Heart attack guaranteed

What if you knew for a fact that your risk for heart attack was 100% by, say, age 58? This is indeed true for many people, though at age 60, 65, 70--or 45.

In other words, unless something were done about the causes of heart disease, you would inevitably suffer a heart attack at 58.

What sort of action could you take at age 45?

Obviously, not smoking is an absolute requirement. Continue and you may as well start getting your affairs together.

How about exercising and eating a generally healthy diet? Will your risk be reduced to zero? No. It might be reduced 20-30%, depending on genetic factors.

How about a statin drug? Watch TV ads during Oprah, and you might think it's a cure. But in reality, while it is a financial bonanza for the drug manufacturers, it will reduce risk for heart attack by 30%.

(Note that risk reduction by following multiple strategies is not necessarily additive. In other words, if you have a healthy lifestyle and take a statin agent, is risk reduced 60% (30 + 30)? No, because the effects may overlap.)

So, eating healthy, exercising, and taking a statin drug might reduce risk 35-40%, maybe 50% in the best case scenario. Would you be satisfied? Most would not.

Add fish oil at a truly therapeutic dose. Risk reduction by itself: 28%.

Add niacin or other strategies for correction of your individual, specific causes of heart disease: Now we're up to 90% reduction.

Throw in a tracking process to prove whether or not atherosclerotic plaque has progressed or reversed. Now we're approaching 100% if plaque reverses. The only way I know how to track plaque is through CT heart scans. What other test is readily available to you with low radiation exposure, yet is relatively inexpensive and precise? It certainly is not stress testing, heart catheterization, CT angiograms, or other techniques. Cholesterol won't tell you. Besides CT heart scans, there's nothing else I know of.

Let's fact it: For many people, uncorrected risk for heart attack is truly 100% at some age. Take action while you can.

That, in a nutshell, is the Track Your Plaque program.

Heart scan curiosities 3



This is a sample image from the heart scan of a 54-year old, 212 lb, 5 ft 2 inch woman. The heart is the whitish-gray in the center; lungs are the dark (air-filled) areas on either side of the heart. Note the massive amount of surrounding gray tissues that encircles the heart and lungs. This is fat. At this weight, the diameter of total fat exceeds the combined diameter of the heart and lungs. If we were to show the abdomen, there would be even more fat. (The image shows the body not well centered because the technologist centers the heart, since this is, after all, a heart scan.)





This is a 55-year old, 151 lb, 5 ft 4 inch woman. Note the contrast in the quantity of fat tissue surrounding the chest, a much more normal appearance. Note that this woman is still around 25 lb over ideal weight, but not to the extreme degree of the woman above.

Another curious observation: Note the more whitish streaking in the heavier woman's lungs. Heart scans are performed while holding a deep inspiration (a deep breath inwards), mostly to eliminate lung respiratory motion during image acquisition. Nonetheless, the heavier woman's lungs are not as fully expanded as the more slender woman. In other words, the heavier woman cannot inflate her lungs as effectively as the thinner woman. Ever notice how breathless heavy people are? Some of this effect is just being out of shape. But there's also the added effect of the abdominal fat exerting upwards compression on the lung tissues, and the constrictive effect of the encircling fat mass. At the beginning of inspiration, the chest fat exerts the resistance of inertia to inspiration that is absent, or less, in a slender person. With each breath, the heavy woman must move 50 lbs or so of surrounding fat mass just to inhale.

The heavier woman is, in effect, suffocating herself in fat.

The distortions to the human body incurred by extreme weight gain are both fascinating and shocking. I hope you're breathing easily.

The shameful "standard of care"

John's initial heart scan four years ago showed a score of 329. His physician prescribed Zocor for a somewhat high LDL cholesterol.

One year later, John asked for another scan. His score: 385, a 17% increase. John exercised harder and cut his fat intake.

This past fall--3 years after his last scan--John had yet another heart scan. Score: 641, a 66% increase over the last scan, all the while on Zocor.

