Ask Dr.  Grossman
Dr. William Grossman, Co-Director, UCSF Center for Prevention of Heart and Vascular Disease, answers some frequently asked questions.

A PATIENT ASKS: “Do GI microbes affect heart health? If so, is there a healthy strategy to follow? And what about unfiltered apple cider vinegar?”


This question touches on some cutting-edge research. Our intestines contain some 1,000 distinct species of bacteria, each species numbering in the millions of bacteria. This gut microbiome is believed to play an important role in cardiovascular health, primarily by producing key nutrients needed for cardioprotection. As I mentioned in a previous HeartLine article, researchers eliminated all intestinal bacteria in mice, which then became progressively ill and showed signs of cardiovascular disease.

Based on this and other research studies over the years, many companies market “probiotics.” Some of my patients take a probiotic, supposedly a collection of normal intestinal bacteria, to replenish their own gut microbiome. This is another good reason not to take antibiotics for minor flu symptoms or other illnesses unless truly necessary, so as to not to kill off the “good bacteria” in your intestines. Regarding specific commercially available probiotics, it is important to note that the European Food Safety Authority has rejected applications by manufacturers of probiotic products for health claims, due to insufficient evidence. Our U.S. Food and Drug Administration has followed suit and takes a similar stance, considering them safe, but not yet proven medically effective.

Foods that are considered probiotic include yogurt, sauerkraut, kimchi, kefir, and certain cheeses, such as cheddar, Gouda, cottage cheese and mozzarella.

Unfiltered apple cider vinegar is not a probiotic, but has been called a “prebiotic,” because the pectin it contains supports the growth of beneficial bacteria, and so accomplishes the same goal..

BOTTOM LINE: This is a promising field! I personally do not take a probiotic, but I am following this field closely. This may also have important implications concerning our diet, since what we eat may turn out to either help or harm the unsung heroes in our gut microbiome. For now, be kind to your intestinal bacteria, and avoid killing them with powerful antibiotics or other antimicrobials unless unavoidable!



    A PATIENT ASKS: “As we get older, many of us find that our blood sugar moves up. What is the impact of “prediabetes level” and actual diabetes levels of A1C on heart health? What do we need to be most careful about?”

    ANSWER: This is an excellent question, and one whose answer is controversial! Official normal for fasting blood glucose (blood sugar) is 70 – 99 at UCSF laboratories. If your fasting blood sugar is 100 – 125 you are considered to have “prediabetes,” and if it is over 125 you have actual or “frank” diabetes. The Diabetes Society, the Joslin Clinic and nearly all endocrinologists prefer a blood test called Hemoglobin A1C, or HbA1c. Specifically, the A1C test measures what percentage of your hemoglobin — a protein in red blood cells that carries oxygen — is coated with sugar (glycated). This reflects the average blood glucose level over two to three months, a much more accurate way to know about your sugar metabolism than a single fasting blood sugar value. Official normal for HbA1c is 4.3 – 5.6%; 5.7 – 6.4% is increased risk for diabetes and 6.5% or higher is diabetes. We now know that many normal people over age 60 have fasting blood sugar values between 100 and 110. When I find that one of my patients has a blood sugar consistently in this range, I usually order an HbA1c test. Most of the time it will be low, less than 6.0%. I do not get worried unless there is a family history of diabetes, and the HbA1c is close to the magic 6.5% number. True diabetes is usually associated with A1C levels well over 7, and many diabetes specialists will not prescribe diabetic medication for patients with HbA1c between 6.5 and 7, because the risk of the medication can outweigh the gain. If your blood sugar AND your HbA1c are both elevated, what can you do? For most of us, the answer is simple: lose weight! Most Type 2 (adult-onset) diabetes is associated with obesity, or at least excess weight. Losing that weight will almost always result in a marked lowering of blood sugar and HbA1c.


    BOTTOM LINE: Don’t get too worried if you are over 60 and your fasting blood sugar starts to edge over 100. Ask your doctor to do an HbA1c test, and if that is less than 6, my advice is not to worry!


    A PATIENT ASKS: “How should the new data on benefits of lowering blood pressure to 120 systolic or less (down from 140) be interpreted?”

