Category Archives: Dietary Carbohydrate

Fermentable Carbohydrates May Cause or Aggravate Irritable Bowel Sydrome

"Dr. Parker, what can I do about these severe belly cramps?"

“Dr. Parker, what can I do about these severe belly cramps?”

Irritable bowel syndrome (IBS) is one of the conditions that allegedly improves with a paleo diet. It’s frustrating for sufferers and their doctors. My ears perk up when I hear about a new treatment.       

Four weeks of fermentable carbohydrate restriction reduces symptoms of irritable bowel syndrome, according to UK and Australian researchers.

Here’s the theory of how it works.  Our intestines—colon, mostly—are loaded with bacteria.  The food you feed your bacteria—fermentable carbohydrates, for example—may have an effect on the bacteria.  Changes in bacterial populations in response to feeding, in turn, may lead to changes in irritable bowel syndrome and other aspects of health.  This “gut microbiome” is a hot area of research and speculation.

I don’t have irritable bowel syndrome (IBS), but did notice a major decrease in gastrointestinal gas production when I reduced my digestible carbohydrate consumption to less than 50 g/day a few years ago. That alone has at least potential to reduce IBS symptoms. (I eat more than 50 g a day now.)

IBS is extremely common, affecting 10–15% of individuals in the developed world.  Only 15% of those bother to seek medical attention.   Of all referrals to gastroenterologists (stomach specialists), at least 25% are for IBS.  There are few reliable treatments and cures.  In some cases it mysteriously resolves on its own.

So I got excited when I ran across the study I reference above.  I’m not going to spend a lot of time on it because I’ve already spent too much trudging through the article, and I don’t have much to show for it.

The way the investigators wrote their report gave me some heartburn:

  • They never bothered to define “fermentable.”  In this context it probably refers to digestion or breakdown of food by gut bacteria rather than by human hosts.
  • They never bother to spell out exactly what foods the experimental subjects were eating as they restricted fermentable carbohydrate consumption.
  • The intervention group (n=19) was instructed to restrict foods “high in fructans (e.g., wheat products, onions), galacto-oligosaccharide (e.g., legumes), polyols (e.g., pear, sugar-free gums), lactose (e.g., mammalian milk), and excess fructose (e.g., honey).”  Does “restrict” mean “cut back a little” or “avoid entirely upon penalty of death”?  Your guess is as good as mine.  (It’s a joke—I know they wouldn’t kill’em.) Some of the aforementioned foods are restricted or forbidden on the paleo diet.

Have you heard of FODMAPs?  That seems to be the intervention diet that restricted fermentable carbohydrates. FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols.

You need a break. Enjoy.

You need a break. Enjoy.

Let me summarize their results simply by saying they found changes in gut bacteria and a reduction in irritable bowel syndrome symptoms, as compared with control subjects. The particularly responsive symptoms were bloating, borborygmi, and the urge to defecate. Abdominal pain strongly tended to improve but didn’t quite reach statistical significance. Diarrhea wasn’t affected. Also note that the IBS patients allowed into the study were not the type with constipation as a major issue.

So What? 

If you want to try a FODMAP diet for your IBS, you won’t be able to figure out what to eat based on this report. Consult your own physician about it.  I wonder whether many of them have even heard of FODMAP. Barbara Bolen, Ph.D., at About.com says the diet should be undertaken only with the supervision of a qualified nutritionist.

BTW, I’m not aware of any scientific reports looking at the paleo diet as a treatment for IBS. If it works for you, stick with it.

Steve Parker, M.D.

Reference:  Staudacher, Heidi, et al.  Fermentable Carbohydrate Restriction Reduces Luminal Bifidobacteria and Gastrointestinal Symptoms in Patients with Irritable Bowel Syndrome.  Journal of Nutrition, 142: 1520-1518 (2012)

Potential Problems With Severe Carbohydrate Restriction

VERY-LOW-CARB  EATING

First, let’s talk about ketogenic diets, which require reduction of digestible carbohydrates to 50 grams a day or less for most folks.  The iconic ketogenic diet is the induction phase of the Atkins diet, which restricts carbs to a max of 20 g daily.  Note that the average American eats 250 to 300 grams of carb daily.