John sought an opinion from a reputable cardiologist. He concurred with the prescription of Zocor and advised annual stress tests. That's it.

Followers of the Track Your Plaque approach know that the expected uncorrected rate of increase in heart scan score is 30% per year. On Zocor or other cholesterol reducing statin agent, a common rate of growth is between 18-24% per year--better but not great. Plaque growth is certainly not stopped.

But that is the full extent of interest and responsibility of your cardiologist. Prescribe a statin drug, perform a stress test, and the full extent of his obligation has been fulfilled. In legal terms, your physician has met the prevailing
"standard of care". No more, no less.

In other words, the prevailing standard of care falls shamefully short of what is truly possible. For the majority of the motivated and interested, coronary plaque reversal--reduction of your heart scan score--should be the standard aimed for. It's not always achievable, but it is so vastly superior to the prescribe statin, wait for heart attack approach endorsed by most cardiologists.

Heart scan curiosities 2



This is an example of a so-called "hiatal hernia", meaning the stomach has migrated through the diaphragmatic hiatus into the chest--the stomach is literally in the chest. This example is an unusually large one. Hiatal hernias can cause chest pain, indigestion, and a variety of other gastrointestinal complaints. Heart scans are reasonably useful to screen for this disorder, though very small ones could escape detection by this method.

Sometimes, you can actually hear the gurgling of stomach contents (the common "growling" stomach) by listening to the chest. Large ones like this actually crowd your heart (the gray structure above the circled hernia), irritating it and even causing abnormal rhythm disorders. The dense dark material within the hernia represents lunch.

I would not advocate CT heart scans as a principal method to make a diagnosis, but sometimes it just pops up during a heart scan and we pass it on to the person scanned.

Vitamin D: New Miracle Drug

At the meetings of the American Society of Bone and Mineral Research, Dr. Bruce Troen of the University of Miami detailed his views on the extraordinary benefits of vitamin D replacement. He also talked about the enormous problem of unrecognized vitamin deficiency.

“There’s a huge epidemic of hypovitaminosis D, and the real key here is not just that it’ll benefit you from a bone and neuromuscular standpoint, but if you correct hypovitaminosis D and the corresponding secondary hyperparathyroidism, then you’re going to decrease prostate cancer, colon cancer—actually “up to 17 different cancers, breast cancer included.”

Unfortunately, Dr. Troen did not talk much about the heart benefits of vitamin D, likely since the data is scant, nearly non-existent. However, if the Track Your Plaque experience means anything, I predict that vitamin D replacement will become among the most powerful tools you can use to gain control over coronary plaque.

Read the text of a report from the Internal Medicine World Report to read more of Dr. Troen's comments.


http://www.imwr.com/article.php?s=IMWR/2006/11&p=40

Heart disease "reversal" by stress test


Here's an interesting example of a 71-year old man who achieved "reversal" of an abnormality by a nuclear stress test.

This man underwent bypass surgery around 10 years ago, two stents three years ago. A nuclear stress test in April, 2005 showed an area of poor blood flow in the front of the heart. On the images, normal blood flow is shown by the yellow/orange areas. poor or absent blood flow is shown by the blue/purple areas within the white outline.

Now, I can tell you that this man is no paragon of health. He's only accepted limited changes in his otherwise conventional program--in other words, someone who I'd be shocked achieved true reversal of his heart disease. (I didn't have him undergo any CT heart scans because of the difficulties in scoring someone who has undergone bypass surgery and stents, and because of limited motivation. True plaque reversal is for the motivated.)This patient did, however, accept adding fish oil and niacin to his program.

Nonetheless, stress testing can be helpful as a "safety check". Here's the follow-up stress test:
You'll notice that the blue/purple areas of poor blood flow have just about disappeared. This occurred without procedures.

