A reading of 115/57 mmHg puts you in an interesting gray zone. The top number, 115, is solidly in the normal range and is actually close to what most guidelines consider optimal for cardiovascular health. The bottom number, 57, falls below 60 mmHg, a threshold that has drawn increasing attention from researchers studying heart and brain health. Whether this reading is “good” or “too low” depends heavily on who you are, what symptoms you have, and whether you carry certain preexisting conditions.
What the Two Numbers Tell You Separately
Blood pressure readings contain two distinct pieces of information. The systolic pressure (top number) reflects the force your heart generates when it contracts. The diastolic pressure (bottom number) reflects the pressure in your arteries between heartbeats, when the heart is refilling with blood. These two numbers do not always move in lockstep. It is entirely possible to have a healthy systolic reading paired with an unusually low diastolic reading, or vice versa.
At 115, your systolic pressure sits comfortably below the 120 mmHg upper boundary of what is classified as normal. Most major guidelines agree that a systolic reading in the 90 to 119 range is healthy, so there is nothing concerning about that number in isolation. The diastolic reading of 57, though, sits below 60, which is the threshold several large studies have identified as a potential risk marker. That does not mean 57 is automatically dangerous, but it does mean it deserves a closer look.
The Diastolic Below 60 Question
Diastolic pressure matters because it reflects the baseline pressure your arteries maintain between heartbeats. Your coronary arteries, the ones feeding the heart muscle itself, receive most of their blood supply during this resting phase. When diastolic pressure drops too low, the concern is that the heart muscle might not get adequate blood flow, especially if the arteries are already partially narrowed.
A large community-based study called the Multi-Ethnic Study of Atherosclerosis found that people with a diastolic blood pressure below 60 mmHg had a roughly 70% higher risk of coronary heart disease events and about a 48% higher risk of dying from any cause compared to those with diastolic pressures in the 80 to 89 range. Crucially, the increased risk was strongest in people who already had subclinical atherosclerosis, meaning some buildup in their arteries even without symptoms.1PubMed Central. Relation of Diastolic Blood Pressure and Coronary Artery Calcium to Coronary Events and Outcomes (From the Multi-Ethnic Study of Atherosclerosis) A separate study in patients with stabilized heart failure found that those who experienced even a single episode of diastolic pressure below 60 had higher rates of heart failure rehospitalization compared to those who stayed above that level.2The American Journal of Medicine. Prognostic Value of Transient Diastolic Hypotension in Stabilized Heart Failure
These findings are striking, but they come with a critical caveat: most of the elevated risk concentrates in people who already have heart disease, artery buildup, or other cardiovascular conditions. A 30-year-old with clean arteries and no symptoms is in a fundamentally different situation than a 70-year-old with known coronary disease.
When a Low Diastolic Is Perfectly Normal
Plenty of healthy people walk around with diastolic pressures in the mid-to-upper 50s without any ill effects. Endurance athletes are a classic example. Training causes the heart to become more efficient and blood vessels to become more compliant, which naturally lowers resting diastolic pressure. A study comparing young endurance athletes, non-endurance athletes, and non-athletes confirmed that diastolic blood pressure was significantly lower in both athlete groups compared to non-athletes.3PubMed Central. Resting Electrocardiogram and Blood Pressure in Young Endurance and Nonendurance Athletes and Nonathletes These lower readings reflect cardiovascular fitness, not disease.
Sex plays a role too. Women, particularly younger women, tend to have lower blood pressures than men. One study of university students found that men had diastolic pressures about 3.6 mmHg higher on average than women, and the difference in systolic pressures was even larger.4PubMed Central. Blood Pressure and Its Association with Gender, Body Mass Index, Smoking, and Family History among University Students A reading of 115/57 in a physically active young woman is almost unremarkable. That same reading in a 65-year-old man on blood pressure medication tells a different story.
Pregnancy also reshapes blood pressure patterns. During the second trimester, diastolic pressure typically dips as blood vessels relax to accommodate increased blood volume. A temporary diastolic reading in the mid-50s during pregnancy can be entirely physiological.
The J-Curve and Why It Matters for Your Heart
Researchers have long observed something called the J-curve in blood pressure data. The name comes from the shape of the graph: as diastolic pressure drops from high to moderate, cardiovascular risk drops too. But at some point, the curve bends back upward, meaning very low diastolic pressure starts to be associated with increased risk again. This upswing tends to appear once diastolic pressure falls below roughly 70 to 80 mmHg, depending on the population studied.5PubMed Central. The significance of the j-curve in hypertension and coronary artery diseases
The most widely accepted explanation for the J-curve centers on coronary blood flow. The coronary arteries fill primarily during the resting phase of the heartbeat, when diastolic pressure is what drives blood through them. In people with significant narrowing of these arteries, the remaining reserve for blood flow is already thin. Drop the diastolic pressure too far and you can push that reserve below what the heart muscle needs, particularly during moments of increased demand like exercise or stress.6PubMed Central. Coronary flow reserve and the J curve relation between diastolic blood pressure and myocardial infarction
For someone without coronary artery disease, the J-curve effect is far less pronounced. A study of older patients with isolated systolic hypertension (high top number, normal or low bottom number) found that lowering diastolic pressure with medication, even down to about 55 mmHg, did not increase cardiovascular death in patients without a history of coronary disease. In patients who did have a history of coronary disease, however, low on-treatment diastolic pressures were associated with increased cardiovascular events.7JAMA Internal Medicine. On-Treatment Diastolic Blood Pressure and Prognosis in Systolic Hypertension The takeaway is that your coronary artery health is probably the single biggest factor in determining whether a diastolic reading of 57 is benign or worrisome.
