A blood pressure around about 120/80 is pretty well perfect. Blood pressure such as 110/60, or lower, may contribute to poor concentration, feeling light headed upon standing up and feeling excessively tired at times. Pressures that persistently exceed 140/90 will be detrimental to health over time.
The trend of advice from heart experts is to progressively lower the bar as to what is ideal BP. Advice varies; but the current trend is to recommend a blood pressure of about 110/70 to 100/60. I am inclined to disagree. 100/60 is too low and indicates poor health. Health advice that is geared towards preventing a singular disease, such as heart attack, can cause more problems down the line because human beings are exceedingly complex creatures. Anything less than a holistic approach will not improve overall health.
There is plenty of evidence that the lower the BP, the lower the risk of heart attack; but there is the downside of low blood pressure causing, or making worse, conditions like muddled thinking, excessive fatigue and dizziness. These can have a profound negative effect on a person's quality of life; especially in old age. Low blood pressure, including medications to lower blood pressure, increase the chances that an elderly person will be involved in car accidents and injury by falling.
So, an elderly lady on blood pressure medication may be less likely to die of a heart attack. This is good for the heart disease statistics. Instead, she has a dizzy spell, trips, breaks a hip and then dies slowly and miserably of pneumonia.
Be wary of single issue health advice. It may actually be hazardous to your health!