Does this represent "reversal"? No, it does not. It does represent reversal of this phenomenon of poor flow. It does not represent reversal of the plaque lining the artery wall. That's because improvement of flow, as in this man, can be achieved with relatively easy efforts, e.g., improvement in diet, statin drugs, blood pressure control, etc. True reversal or reduction of coronary plaque, however, is tougher.

If blood flow is improved, who cares whether plaque shrinks? Does it still matter? It does. That's because the "event" that gets us in trouble is not progressive reduction in blood flow, but "rupture" of a plaque. A reduction in plaque--genuine reversal--is what slashes risk of plaque rupture.

Calcium reflects total plaque





People frequently ask, "Why measure coronary artery calcium? My doctor said that calcium only tells you if there's hard plaque, and that hard plaque is stable. He/she says that calcium doesn't tell you anything about soft plaque."

Is that true? Is calcium only a reflection of "hard" plaque? Is hard plaque also more stable, less prone to rupture and causes heart attack?

Actually, calcium is a means of measuring total plaque, both soft and hard. That's because calcium comprises 20% of total plaque volume. Within plaque, there may be areas that are soft (labeled "lipid pool" in the diagram). There are also areas made of calcium (shown in white arcs within the plaque). Even though this is just a graphic, it's representative of what is seen when we perform intracoronary ultrasound of a live human being's coronary artery. In other words, this cross section contains both "soft" (lipid pool) as well as "hard" (calcium) elements.

Is this artery "soft" or "hard"? It's both, of course. The artery compostion can vary millimeter by millimeter, having more soft or hard elements. The artery can also change over time in either direction. Thus, "soft" plaque may indeed be soft today, only to be "hard" in 6 months, and vice versa.

The essential point is that measuring just "soft" plaque provides limited information. What the CT heart scan does is provide a gauge of total plaque, soft and hard, and it does so easily, safely, precisely. If your score increases, the lengthwise volume of total plaque has also grown. If your score decreases, the total amount of plaque has also decreased.

Don't mistake marketing for truth

We're all so inundated with marketing messages for food. Unfortunately, many people confuse the messages delivered through marketing with the truth.

For instance:

Pork: "The other white meat." Pork is a high-saturated fat food.

"Bananas: A great source of potassium." Bananas are a high glycemic index (rapid sugar release), low fiber food.

"Pretzels: A low-fat snack." A high glycemic index food made from white wheat flour. It makes you fat and skyrockets blood sugar.

Jif peanut butter: "Choosy moms choose Jif." Do they also choose hydrogenated fats?

Hi-C: Upbeat jingles like "Who put the straw in my Hi-C fruit drink, a new cool straw that wriggles and bends? Who put the straw in my Hi-C fruit drink, with Vitamin C for me and my friends? Who was that man, I'd like to shake his hand, he made my Hi-C cooler than before!" What about the 25 grams of sugar per 4 oz serving? And the high fructose corn syrup that creates an insatiable sweet tooth, raises triglycrides 30%, and exagerates pre-diabetes?


Marketing is not reliable, unbiased information. If Ford boasts that their cars are superior to GM, do you say "Well then, I need to buy a Ford?" Of course not. Take marketing for what it is: A method of persuading people to buy. It may or may not contain the truth. It's a big part of the reason Americans are the fattest people on earth and are experiencing an explosion of chronic diseases of excess.

Tattered Red Dress

"Are you taking your health to heart? Perhaps you understand the importance of eating a diet low in cholesterol or getting 30 minutes of exercise a day. But do you know your own risk of developing cardiovascular disease?


It’s time to take your heart health personally. Heart disease is the No. 1 killer of American women — and that means it is not “someone else’s problem.” As a woman, it’s your problem.

That’s where the Go Red Heart Checkup comes in. This comprehensive evaluation of your overall heart health can help you now and in the future. By knowing your numbers and assessing your risks now, you can work with your doctor to significantly reduce your chances of getting heart disease tomorrow, next year, or 30 years from now!"



