Quotes

The Pearson Potato Theory of Obesity

The skeptical cardiologist developed “Pearson’s Potato Hypothesis” aka the potato theory of obesity a few years ago but became bogged down in frying oil and never published it.

Now I’m really glad I never got around to finishing my post on the theory-it appears that defenders of the potato are legion and vocal. ConscienHealth points out that a NY Times piece on the dangers of french fries quoted a Harvard epidemiologist  (Eric Rimm) as calling potatoes “starch bombs” and weapons of “dietary destruction.”

Potatoes rank near the bottom of healthful vegetables and lack the compounds and nutrients found in green leafy vegetables, he said. If you take a potato, remove its skin (where at least some nutrients are found), cut it, deep fry the pieces in oil and top it all off with salt, cheese, chili or gravy, that starch bomb can be turned into a weapon of dietary destruction.

The article goes on to recommend portion size control when dealing with French fries and further quoted Rimm:

“There aren’t a lot of people who are sending back three-quarters of an order of French fries. I think it would be nice if your meal came with a side salad and six French fries.”

Apparently the notion of limiting one’s French fries is abhorrent to many and Rimm has been attacked by thousands in the twitter-sphere.

I happen to think he’s right so I’ll go out on a limb here and post the essence of my theory without all the backing references and statistics with which I had hoped to buttress it.


Pearson Potato Theory of Obesity:

Because potatoes are cheap,  restaurants add lots of them to dishes to make the dishes seem larger and (to some) better and more satiating. Because the potatoes are so gosh darn tasty when sliced up thinly and fried and salted patrons can’t resist eating them even when they are not hungry. Eating any food when you are full is a recipe for….obesity.


To illustrate this issue I’ve started noting what restaurants serve along with the main dish that I’m interested in.

The vast majority of time breakfast orders come with fried potatoes like those below that came with the egg dish that I ordered.potato egg

I was sorely tempted to eat all these fried potatoes although full from my egg dish because when cooked properly the combination of the crispy fat, salt and warm fluffy potato interior is irresistible. Instead I ate just a few and put the rest in a to-go box, took them home, weighed them on a scale and took this picture.

IMG_8758

Interestingly, the weight of the potatoes that I had not consumed was 150 grams which is roughly equivalent to a large order of fries at McDonald’s. A large order of McDonald’s fries gives you 500 calories with 66 grams of carbohydrates,.

Thus, if I had not been disciplined that morning I likely would have ended up consuming more calories in fried potatoes than the main dish and over half of the calories I consume in a typical full day.

French fries (and their (equally addictive to me) cousin the potato chip) are the side for almost all hamburgers and sandwiches served in the US thus the possibility of unintended excess starch bomb consumption extends from breakfast to lunch to dinner in meals consumed outside the home.

Sweet Potatoes Versus Potatoes

In 2015 I pointed out that sweet potatoes which are embraced by nutrition experts are very similar nutritionally to potatoes.

A serving of either one provides 37 grams of carbohydrates and 4 grams of protein. Sweet potatoes have more fiber ( 6 grams vxs 4 grams) but more sugars (12 grams vs 2 grams.)

The Harvard School of Public health has decided potatoes are not a vegetable:

“However, potatoes don’t count as a vegetable on Harvard’s Healthy Eating Plate because they are high in carbohydrate – and in particular, the kind of carbohydrate that the body digests rapidly, causing blood sugar and insulin to surge and then dip (in scientific terms, they have a high glycemic load).”

but gives sweet potatoes a pass.

If sweet potatoes were as ubiquitous as potatoes and became a staple of fast food restaurants and a side for any and all dishes (and if they were separated out from the rest of the vegetable world), I suspect they would also be associated with weight gain.

If, on the other hand, potatoes were not markers of fast, tasty, and easily prepared and consumed food and were only eaten at trendy locavore restaurants or prepared at home, I think they would no longer be associated with obesity.

