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.

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.

Timing of blood sugars

Because different foods generate different blood sugar (glucose) responses, the timing of your blood sugar is an important factor to consider.



This question has come up a number of times. Commenters have asked whether the one-hour postprandial glucose is timed with the start of the meal or the conclusion of the meal.



In my view, if we simply ignored all aspects of meal composition, then blood glucose should be obtained one hour after the conclusion of a meal. This is because most mixed meals (i.e., mixed in composition among proteins, fats, and carbohydrates) yield peak blood glucose levels at 60-90 minutes after consumption. Timing blood glucose to 60 minutes after the conclusion of a meal puts the sample right about at the peak.



But this is an oversimplification. For instance, here is the blood glucose behavior after so-called "complex" carbohydrates wheat bread, rye bread, rye made with beta glucan, and whole wheat pasta (50 grams carbohydrates each) in slender, healthy volunteers, mean age 29 years:

From Juntunen et al 2002



Note that blood glucose peaks at 35 minutes postprandial. (To convert glucose in mmol/L to mg/dl, multiple by 18. Thus, whole wheat bread increased blood glucose from 94 mg/dl to 122 mg/dl. Also note the lower peak glucose for pasta, but sustained higher glucose levels hours later.)



In another study, older (mean age 64 years), overweight (BMI 27.9) females with diabetes were given 50 grams carbohydrate, 50 grams carbohydrate with olive oil, or 50 grams carbohydrate with butter:

From Thomsen et al 2003. Control meal of soup plus 50 g carbohydrates (), the control meal plus 80 g olive oil (), and the control meal plus 100 g butter (•).



In this experience, note that postprandial glucose peaks 60-120 minutes after the meals (consumed within 10 minutes), delayed more when either oil is included. Blood glucose started at 144 mg/dl and peaked as high as 230 mg/dl with carbohydrates only; peaks were reduced (along with AUC) when oil was included. (Note the differential effect, olive oil vs. butter.)



These two sets of observations give you a range of blood glucose behavior. One side lesson: Carbohydrates should never consumed by themselves, else you will pay with a high blood sugar (not to mention the hypoglycemic response later for many).

Psssst . . . There's sugar in there

You non-diabetics who check your postprandial blood sugars already know: There are hidden sources of sugar in so many foods.

By now, everybody should know that foods like breakfast cereals, breads, bagels, pretzels, and crackers cause blood sugar to skyrocket after you eat them. But sometimes you eat something you thought was safe only to find you're showing blood sugars of 120, 130, 150+ mg/dl.

Where can you find such "stealth" sources of sugars that can screw up your postprandial blood sugars, small LDL, inflammation, blood pressure, and cause you to grow visceral fat? Here's a few:

Balsamic vinaigrette
Many commercially-prepared balsamic vinaigrettes, especially the "light" varieties, have 3 or more grams carbohydrates per tablespoon. Generous use of a sugar-added vinaigrette can therefore provide 12+ grams carbs. (Some, like Emeril's and Wish Bone, also contain high-fructose corn syrup.)

Hamburgers
I learned this lesson the hard way by taking my blood sugar after having a hamburger, turkey burger, or vegetarian burger (without bun): blood sugar would go way up. The effect is due to bread crumbs added to the meat or soy.

Tomato soup
If it were just tomatoes, it would still be somewhat high in sugars. But commercially-prepared tomato soup often contains added high-fructose corn syrup, sucrose, and wheat flour, bringing sugar totals to 12 to 20+ grams per half-cup. A typical 2-cup bowl of tomato soup can have upwards of 80 grams of sugar.

Granola
Sure, granola contains a lot of fiber. But most granolas come packed with sugars in various forms. One cup of Kellogg's Low-fat Granola with Raisins contains an incredible 72 grams (net) carbohydrates, of which 25 grams are sugar.


Given modern appetites and serving sizes, you can see that it is very easy to get carried away and, before you know it, get exposed to extraordinary amounts of sugar and carbohydrates eating foods you thought were healthy.

And don't be fooled by claims of "natural" sugar. Sugar is sugar--Just check your blood sugar and you'll see. So raw cane sugar, beet sugar, and brown sugar have the same impact as white table sugar. Honey, maple syrup, and agave? They're worse (due to fructose).

You just THINK you're low-carb

Systematically checking postprandial (after-eating) blood sugars is providing some great insights into crafting a better diet for many people.

I last discussed the concept of postprandial glucose checks in To get low-carb right, you need to check blood sugars.

Here are some important lessons that many people--NON-diabetic people, most with normal blood glucoses or just mildly increased--are learning:

Oatmeal yields high blood sugars. Even if your fasting blood sugar is 90 mg/dl, a bowl of oatmeal with skim milk, walnuts, and some berries will yield blood sugars of 150-200 mg/dl in many people.

Cheerios yields shocking blood sugars. 200+ mg/dl is not uncommon in non-diabetics. (Diabetics have 250-350 mg/dl.)