Your Pulse Pressure Is Worth Checking
The gap between your systolic and diastolic numbers is called pulse pressure. With a reading of 115/57, your pulse pressure is 58 mmHg. Normal pulse pressure at rest is generally considered to be around 40 mmHg, so 58 is wider than average. A wide pulse pressure can reflect stiffening of the large arteries, which forces the systolic number higher while the diastolic number stays put or drops. In younger people, it can also just reflect strong cardiac output with compliant arteries, which is not a problem.
Where pulse pressure gets more relevant is in older adults and people with chronic conditions. Research has identified wide pulse pressure as an independent risk factor for cardiovascular events, progression of kidney disease, and mortality, separate from what either systolic or diastolic pressure predicts on its own.8PubMed Central. Wide pulse pressure: A clinical review Most standard blood pressure guidelines focus on the systolic and diastolic numbers individually, which means a concerning pulse pressure can slip under the radar if nobody calculates it. At 58, your pulse pressure is mildly elevated but not alarming on its own. It is worth mentioning to your doctor, especially if it consistently shows up at that level across multiple readings.
Medication-Driven Low Diastolic Pressure
If you take blood pressure medication, a diastolic of 57 raises a specific question: is the drug pushing your bottom number too low while targeting the top number? This is a common scenario in isolated systolic hypertension, where the systolic number is the problem but medications lower both numbers together. Doctors have debated for years whether the low diastolic pressure that results is harmful or merely a harmless byproduct of necessary treatment.
A post-hoc analysis of the SPRINT trial, one of the largest blood pressure treatment trials ever conducted, found that while people with the lowest on-treatment diastolic pressures had higher raw event rates, those differences disappeared after adjusting for age, kidney function, and other health factors. The researchers concluded that low diastolic pressure achieved during treatment should not be a major concern in itself.9PubMed Central. Low on-treatment diastolic blood pressure and cardiovascular outcome: A post-hoc analysis using NHLBI SPRINT Research Materials A separate analysis from the ESPRIT trial similarly found that low diastolic pressure from blood pressure treatment did not increase stroke risk.10European Heart Journal. Low on-treatment diastolic blood pressure, pulse pressure, and mean arterial pressure does not increase risk of stroke: a post-hoc analysis of the ESPRIT trial
These findings offer some reassurance, but they do not close the case entirely. The patients who tend to develop very low diastolic pressures on medication are often older, have stiffer arteries, and carry more comorbidities, all of which independently raise risk. The data suggest that simply having a low diastolic number while on treatment is not, by itself, the problem. But it may be a signal that the person is in a higher-risk group for other reasons, and clinicians should investigate rather than just change the drug dose reflexively.
What Low Diastolic Pressure Means for Your Brain
The brain, like the heart, depends on adequate blood pressure to stay well-perfused. Some research has linked chronically low diastolic blood pressure to cognitive decline, especially in older adults. A longitudinal study of elderly Korean participants found that those with diastolic pressures below about 80 mmHg showed greater declines on memory and constructional thinking tests over a two-year follow-up compared to those with higher readings.11PubMed Central. Low Diastolic Blood Pressure and Cognitive Decline in Korean Elderly People: The Korean Longitudinal Study on Cognitive Aging and Dementia A broader review of the evidence noted that low diastolic pressure, alongside very high systolic pressure, may increase the risk of cognitive impairment and dementia in later life.12PubMed Central. Relation of Blood Pressure to Cognitive Impairment and Dementia
One proposed mechanism is that reduced diastolic pressure lowers cerebral perfusion, the steady flow of blood that keeps brain cells alive and functioning. In older adults whose brain arteries may already be narrowed or stiffened, even a modest drop in perfusion pressure could accelerate damage over time. Some researchers have suggested that in advanced age, reduced cerebral blood flow tied to low blood pressure may play a role in the development of Alzheimer’s disease.13JAMA Neurology. Low Blood Pressure and Risk of Dementia in the Kungsholmen Project: A 6-Year Follow-up Study
For younger adults, this is much less of a concern. The brain’s ability to regulate its own blood flow, called autoregulation, is robust in healthy people and compensates effectively for lower blood pressures. The cognitive risks linked to low diastolic pressure appear to be largely a phenomenon of aging, particularly in people whose blood vessels have already lost some of their flexibility.
