Reaching the age of 100 has long been considered a remarkable milestone, a rare achievement celebrated in every corner of the globe. A century of life represents not only endurance but also a life rich with experiences, history, and lessons. In earlier times, very few people lived to see their 100th birthday, and reaching this age was often regarded as an extraordinary exception. However, in recent decades, centenarians are no longer as rare as they once were. Advancements in healthcare, improved living conditions, better nutrition, and increased awareness of lifestyle choices have contributed to a noticeable rise in the number of people who surpass this milestone. Despite this, researchers note that centenarians are still not the fastest-growing demographic group worldwide, which suggests that exceptional longevity remains influenced by a complex interplay of factors beyond modern medicine alone.
Recent scientific research has begun to uncover some of these factors, with intriguing findings emerging from studies focused on genetics, lifestyle, and even blood markers. Researchers in Sweden conducted a comprehensive study following tens of thousands of individuals over several decades. They analyzed routine blood tests collected years earlier and explored whether there might be a link between these common markers—and even blood type—and the likelihood of reaching 100 years of age. Could simple lab results, measured when someone was middle-aged or older, hint at who might one day become a centenarian? According to the study, certain routine biomarkers, including glucose, cholesterol, and markers of kidney and liver function, showed patterns that were more common among individuals who lived past 90 or 100. The research, published in a well-respected scientific journal, relied on robust national registers and longitudinal follow-up, making its conclusions particularly reliable. In this overview, we will explore which biomarkers were analyzed, the patterns that emerged, and the implications for our understanding of longevity.
The Study on Blood Markers and Longevity
The primary aim of the Swedish study was to investigate whether blood tests taken years prior could relate to exceptional longevity—defined in this context as living to at least 100 years old. The researchers compared individuals who ultimately reached a century with their peers who did not, ensuring that all participants had their blood drawn at roughly the same age. This is a critical methodological point: comparing a younger person with an older individual can confound any meaningful patterns because age itself dramatically affects lab results. By standardizing the starting age for tests, the study could better identify which markers consistently correlated with longer life.
The markers studied were carefully chosen to reflect key aspects of human physiology, including metabolism, liver and kidney function, iron metabolism, nutritional status, and systemic inflammation. By following participants for up to 35 years using Sweden’s comprehensive national health registers, which record deaths, hospitalizations, and residences, researchers could link early lab results with long-term outcomes. This long follow-up period provides substantial insight into trends that shorter studies might miss.
Importantly, the researchers emphasized that no single lab result guarantees longevity. Instead, the study looked for population-level patterns, estimating the odds of reaching 100 based on where someone fell within the range of each marker. This approach highlights broader trends rather than predicting individual outcomes, offering guidance for public health and clinical practice while avoiding simplistic conclusions.
Participants and Methods
The study utilized the AMORIS cohort, a population-based database derived from clinical laboratory testing in Stockholm County. The cohort initially included over 800,000 individuals, but this particular analysis focused on 44,636 participants born between 1893 and 1920 who had routine blood tests conducted between 1985 and 1996. Follow-up extended from the time of the first blood test until death or the end of 2020. Among these participants, 1,224 ultimately celebrated their 100th birthday, and women comprised about 85% of this group—a reflection of broader survival trends, as women historically outlive men in Sweden and many other countries.
The study linked laboratory results with multiple national registers using Swedish personal identification numbers, allowing precise tracking of diseases and mortality. Statistical analysis included descriptive statistics, logistic regression, and clustering methods to compare distributions, identify patterns, and determine whether centenarians exhibited distinct laboratory profiles. Adjustments for age, sex, and the Charlson Comorbidity Index (which summarizes serious pre-existing conditions) helped isolate the effect of lab values from known health burdens. The long follow-up period, fresh lab samples, and high-quality registry data all strengthened the study’s conclusions, although some lifestyle factors and immune markers were unavailable.
Which Blood Markers Were Examined?
The research analyzed 12 routine blood markers widely used in clinical practice:
Glucose and total cholesterol: indicators of metabolic health.
Creatinine: reflecting kidney function.
Liver enzymes: aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), and lactate dehydrogenase (LD).
Albumin: a marker of nutritional status.
Iron and total iron-binding capacity (TIBC): assessing anemia and iron metabolism.
Uric acid: sometimes linked to inflammation and oxidative stress.
The initial summary of the study suggested that higher cholesterol might correlate with greater odds of reaching 100, but the authors clarified this later. Their corrected guidance noted that low cholesterol was linked with reduced longevity, while high cholesterol neither increased nor decreased the probability of living to 100. The study also revealed a nuanced pattern for many other markers: for instance, being in the highest quintiles of glucose, uric acid, GGT, ALP, LD, and TIBC corresponded to lower odds of exceptional longevity, while very high or very low AST and creatinine levels were also associated with lower odds. This U-shaped pattern illustrates a key principle in medicine: both deficiency and excess can be harmful, and optimal health often lies in moderation.
Glucose: Implications for Longevity
Glucose levels are crucial because chronic hyperglycemia damages blood vessels and nerves over time. In the Swedish study, participants with glucose levels in the highest quintile had lower odds of living to 100. These findings align with decades of research linking elevated glucose to diabetes complications and cardiovascular disease. The American Diabetes Association defines fasting plasma glucose under 100 mg/dL as normal, 100–125 mg/dL as prediabetes, and 126 mg/dL or higher as diabetes. While the study did not diagnose diabetes in all participants, it used quintiles to examine relative risk, reinforcing that maintaining glucose within healthy ranges may support long-term health.
Kidney and Liver Markers
Creatinine, a waste product filtered by the kidneys, provides insight into renal health. Elevated creatinine levels in the top quintiles were linked to lower odds of reaching 100, highlighting the importance of kidney function in longevity. On the liver side, elevated enzymes such as GGT, ALP, and LD similarly correlated with reduced odds, reflecting potential liver stress from disease, medication, or other factors. Aspartate aminotransferase exhibited a U-shaped pattern, with both extremes associated with lower survival probabilities. These markers underscore the role of organ health in supporting a long life.
Uric Acid and Inflammation
Uric acid, a byproduct of purine metabolism, can crystallize in joints and kidneys if elevated, leading to gout or kidney stones. In the study, participants with lower uric acid levels had nearly twice the chance of reaching 100 compared with those in the highest quintile, hinting at the role of systemic inflammation in aging. Low C-reactive protein (CRP) levels, examined in a subset of participants, also correlated with greater longevity, consistent with broader literature linking reduced chronic inflammation to better long-term health.
Overall Takeaways
This comprehensive study of blood markers offers a nuanced view of how routine lab tests can provide insights into longevity trends. While no single number guarantees reaching 100, population-level patterns reveal that extremes—too high or too low—often carry risks. Moderation, organ health, metabolic balance, and low systemic inflammation appear to support exceptional longevity. Importantly, these findings do not replace individualized medical advice; instead, they highlight general targets and areas for attention.
For clinicians and individuals alike, the message is clear: regular monitoring, attention to trends over time, and healthy lifestyle choices—including diet, physical activity, hydration, and stress management—remain foundational for long-term survival. Blood tests may offer a glimpse into the body’s inner environment, but it is the cumulative impact of consistent, healthy habits that often determines whether a person can reach the remarkable milestone of 100 years and beyond.