So reads some of the materials promoted by the American Heart Association Red Dress campaign to increase awareness of heart disease in women. The effort is well-intended. There is no doubt that most women are unaware of just how common coronary disease is in females.

But I've got a problem with the solutions offered. "Know your numbers"? Eat healthy, don't be overweight, be active, don't smoke. That's the gist of the program's message--nothing new. In 2006, why would some sort of screening effort for detectin of heart disease not be part of the message? Why isn't there any message about the real, truly effective means to detect hidden heart disease in women--namely, heart scanning?

Does a 58-year old woman with normal blood pressure, LDL 144, HDL 51, 20 lbs overweight have hidden heart disease? I've said it before and I'll say it again: You can't tell from the numbers. She could die of a heart attack tomorrow without warning, or maybe she'll be dancing on our graves when she's 95 and never have experienced any manifestation of heart disease. The numbers will not tell you this.

I'm glad the American Heart Association has seen fit to invest its sponsors' money in a campaign to promote prevention. I wish they hadn't fallen so far short of a truly helpful message. Perhaps the sponsors (like Pfizer, maker of Lipitor) will benefit, anyway.

Panic in the streets

Several days ago, I wrote about a local prominent judge in my neighborhood who was unexpectedly found dead in bed of a heart attack at age 49.

As expected, I've received multiple calls from patients and physicians who want heart catheterizations. For instance, an internist I know called me in a panic. He asked that I perform a heart catheterization in a patient with a heart scan score of 768. I've been seeing this patient for about a year. He's without symptoms, even with strenuous exercise; stress tests (i.e., tests of coronary bloow flow) have been normal.

I remind patients and colleagues every day, day in day out: Having a heart scan score revealing some measure of coronary plaque is not a sufficient reason by itself to proceed with procedures. Fear of suffering a fate like the unfortunate judge is also not a reason to proceed with procedures.

Increased awareness of the gravity of heart disease is a good thing. Some good can come out of a needless tragedy like this. The lesson from the judge's unfortunate experience: he needed a CT heart scan. I'm told that the judge's doctor advised him that a heart scan was a waste of time. I hope that appropriate legal action for negligence is taken by the judge's family against this physician.

Not doing a heart scan is wrong. That's the lesson to learn. The lesson is not that everybody with coronary plaque needs a procedure. Had the judge undergone a simple heart scan, intensified prevention could have been instituted and he'd still be alive with his wife and children today.

The indications for procedures are unchanged by your heart scan. If a stress test is abnormal and indicates poor flow to a part of the heart, that would be a reason. If symptoms like chest discomfort or breathlessness appear, that's an indication. If there's evidence of poor heart muscle contraction, that's a reason to proceed with a procedure. But just having coronary plaque is not a sufficient reason.
All posts by william-davis

Statin stupid

If we followed the lead of the pharmaceutical industry and my cardiology colleagues, we would all subscribe to the "statins for all" philosophy. There is now $2 billion of clinical "research" to back up this "evidence-based" practice.

I do not endorse this "statins for all" philosophy. I believe it is a product of the raw profiteering of the pharmaceutical industry, who are adept at recruiting physicians to their cause.

But lost in the confusion of tainted studies and over-the-top media saturation is the fact that there are small groups of people who likely do obtain benefit from statin drugs. They would certainly benefit from better informed scrutiny of their lipoprotein and metabolic abnormalities. But treatment may involve statins.

This is entirely distinct from the "statins for all" argument, the simpleminded rule that primary care physicians and cardiologist are told to follow.

Groups who may indeed benefit from statin therapy include:

Homozygous or heterozygous familial hypercholesterolemia--Lacking a receptor for LDL particles, LDL piles up to very high levels in these people. LDLs of 300+ are common and lead to heart disease and stroke at relatively young ages.

Combined mixed hyperlipidemia--Among the one or more genetic defects underlying this condition involves excessive production of apoprotein B and VLDL particles. This leads to high risk for heart disease.