    ANSWER: This question refers to the SPRINT study (Systolic Blood Pressure Intervention Trial). I gave a preliminary report on this in the December issue of HeartLine, in my RESEARCH IN THE NEWS column. Initial press reports were published in the Wall Street Journal (, Sept 11, 2015).

    The study was sponsored by the National Institutes of Health (NIH) and enrolled more than 9,300 patients with hypertension (high blood pressure) beginning in 2010. Investigators compared usual treatment for hypertension to a goal of 140 mmHg systolic (the top number) blood pressure or less, with intensive treatment of hypertension to a goal of 120 mmHg or less. Half of the patients received an average of about two medications with the goal of lowering their systolic pressure below 140. The other half received an average of three medications with the goal of getting below 120. The group receiving the more aggressive treatment with the goal being 120 mmHg or less showed a reduced risk of heart attack and stroke by almost 30%, and death by almost 25%, compared with the group treated to a target of less than 140 mmHg. The conclusion was that we should be more aggressive in treating hypertension.

    This recommendation represents a major change from the recommendations of the Joint National Commission (JNC) on Hypertension, whose most recent guidelines (JNC 8, published in 2014) are actually quite liberal, as many of you know. The JNC 8 guidelines have raised the target blood pressure level for individuals over 60 years of age, where a target of less than 150 mmHg systolic is now recommended. To suddenly revise this and go to a much more aggressive target of getting the systolic blood pressure to 120 mmHg or less will be a major change. In reading the details of the original study, now that it is published in full, I am concerned about the side effects that resulted from this much more aggressive approach. Emergency Room visits for syncope (passing out), hypotension (very low blood pressure), acute kidney failure, injurious falls, and several other adverse results all were more common with intensive treatment than with usual treatment


    BOTTOM LINE: If I can lower the blood pressure in my patients with hypertension to 120 mmHg systolic or less without causing adverse effects, I will do it. However, this will NOT be easy to accomplish, and will require a slow, incremental approach to treatment. “Slow medicine” is being increasingly recognized as an important way to treat complex patients (, and the treatment of high blood pressure is a good example.



    A PATIENT ASKS: “What is the difference between normal and abnormal heartbeats, what brings on the abnormal heartbeats, and when should we be concerned?”

    ANSWER: Important questions, and ones that I am asked frequently. First, the normal heartbeat is a mechanical contraction of the heart, initiated by an electrical impulse generated within the heart itself. The heart has two upper chambers, the right and left atria, and two lower chambers, the right and left ventricles. The ventricles are much more muscular than the atria, and it is their job to pump blood around the body. When you listen to the heart with a stethoscope, or simply by pressing your ear to someone’s chest, it is the beating of the ventricles that you are hearing. 

    The normal heartbeat is initiated by an electrical impulse generated approximately once per second (60 times per minute) in an area of the right atrium called the sinus node. For this reason, normal heart rhythm is called “normal sinus rhythm.” This impulse spreads through the atria, causing them to contract, and then spreads down to the ventricles, causing them to contract.

    In most of us, there are other areas of the heart (in the atria, the ventricles, or the area between the atria and ventricles, called the atrioventricular node) that are capable of generating an electrical impulse and causing the whole sequence that leads to contraction of the ventricles and a heartbeat. Simply put, if the heartbeat is initiated by the sinus node in the right atrium, it is called a normal heartbeat. If it is initiated from anyplace else, it is often called an “ectopic” or “extra” beat. Almost everyone has at least some ectopic beats, and when we do a Heart Monitor test (either the old Holter Monitor, or the newer 14-day Zio monitor), it is rare not to see at least a few ectopic beats (“a few” might be defined as less than 1% of the total beats). Since everyone has them, it is hard to call them “abnormal.” Certainly for most people they are benign, and pose no danger.

    Ectopic or extra beats are abnormal when they become more frequent, and especially if they lead to an arrhythmia (medical term for a heart rhythm disturbance), such as atrial fibrillation, prolonged supraventricular tachycardia (SVT), or ventricular tachycardia (VT). The definition of each of these arrhythmias is beyond the scope of this column.


    BOTTOM LINE: Suffice it to say, if you are having palpitations and sense that your heart is jumping around, skipping a beat, irregular, or racing without any explanation, see a cardiologist and get an EKG, and if needed, a Heart Monitor test.

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