So, yes it does make sense to ask for a side salad and limit your fries to six (or perhaps seven on days of debauchery) in place of the typical mountain of potato if you are seeking weight loss.

Spudlimitingly Yours,

-ACP

Are Your Palpitations Due to Benign PVCs?

If you feel your heart flip-flopping, then you are experiencing palpitations: a sensation that the heart is racing, fluttering, pounding, skipping beats or beating irregularly.

Often, this common symptom is due to an abnormal heart rhythm or arrhythmia.

The arrhythmias that cause palpitations range from common and benign to rare and lethal, and since most individuals cannot easily sort out whether they have a dangerous or a benign problem, they often end up getting cardiac testing or cardiology consultation.

The most common cause of palpitations, in my experience, is the premature ventricular contraction, or PVC (less commonly known as the ventricular ectopic beat or VEB).

Premature Ventricular Contractions-Electrical Tissue Gone Rogue

The PVC occurs when the ventricles of the heart (the muscular chambers responsible for pumping blood out to the body) are activated prematurely.

This video shows the normal sequence of electrical and subsequent mechanical activation of the chambers of the heart.

To get an efficient contraction, the electrical signal and contraction begins in the upper chambers, the atria, and then proceeds through special electrical fibers to activate the left and right ventricles.

Sometimes this normal sequence is disrupted because a rogue cell in one of the ventricles becomes electrically activated prior to getting orders from above. In this situation, the electrical signal spreads out from the rogue cell and the ventricles contract out of sequence or prematurely.

This results in a Premature Ventricle Contraction.

labeled-pvc
p waves represent depolarization and activation of the atria which are followed normally after120 to 200 milliseconds by the QRS complex which represents activation of the ventricles. The PVC (inside red circle) is wider and weirder and disrupts the regular interval between beats (green lines).

I recorded the above AliveCor tracing in my office on a patient who suffers palpitations due to PVCs (we’ll call her Janet).

The wider, earlier beat (circled in red) in the sequence is the PVC. The prematurity of the PVC means that the heart has not had the appropriate time to fill up properly. As a result, the PVC beat pumps very little blood and may not even be felt in the peripheral pulse. Patients with a lot of PVCs, say ocurring every other beat in what is termed a bigeminal pattern, often record an abnormally slow heart rate because only one-half of the heart’s contractions are being counted.

While recording this, every time Janet felt one of her typical “flip-flops,” we could see that she had a corresponding PVC and the cause of her symptoms was made clear.

There is a pause after the PVC because the normal pacemaker of the heart up in the right  atrium (the sinus node) is reset by electrical impulses triggered by the PVC.. The beat after the PVC is more forceful due to a more prolonged time for the ventricles to fill and  Consequently, most  patients feel this pause after the PVC rather than the PVC itself,

PVCs are common and most often benign. I have patients who have

ECG from 70 year very vigrous man who had 20 thousand PVCs in 24 hours. Every third beat is a PVC (green arrow)
ECG from 70 year old very vigorous man who had 20 thousand PVCs in 24 hours. Every third beat is a PVC (green arrow PVC, blue arrow normal QRS.)This patient feels nothing with his frequent PVCs. He has had them probably lifelong and definitely for the last 10 years without any adverse consequences.

thousands of them in a 24-hour period and feel nothing. On the other hand, some of my patients suffer disabling palpitations from very infrequent PVCs. From an electrical or physiologic standpoint, there seems to be neither rhyme nor reason to why some patients are exquisitely sensitive to premature beats.

How Do I Know If My PVCs Are Benign?

My patient, Janet, is a great example of how PVCs can present and how inappropriate or inaccurate heart tests done to evaluate PVCs can lead to anxiety and unnecessary and dangerous subsequent testing.

A year ago,  Janet began experiencing a sensation of fluttering in her chest that appeared to be random. Her general practitioner noted an irregular pulse and obtained an ECG, which showed PVCS. He ordered two cardiac tests for evaluation of the palpitations: a Holter monitor and a stress echo.