People unable to follow a diet to correct their lipid disorder--I have 80+-year old patients, for instance, who say, "I've eaten this way for 82 years. I'm not going to change now!" In the absence of diet and other efforts (e.g., omega-3 fatty acids from fish oil), drugs may be the answer.

In other words, of the $27 billion annual bill for statin drugs, perhaps a tiny fraction is truly necessary. The majority of people taking statin drugs would not really need them if they had the real answers. But don't let that confuse us: There are some people who do indeed benefit.

Butter and insulin

In a previous post, Atkins Diet: Common Errors, I commented on butter's unusual ability to provoke insulin responses. I offer this as a possible reason why, after a period of effective weight loss on a low-carbohydrate program, inclusion of some foods, such as butter, will trigger weight gain or stall weight loss efforts.

This develops because of butter's insulin-triggering effect, doubling or tripling insulin responses (postprandial area-under-the-curve). If insulin is triggered, fat gain follows.

Here's one such study documenting this effect: Distinctive postprandial modulation of ß cell function and insulin sensitivity by dietary fats: monounsaturated compared with saturated fatty acids

López et al 2008


From Lopez et al 2008. Mean (± SD) plasma glucose, insulin, triglyceride, and free fatty acid (FFA) concentrations during glucose and triglyceride tolerance test meal (GTTTM) with no fat (control), enriched in monounsaturated fatty acids (MUFAs) from refined olive oil (ROO meal), with added butter, with a mixture of vegetable and fish oils (VEFO) or with high-palmitic sunflower oil (HPSO). N = 14.

The postprandial (after-eating) area-under-the-curve is substantially greater when butter is included in the mixed composition meal. This effect is not unique to butter, but is shared by most other dairy products.

Fat, in general, does not make you fat. But butter makes you fat.

Vitamin D as a cardiovascular risk factor gains ground

If you were reading The Heart Scan Blog back in 2007, or read my Life Extension article on vitamin D deficiency as a cardiovascular risk factor, you already knew that vitamin D deficiency is rampant and adds to cardiovascular risk.

Results of a study from the Intermountain Medical Center Heart Institute in Utah bolster the concept that vitamin D deficiency is a cardiovascular risk factor, vitamin D normalization/supplementation reduces cardiovascular risk.

Science Daily reported:

For the first study, researchers followed two groups of patients for an average of one year each. In the first study group, over 9,400 patients, mostly female, reported low initial vitamin D levels, and had at least one follow up exam during that time period. Researchers found that 47 percent of the patients who increased their levels of vitamin D between the two visits showed a reduced risk for cardiovascular disease.


In the second study, researchers placed over 31,000 patients into three categories based on their levels of vitamin D. The patients in each category who increased their vitamin D levels to 43 nanograms per milliliter of blood or higher had lower rates of death, diabetes, cardiovascular disease, myocardial infarction, heart failure, high blood pressure, depression, and kidney failure. Currently, a level of 30 nanograms per milliliter is considered "normal."


Over the past 4 years, people in our program have been enjoying the extravagant benefits of vitamin D restoration. Cardiovascular benefits are becoming better documented and the bone health, cancer-preventing, insulin-normalizing, mood-adjusting, and anti-inflammatory effects likewise.

Atkins Diet: Common errors

No doubt: The diet approach advocated by the late Dr. Robert Atkins was a heck of a lot closer to an ideal diet than the knuckleheaded advice emitting from the USDA, American Heart Association, American Diabetes Association, and the Surgeon General's office.

But having just spent a week with Atkins low-carbers, here are some common errors that I see many make, errors that I believe have long-term health consequences, including impairment of weight loss.

Excessive consumption of animal products--Non-restriction of fat often leads to over-reliance on animal products. Higher intakes of red meats (heme proteins?) have been strongly associated with increased risk for colon and other gastrointestinal tract cancers. It is not a fat issue; it is an animal product issue. We should consume less meat, more vegetables and other plant-sourced foods.