Your body gets nearly all its energy either from fats, or from carbohydrates like glucose and glycogen. In people eating normally, 60% of their energy at rest comes from fats. In a ketogenic diet, the carbohydrate content of the diet is so low that the body has to break down even more of its fat to supply energy needed by most tissues. Fat breakdown generates ketone bodies in the bloodstream. Hence, “ketogenic diet.” Also called “very-low-carb diets,” ketogenic diets have been around for over a hundred years.

WHAT COULD GO WRONG EARLY ON?

Very-low-carb ketogenic diets have been associated with headaches, bad breath, easy bruising, nausea, fatigue, aching, muscle cramps, constipation, gout attacks, and dizziness, among other symptoms. “Induction flu” may occur around days two through five, consisting of achiness, easy fatigue, and low energy. It clears up after a few days.

Other effects that you might not even notice immediately (if ever) are low blood pressure, high uric acid in the blood, excessive loss of sodium and potassium in the urine, worsening of kidney disease, deficiency of calcium and vitamins A, B, C, and D, among other adverse effects.

A well-designed ketogenic diet should address all these potential issues.  My Ketogenic Mediterranean Diet is an example.  I followed it for for six months and blogged about it.  (The KMD is not a paleo diet.)

Athletic individuals who perform vigorous exercise should expect a deterioration in performance levels during the first three to four weeks of any ketogenic very-low-carb diet. The body needs that time to adjust to burning mostly fat for fuel rather than carbohydrate.

Competitive weight-lifters or other anaerobic athletes (e.g., sprinters) will be hampered by the low muscle glycogen stores that accompany ketogenic diets. They need more carbohydrates.

WHAT ABOUT THE LONG RUN?

Long-term effects of a very-low-carb or ketogenic diet in most people are unclear—they may have better or worse overall health—we just don’t know for sure yet. Perhaps some people gain a clear benefit, while others—with different metabolisms and genetic make-up—are worse off.

If the diet results in major weight loss that lasts, we may see longer lifespan, less type 2 diabetes, less cancer, less heart disease, less high blood pressure, and fewer of the other obesity-related medical conditions.

Ketogenic diets are generally higher in protein, total fat, saturated fat, and cholesterol than some other diets. Some authorities are concerned this may increase the risk of coronary heart disease and stroke; the latest evidence indicates otherwise.

Some authorities worry that ketogenic diets have the potential to cause kidney stones, osteoporosis (thin, brittle bones), gout, deficiency of vitamins and minerals, and may worsen existing kidney disease. Others disagree.

It’s clear that compliance with very-low-carb diets is difficult to maintain for six to 12 months. Many folks can’t do it for more than a couple weeks. Potential long-term effects, therefore, haven’t come into play for most users. When used for weight loss, regain of lost weight is a problem (but regain is a major issue with all weight-loss programs). I anticipate that the majority of non-diabetics who try a ketogenic diet will stay on it for only one to six months. After that, more carbohydrates can be added to gain the potential long-term benefits of additional fruits and vegetables.

Or not.

People with type 2 diabetes or prediabetes may be so pleased with the metabolic effects of a ketogenic diet that they’ll stay on it long-term.

Steve Parker, M.D.

 

Do Tomatoes Have Too Many Carbohydrates?

Eat greens for vitamin K

Looks reasonable to me

Dr. Richard Bernstein wrote a great book advocating strict carbohydrate restriction for folks with diabetes.  I’m talking about a max of 30 grams a day, compared to 250–300 g in the standard American diet.