A Holter monitor consists of a device the size of a cell phone connected to two sensors or electrodes that are stuck to the skin of the chest area. The electrical activity of the heart is recorded for 24 or 48 hours, and a technician then scans the entire recording looking for arrhythmias while trying to correlate any symptoms the patient recorded with arrhythmias. The Holter allows us to quantitate the PVCs and calculate the total number of PVCs occurring either singly or strung together as couplets (two  in a row), or triplets (three in a row.)

Janet’s Holter monitor showed that over 24 hours her heart beat  around 100,000 times with around 2500 PVCs during the recording.  Unfortunately, the report did not mention symptoms, so it was not possible to tell from the Holter if the PVCs were the cause of her palpitations.

A stress echocardiogram combines ultrasound imaging of the heart before and after exercise with a standard treadmill ECG. It is a very reasonable test to order in a patient with palpitations and PVCs, as it allows us to assess for any significant problems with the heart muscle, valves or blood supply and to see if any more dangerous rhythms like ventricular tachycardia occur with exercise. If it is normal, we can state with high certainty that the PVCs are benign.

Benign, in this context, means the patient is not at increased risk of stroke, heart attack, or death due to the PVCs.

In the right hands, a stress echocardiogram is superior to a stress nuclear test for these kinds of assessments for three reasons:

-Reduced rate of false positives (test is called abnormal, but the coronary arteries have no significant blockages)

-No radiation involved (which adds to costs and cancer risk)

-The echocardiogram allows assessment of the entire anatomy of the heart, thus detecting any thickening (hypertrophy), enlargement  or weakness of the heart muscle, that would mean the PVCs are potentially dangerous.

Unfortunately, my patient’s stress echo (done at another medical center) was botched and read as showing evidence for a blockage when there was none.  An invasive and potentially life-threatening procedure, a cardiac catheterization was recommended.  Similar to the situation I’ve pointed out with the performance and interpretation of echocardiograms (see here),  there is no guarantee that your stress echo will be performed or interpreted by someone who actually knows what they are doing.  So, although the stress echo in published studies or in the hands of someone who is truly expert in interpretation, has a low yield of false positives, in clinical practice the situation is not always the same.

Given that Janet was very active without any symptoms, she balked at getting the catheterization and came to me for a second opinion. I felt the stress echo was a false positive and did not feel the catheterization was warranted. We discussed alternatives, and because Janet needed more reassurance of the normality of her heart (partially because her father had died suddenly in his sixties) and thus the benignity of her palpitations/PVCs, she underwent a coronary CT angiogram instead. This noninvasive exam (which involves IV contrast administration, and is different from a coronary calcium scan), showed that her coronary arteries were totally normal.

lad-ccta
Images from Janet’s coronary CT angiogram showing the left anterior descending (LAD) coronary artery coming off the aorta. The LAD (and her other coronaries) were totally free of any plaque build-up.)

Benign PVCs-Treatment Options

Once we have demonstrated that the heart is structurally normal, reassurance is often the only treatment that is needed.  Now that the patient understands exactly what is going on with the heart and that it is common and not dangerous, they are less likely to become anxious when the PVCs come on.

PVCS can create a vicious cycle because the anxiety they provoke can cause  an increase in neurohormonal factors (catecholamines/adrenalin) that may increase heart rate , make the heart beat stronger and increase the  frequency of the PVCs.

Some patients, find their PVCs are triggered by caffeine (tea, soda, coffee, chocolate) or stress, and reducing or eliminating those triggers helps greatly. Others, like Janet, have already eliminated caffeine, and are not under significant stress.

Since I’m already over a thousand words in this post, I’ll discuss treatment options for these patients with benign PVCs who continue to have troubling symptoms after reassurance and caffeine reduction in a subsequent post.

Prematurely Yours,

-ACP