Consumption of cured meats--Cured, processed meats, such as sausage, hot dogs, salami, bologna, and bacon, have a color fixative called sodium nitrite, an additive that has been confidently linked to gastrointestinal cancers. Risk is likely dose-dependent: The more you ingest, the greater the long-term risk.

Overconsumption of dairy products--Dairy products, especially milk, yogurt, cottage cheese, and butter, are potent insulinotropic foods, i.e., foods that trigger insulin release. There can be up to a tripling of insulin (area-under-the-curve) levels. This is not good in a world populated with tired, overworked pancreases, exhausted from a lifetime of high-carbohydrate eating.

Too many calories--While I agree that "a calorie is a calorie" and "calories in, calories out" are faulty concepts, I have anecdotally observed that long-time low-carbers often trend towards unlimited consumption of food, a phenomenon that seems to result in weight gain, especially in the sedentary. I wonder if this is a reflection of the insulinotropic action of dairy products and other proteins, compounded by the poor insulin responsiveness that develops with lack of physical activity. Factor into this conversation that lower calorie intake extends life, probably substantially (Sirt-2 activation and related phenomena, a la resveratrol). If lower calorie intake extends life, unlimited calorie intake likely shortens life.

Please don't hear this as low-carb bashing--it is not. It is a call to improve diets and not stumble into common traps that can impair heart health, weight loss, and longevity.

Fat Head: Tom Naughton's manifesto for low-carb eating

I just got back from Jimmy Moore's low-carb cruise to the Bahamas.

Among the many interesting people I met on the cruise was the creator of the documentary film, Fat Head, Tom Naughton.

Tom brings both creative insights into low-carbohydrate eating as well as humor. Low-carb eating can be a pretty contentious issue, but Tom made it fun. He will make you laugh about many of the odd notions we have about diet.

Among the best parts of Fat Head is Tom's portrayal of the effects of carbohydrates on insulin and fat metabolism:






Fat Head joins the ranks of films like Food, Inc, that make nutrition information entertaining. For anyone interested in a unvarnished look at diet, weight loss, along with a few laughs along the way, Tom Naughton's Fat Head is worth viewing.

Oatmeal: Good or bad?


You've heard it before: oatmeal reduces cholesterol. Oatmeal producers have obtained permission from the FDA to use a cholesterol-reducing claim. The American Heart Association provides a (paid) endorsement of Quaker Oats.

I've lost count of the times I've asked someone whether they ate a healthy breakfast and the answer was "Sure. I had oatmeal."

Is this true? Is oatmeal heart healthy because it reduces LDL cholesterol?

I don't think so. Try this: Have a serving of slow-cooked (e.g., steel-cut, Irish, etc.) oatmeal. Most people will consume oatmeal with skim or 1% milk and some dried or fresh fruit. Wait an hour, then check your blood sugar.

If you are not diabetic and have a fasting blood sugar in the "normal" range (<100 mg/dl), you will typically have a 1-hour blood glucose of 150-180 mg/dl--very high. If you have mildly increased fasting blood sugars between 100 and 126 mg/dl, postprandial (after-eating) blood sugars will easily exceed 180 mg/dl. If you have diabetes, hold onto your hat because, even if you take medications, blood sugar one hour after oatmeal will usually be between 200 and 300 mg/dl.

This is because oatmeal is converted rapidly to sugar, and a lot of it. Even if you were to repeat the experiment with no dried or fresh fruit, you will still witness high blood sugars in these ranges. Do like some people and pile on the raisins, dried cranberries, or brown sugar, and you will see blood sugars go even higher.

Blood sugars this high, experienced repetitively, will damage the delicate insulin-producing beta cells of your pancreas (glucose toxicity). It also glycates proteins of the eyes and vascular walls. The blood glucose effects of oatmeal really don't differ much from a large Snickers bar or bowl of jelly beans.

If you are like most people, you too will show high blood sugars after oatmeal. It's easy to find out . . . check your postprandial blood sugar.