Dr. Bernstein cautions his diabetic patients and readers of Diabetes Solution to keep a tight lid on consumption of tomatoes.  An excerpt from page 149:

If you have them uncooked in salad, limit yourself to one slice or a single cherry tomato per cup of salad.

His concern is that tomatoes will raise your blood sugar too high.

That doesn’t make sense to me.  A 3-inch diameter tomato has 7 grams of carbohydrate, 2 of which are fiber.  So the digestible carb count is only 5 grams.  That’s not much.  So do tomatoes have a high glycemic index?  Unlikely, although it’s hard to be sure.  Good luck finding a reliable GI for tomatoes on the Internet.

I think Dr. Bernstein’s wrong about this one, which is rare.  I suppose it’s possible that tomatoes deliver some other substance to the bloodstream that interferes with carbohydrate metabolism, but Dr. Bernstein doesn’t mention that.

Do tomatoes play havoc with your blood sugars?

Steve Parker, M.D.

Low-Carb Research Update

Grain-based high-carb Neolithic food

Grain-based high-carb Neolithic food

The paleo diet averages about 30% of total calories from carbohydrates, with a range of about 22 to 40%.  That 30% average is much lower than the standard 50–60% in the developed world.  Is that lower percentage healthy or not?  It depends on the quality of the carbs and the remainder of the diet.  It most certainly can be healthy.

As much as possible, I base my nutrition and medical recommendations on science-based research published in the medical literature.  In the early 2000s, a flurry of scientific reports demonstrated that very-low-carb eating (as in the style of Dr. Robert Atkins) was safe and effective for short-term weight management and control of diabetes.  Eighty hours of literature review in 2009 allowed me to embrace low-carbohydrate eating as a logical and viable option for many of my patients. The evidence convinced me that the relatively high fat content of many low-carb diets was nothing to worry about long-term.

I’d like to share with you some of the pertinent low-carb research findings of the last few years.

Low-Carb Diets

  • Low-carb diets reduce weight, reduce blood pressure, lower triglyceride levels (a healtlhy move), and raise HDL cholesterol (another good trend).  These improvements should help reduce your risk of heart disease.  (In the journal Obesity Reviews, 2012.)
  • Dietary fat, including saturated fat, is not a cause of vascular disease such as heart attacks and atherosclerosis (hardening of the arteries).  (Multiple research reports.)
  • If you’re overweight and replace two sugary drinks a day with diet soda or water, you’ll lose about four pounds over the next six months.  (American Journal of Clinical Nutrition, 2012.)
  • United States citizens obtain 40% of total calories from grains and added sugars.  Most developed countries are similar.  Dr. Stephan Guyenet notes that U.S. sugar consumption increased steadily “…from 6.3 pounds [2.9 kg] per person per year in 1822 to 107.7 pounds [50 kg] per person in 1999.  Wrap your brain around this: in 1822 we ate the amount of added sugar in one 12-ounce can of soda every five days, while today we eat that much sugar every seven hours.”
  • A very-low-carb diet improves the memory of those with age-related mild cognitive impairment. Mild cognitive impairment is a precursor to dementia.  (University of Cincinnati, 2012.)
  • High-carbohydrate and sugar-rich diets greatly raise the risk of mild cognitive impairment in the elderly. (Mayo Clinic study published in the Journal of Alzheimers’ Disease, 2012.)
  • Compared to obese low-fat dieters, low-carb dieters lose twice as much fat weight.  (University of Cincinnati, 2011.)
  • Diets low in sugar and refined starches are linked to lower risk of age-related macular degeneration in women.  Macular degeneration is a major cause of blindness.  (University of Wisconsin, 2011.)
  • A ketogenic (very-low-carb) Mediterranean diet cures metabolic syndrome (Journal of Medicinal Food, 2011.)
  • For type 2 diabetics, replacing a daily muffin (high-carb) with two ounces (60 g) of nuts (low-carb) improves blood sugar control and reduces LDL cholesterol (the “bad” cholesterol). (Diabetes Care, 2011.)
  • For those afflicted with fatty liver, a low-carb diet beats a low-fat diet for management. (American Journal of Clinical Nutrition, 2011.)
  • For weight loss, the American Diabetes Association has endorsed low-carb (under 130 g/day) and Mediterranean diets, for use up to two years. (Diabetes Care, 2011.)
  • High-carbohydrate eating doubles the risk of heart disease (coronary artery disease) in women.  (Archives of Internal Medicine, 2010.)
  • One criticism of low-carb diets is that they may be high in protein, which in turn may cause bone thinning (osteoporosis).  A 2010 study shows this is not a problem, at least in women.  Men were not studied.  (American Journal of Clinical Nutrition.)
  • High-carbohydrate eating increases the risk of developing type 2 diabetes (American Journal of Clinical Nutrition, 2010.)
  • Obesity in U.S. children tripled from 1980 to 2000, rising to 17% of all children.  A low-carb, high-protein diet is safe and effective for obese adolescents.  (American Journal of Clinical Nutrition, 2010.