Your Kidneys Care About Diastolic Pressure Too
The kidneys are another organ that depends on adequate diastolic perfusion. A study of patients being treated for hypertension found that 24-hour diastolic blood pressure values at or below 70 mmHg were associated with decreased kidney filtration rates. The relationship was specific to diastolic pressure and not observed with systolic values.14PubMed Central. Association between 24-hour diastolic blood pressure and renal function in patients receiving treatment for essential hypertension At 57, your diastolic reading sits well below that 70 mmHg mark, which could be relevant if you already have any degree of kidney impairment.
Again, context is everything. A healthy kidney with intact filtration capacity can handle lower perfusion pressures without trouble. The concern intensifies in people who already have some kidney disease, diabetes, or other conditions that compromise renal blood flow. If your kidney function tests are normal, a diastolic of 57 is unlikely to be causing kidney problems. If you have known kidney issues, it is worth discussing with your doctor whether your blood pressure management is inadvertently putting extra strain on kidney function.
One Reading Versus a Pattern
Blood pressure is not a fixed number. It fluctuates throughout the day based on activity, posture, hydration, stress, caffeine intake, and even time of day. A single office reading of 115/57 is a snapshot, not a diagnosis. In a large international database of ambulatory blood pressure monitoring, the average diastolic pressure dropped by about 14 mmHg from daytime to nighttime in both normotensive and hypertensive individuals.15PubMed. Nocturnal blood pressure fall on ambulatory monitoring in a large international database That means if your reading was taken during a relaxed state or later in the day, it could easily be several points lower than your usual daytime average.
White coat effects (higher readings in a clinical setting) and masked hypertension (normal readings in the office but elevated at home) are well-documented patterns.16PubMed Central. Patterns of ambulatory blood pressure: clinical relevance and application The reverse can happen too: some people run lower in the office due to deliberate relaxation. If 115/57 was a one-time reading, taking multiple readings at home over a week or two will give you a much more reliable picture. If the diastolic consistently falls below 60, that pattern deserves attention. If it was a single low reading among many in the mid-60s or higher, it is probably meaningless.
Symptoms That Should Prompt a Visit
Numbers alone do not determine whether your blood pressure is “too low.” Symptoms matter just as much. Plenty of people function perfectly well with diastolic pressures in the 50s. If you feel fine, have no dizziness, no lightheadedness when standing up, no unusual fatigue, and no episodes of feeling faint, then 115/57 is likely your normal and nothing to worry about.
The symptoms that should prompt medical evaluation with a blood pressure in this range include:
- Orthostatic dizziness: feeling lightheaded or seeing spots when you stand up from sitting or lying down
- Persistent fatigue: feeling unusually drained even with adequate sleep, especially if this is a change from your baseline
- Fainting or near-fainting: even a single episode warrants evaluation
- Chest discomfort or shortness of breath: could indicate that the heart is not getting enough blood during its resting phase
- Difficulty concentrating: persistent mental fog that worsens over time, particularly in older adults
If any of these symptoms accompany your reading, your doctor will likely want to investigate further. They may check for dehydration, anemia, thyroid problems, adrenal insufficiency, or cardiac conditions that could be driving the low diastolic. If you are on blood pressure medication, they may adjust the dose or switch to a drug that has less impact on the diastolic number.
How Diet and Hydration Affect the Bottom Number
Dehydration can lower blood pressure across both numbers, and some people who see unexpectedly low readings simply are not drinking enough fluids. Salt intake is another lever. In people being treated for hypertension, adopting a “no added salt” diet lowered both systolic and diastolic pressures significantly, with diastolic drops averaging about 7 mmHg during the day.17PubMed Central. Effect of “no added salt diet” on blood pressure control and 24 hour urinary sodium excretion in mild to moderate hypertension If your blood pressure is already low and you are eating a very low-sodium diet, it is worth considering whether your dietary habits are contributing.
Alcohol can also acutely lower blood pressure, as can certain supplements like magnesium and high-dose omega-3 fatty acids. If you recently changed your diet, started a new supplement, or increased your exercise intensity, any of these could explain a diastolic reading that has drifted lower than usual. There is nothing inherently wrong with a reading of 57 if it reflects healthy choices and you feel well. The concern kicks in when low diastolic pressure is unexplained or accompanied by symptoms.
Age-Related Widening of the Gap
One pattern worth understanding is that as people age, systolic pressure tends to rise while diastolic pressure tends to fall. This divergence happens because large arteries stiffen with age, losing their ability to stretch and recoil smoothly. The stiffened arteries create higher peak pressures during each heartbeat (driving systolic up) but cannot maintain pressure between beats (allowing diastolic to drift down). The result is a gradually widening pulse pressure.
In someone over 60 or 65, a reading of 115/57 might actually represent this age-related pattern. The systolic of 115 looks normal, but it might be lower than expected because of medication, while the 57 diastolic reflects stiff arteries that can no longer hold pressure between beats. In this context, the pulse pressure of 58 takes on added significance as a possible marker of arterial stiffness. In a younger person with elastic arteries, the same numbers usually reflect strong cardiac output and healthy vasculature instead.
This is one reason why identical blood pressure numbers can mean very different things in different people. A 25-year-old runner and a 72-year-old on two blood pressure medications can both produce a reading of 115/57, but the clinical meaning is worlds apart. The number itself is not the answer; the person behind the number is.