In past, I recommended oat products, specifically oat bran, to reduce LDL, especially small LDL. I've changed my mind: I now no longer recommend any oat product due to its blood sugar-increasing effects.

Better choices: eggs, ground flaxseed as a hot cereal, cheese (the one dairy product that does not excessively trigger insulin), raw nuts, salads, leftovers from last evening's dinner.

Mustard: Super health food?

Could mustard--yes, the yellow condiment you smear on hot dogs--be a super heart healthy food in disguise?

Consider that mustard contains:

Vinegar

Turmeric

No appreciable sugar


The vinegar slows gastric emptying, resulting in slower absorption of any carbohydrates and a reduced glucose area-under-the-curve. Of the little fats contained (about 3 grams per 1/4 cup), most are desirable monounsaturates. Mustards are relatively rich in selenium, with 20 mcg per 1/4 cup, helpful for protection against cancer and thyroid disease, and magnesium, 31 mg per 1/4 cup.

Turmeric is added to most mustards. One of the constituents of turmeric, curcumin, the substance that confers the bright yellow color, has been a focus of interest for its anti-inflammatory effects. Curcumin has been documented to reduce activity of the inflammatory enzymes cyclooxygenase-2 (COX-2), lipoxygenase, and reduce activity of inflammatory signal molecules, tumor necrosis factor-alpha (TNF-a), interleukin (IL)-1,2,6,8, and 12, and monocyte chemoattractant protein (MCP). Curcumin also has been shown to reduce LDL oxidation, a potentially important step in atherosclerotic plaque formation. Turmeric is used as a tea by Okinawans. (Hmmmm . . . )

Turmeric content of mustard can vary, of course. Likewise, sugar content. Look for mustards that are not sweetened, so avoid honey mustard in particular. Look for hot, brown, horseradish, Dijon, etc. If there is a downside to mustard, it's sodium content, though the 709 mg per 1/4 cup should only be a problem for those who are sodium-sensitive (African Americans, in particular).

So perhaps mustard isn't exactly a super health food. But it may have some bona fide health effects and should be used generously especially if you are concerned about blood sugar and inflammatory phenomena.

Exercise and blood sugar

There is no doubt that exercise yields benefits across a spectrum of health: reduced blood pressure,  reduced inflammation, reduced blood coagulation, better weight control, stronger bones, less depression, reduced risk for heart attack.

Exercise also influences blood sugar. Diabetics understand this best: Exercise reduces blood sugar 20, 30, 50 or more milligrams. A starting blood sugar, for instance, of 160 mg/dl can be reduced to 80 mg/dl by jogging or riding a bicycle. (I recently had brunch at an Indian restaurant with my family. Blood sugar one-hour postprandial: 134 mg/dl. I was sleepy and foggy. I got on my stationary bike and pedalled at a moderate clip for 60 minutes. Blood sugar: 90 mg/dl.)

Could the reduction of blood sugar with exercise be THE reason that exercise and physical activity provide such substantial benefits?

Think about it. Reduced blood sugar:

1) Reduces risk for future cardiovascular events.
2) Reduces glycation of proteins, i.e., reduced glucose binding to proteins like the ones in artery walls and the lenses of your eyes.
3) Reduces blood coagulation
4) Reduces endothelial dysfunction (abnormal artery constriction that leads to atherosclerosis)

This might explain why it doesn't require high levels of aerobic activity to derive benefit from exercise, since even modest efforts (e.g., a 15-minute walk after eating) reduce blood sugar substantially.

The incredible 33-year, 18,000-participant Whitehall study tells us that a postprandial (after-eating) blood sugar of an impossibly-difficult 83 mg/dl is required to erase the excess cardiovascular risk of blood sugar. Could this simply be telling us that physical activity or exercise is required to suppress blood sugars to these low levels?

It makes me wonder if an index of the adequacy of exercise is your post-exercise blood glucose.