unlike changes to your genes, epigenetic changes are reversible.

Our genes can sometimes be switched on, switched off or modified by epigenetic factors. Factors such as maternal diet, stress hormones, and microbiota (microorganisms including bacteria and viruses) in the gut during pregnancy can affect foetal development and may influence how long we live in good health, even if it may not be enough to help us live to 100. 

In addition, your epigenetics change throughout your life as you develop and age, and because of exposure to environmental factors.

Does gender matter?

Recent research shows that the gap between men and women’s longevity has declined due to improvements in mortality for men. Now, fewer than 5 women for every man reaches 100, down from 8 women to every man in 2002– according to updated statistics from Office of National Statistics.  

Reports have also shown that women who give birth to their last child at a higher age live longer. It is thought that having a child later in life is a sign of both good reproductive health and overall health supporting longevity. 

What about a healthy lifestyle?

In addition to the contribution of genes (20-40%), a healthy lifestyle appears to add substantially to the longevity of centenarians

A healthy lifestyle includes five key components:

1. A healthy diet
2. Physical activity
3. Healthy body weight
4. No smoking
5. Moderate alcohol intake

There is strong evidence that both diet and lifestyle changes contribute to living longer and reaching centenarian status.  

• Low intensity physical exercise, including walking, can exert anti-ageing effects and helps prevent age-related diseases.
  Walking has been shown to contribute significantly to longevity, alongside a mainly vegetarian diet, strong social networks, avoiding smoking and having a sense of purpose.
• In recent times centenarians have even begun to participate in sporting competitions worldwide, becoming icons of healthy ageing and providing evidence that you are never too old to exercise, as regular exercise may combat the deleterious effects of ageing. 
• Few centenarians appear to be obese. The findings of a study of 253 Chinese centenarians showed that they appeared to have a lower waist circumference and body mass index (BMI) than elderly controls. However, they had a higher prevalence of hypertension (high blood pressure). 
• Other research in China suggests that proximity to more green space is associated with increased longevity. This may be because it encourages exercise, is good for mental health and reduces exposure to air pollution.
• There is increasing evidence that the microorganisms in the gut (gut microbiome) are important for human health and are modified by diet. A 2024 study has shown that the gut microbiome of long-lived individuals differs from those of younger elderly and young adults. The microbial signatures present in these individuals were shown to have a potentially causal relationship with longevity and ageing. 

What other factors contribute to a long life? 

• Social contacts
  Data from a longitudinal study of 5,700 Chinese individuals has shown that those with the least social isolation had higher odds of becoming centenarians compared to those with a higher social isolation score. Since research has linked social isolation and loneliness to higher risks for a variety of physical and mental conditions such as high blood pressure, heart disease and Alzheimer’s Disease, this suggests that keeping up social contacts contributes to longevity.
  
• Coping skills and positive attitudes
  Although frailty is common among centenarians, another study conducted in the state of Georgia, US has shown that the oldest-old develop coping skills and positive attitudes that give them a satisfaction with life and which supports their mental health.
• Resilience
  Centenarians also appear to be more resilient than those who don’t live as long and have an increased capacity to respond to the minor stresses of daily life.
• Conscientiousness There is increasing evidence that conscientious people tend to live longer. Conscientiousness has been linked to health-related behaviours such as risk-taking, and to immune function which may help to explain its association with longevity. 

Conclusions 

You can’t do much about the genes you inherit or your gender, two key factors when it comes to living to 100 and beyond.

However, you can increase your chances of living longer in good health through:

• A healthy lifestyle (not smoking, physical activity and a healthy diet)
• A positive approach to life, being conscientious and managing stress
• Building and maintaining social networks 

Reviewed and updated by Barbara Baker, November 2024.
Next Review Date October 2028.