Fruits like apples and bananas increase blood sugar to 130 mg/dl or higher.

Odd symptoms, such as mental "fog," fatigue, and a fullness in the head, are often attributable to high blood sugars.

A subset of people with lipoprotein(a) can have wildly increased blood sugars despite their slender build and high aerobic exercise habits.


Once you identify the high blood sugar problem, you can do something about it. The best place to start is to reduce or eliminate the sugar-provoking food.

Gastric emptying: When slower is better

When it comes to the Internet and Nascar, speed is good: The faster the better.

But when it comes to gastric emptying (the rate at which food passes from the stomach and into the duodenum and small intestine), slower can be better.

Slower transit time for foods passing through the stomach leads to lower blood sugar, lower blood glucose area under-the-curve (AUC), i.e., reduced blood glucose levels over time. Lower postprandial (after-eating) blood sugars can reduce cardiovascular risk. It can lead to a reduction in net calorie intake and weight loss.

Strategies that can slow gastric emptying include:

--Minimizing fluids during a meal--Drinking a lot of fluids, e.g., water, accelerates gastric emptying by approximately 20%.

--Cinnamon--While the full reason to explain Cassia cinnamon's blood glucose-reducing effect has not been completely worked out, part of the effect is likely to due slowed gastric emptying. Thus, a 1/4-2 teaspoons of cinnamon per day can reduce postprandial blood sugar peaks by 10-25 mg/dl.

--Vinegar--Two teaspoons of vinegar in its various forms slows gastric emptying. The effect is likely due to acetic acid, the compound shared by apple cider vinegar, white vinegar, red wine vinegar, Balsamic vinegar, and other varieties.

--Increased fat content--Fat is digested more slowly and slows gastric emptying time, compared to the rapid transit of carbohydrates.

Not everybody should slow gastric emptying. Diabetics with a condition called diabetic gastroparesis should not use these methods, as they can further slow the abnormal gastric emptying that develops as part of their disease, making a bad situation worse.

However, in the rest of us with normal gastric emptying time, a delay in gastric emptying can reduce blood sugar and induce satiety, effects that can work in your favor in reducing cardiovascular risk.

Carbohydrate sins of the past

Fifty years ago, diabetes was a relatively uncommon disease. Today, the latest estimates are that 50% of Americans are now diabetic or pre-diabetic.

There are some obvious explanations: excess weight, inactivity, the proliferation of fructose in our diets. It is also my firm belief that the diets advocated by official agencies, like the USDA, the American Heart Association, the American Dietetic Association, and the American Diabetes Association, have also contributed with their advice to eat more “healthy whole grains.”

When I was a kid, I ate Lucky Charms® or Cocoa Puffs® for breakfast, carried Hoho’s® and Scooter Pies® in my lunchbox, along with a peanut butter sandwich on white bread. We ate TV dinners, biscuits, instant mashed potatoes for dinner. Back then, it was a matter of novelty, convenience, and, yes, taste.

What did we do to our pancreases eating such insulin-stimulating foods through childhood, teenage years, and into early adulthood? Did our eating habits as children and young adults create diabetes many years later? Could sugary breakfast cereals, snacks, and candy in virtually unlimited quantities have impaired our pancreas’ ability to produce insulin, leading to pre-diabetes and diabetes many years later?

A phenomenon called glucose toxicity underlies the development of diabetes and pre-diabetes. Glucose toxicity refers to the damaging effect that high blood sugars (glucose) have on the delicate beta cells of the pancreas, the cells that produce insulin. This damage isirreversible: once it occurs, it cannot be undone, and the beta cells stop producing insulin and die. The destructive effect of high glucose levels on pancreatic beta cells likely occurs through oxidative damage, with injury from toxic oxidative compounds like superoxide anion and peroxide. The pancreas is uniquely ill-equipped to resist oxidative injury, lacking little more than rudimentary anti-oxidative protection mechanisms.

Glucose toxicity that occurs over many years eventually leaves you with a pancreas that retains only 50% or less of its original insulin producing capacity. That’s when diabetes develops, when impaired pancreatic insulin production can no longer keep up with the demands put on it.

(Interesting but unanswered question: If oxidative injury leads to beta cell dysfunction and destruction, can antioxidants prevent such injury? Studies in cell preparations and animals suggest that anti-oxidative agents, such as astaxanthin and acetylcysteine, may block beta cell oxidative injury. However, no human studies have yet been performed. This may prove to be a fascinating area for future.)

Now that 50% of American have diabetes or pre-diabetes, how much should we blame on eating habits when we were younger? I would wager that eating habits of youth play a large part in determining potential for diabetes or pre-diabetes as an adult.

The lesson: Don’t allow children to repeat our mistakes. Letting them indulge in a lifestyle of soft drinks, candy, pretzels, and other processed junk carbohydrates has the potential to cause diabetes 20 or 30 years later, shortening their life by 10 years. Kids are not impervious to the effects of high sugar, including the cumulative damaging effects of glucose toxicity.