Steve Parker, M.D.

PS:  The paleo diet is also referred to as the caveman diet, Paleolithic diet, hunter-gatherer diet, Stone Age diet, and ancestral diet.

Are You Afraid of the Night(shades)?

Rosemary Chicken (garnished with pico de gallo) and Rosemary Potatoes

Rosemary Chicken (garnished with pico de gallo) and Rosemary Potatoes

The nightshade family includes potatoes (not sweet potatoes or yams), tomatoes, eggplant, peppers, goji berries, and even tobacco.  Anecdotal reports indicate that consumption of these either cause or aggravate certain chronic medical conditions, such as arthritis, chronic fatigue, or irritable bowel syndrome.

Georgia Ede, M.D., has an article on medical effects of nightshades at her website.  The potentially offensive chemicals in nightshades are called glycoalkaloids.  I looked into this issue when deciding whether to include potatoes in my version of the paleo diet.  (They’re included).

Dr. Ede’s writes:

As with any food sensitivity, the only way to find out is to remove nightshades from your diet for a couple of weeks or so to see if you feel better.  There are ZERO scientific articles about nightshade sensitivity, chronic pain, or arthritis in the literature, however, the internet is full of anecdotal reports of people who have found that nightshades aggravate arthritis, fibromyalgia, or other chronic pain syndromes.

I bet I could eat a couple potatoes and tomatoes every day without ill effect.  And there’s Chris Voigt, head of the Washington State Potato Commission, famous for his 60-day potato diet.  As they say, your mileage may vary.

Steve Parker, M.D.

Carbohydrates and Sugar Increase Risk of Elderly Cognitive Impairment

 

How many brain cells with this roll kill?

How many brain cells with this roll kill?

The Mayo Clinic recently reported that diets high in carbohydrates and sugar increase the odds of developing cognitive impairment in the elderly years.

Mild cognitive impairment is often a precursor to incurable dementia.  Many authorities think dementia develops more often in people with diabetes, although some studies refute the linkage.

Researchers followed 940 patients with normal baseline cognitive functioning over the course of four years. Diet was assessed via questionnaire. Study participants were ages 70 to 89. As the years passed, 200 of them developed mild cognitive impairment.

Compared with those eating at the lowest level of carbohydrate consumption, those eating at the highest levels were almost twice as likely to go to develop mild cognitive impairment.

The scientists note that those eating lower on the carbohydrate continuum were eating more fats and proteins.

Steve Parker, M.D.

Denmark’s Paleolithic Diet

ScienceNordic has an article about the diet of Paleolithic humans who lived in what is now Denmark.  It’s brief and written for the general public.  The author mistakenly characterizes the “modern paleo” diet as no- or very-low-carb.  It’s lower in carb content than the standard American diet, but by no means no-carb.

—Steve