Do dietary lectins cause disease?

I’m lifting this wholesale from the NCBI site because it’s one of the more reliable articles on lectins and as it dates back to 1999, it seems to be mostly off the radar. My emphasis added.

In 1988 a hospital launched a “healthy eating day” in its staff canteen at lunchtime. One dish contained red kidney beans, and 31 portions were served. At 3 pm one of the customers, a surgical registrar, vomited in theatre. Over the next four hours 10 more customers suffered profuse vomiting, some with diarrhoea. All had recovered by next day. No pathogens were isolated from the food, but the beans contained an abnormally high concentration of the lectin phytohaemagglutinin. Lectins are carbohydrate binding proteins present in most plants, especially seeds and tubers like cereals, potatoes, and beans. Until recently their main use was as histology and blood transfusion reagents, but in the past two decades we have realised that many lectins are (a) toxic, inflammatory, or both; (b) resistant to cooking and digestive enzymes; and (c) present in much of our food. It is thus no surprise that they sometimes cause “food poisoning.” But the really disturbing finding came with the discovery in 1989 that some food lectins get past the gut wall and deposit themselves in distant organs. So do they cause real life diseases?This is no academic question because diet is one part of the environment that is manipulable and because lectins have excellent antidotes, at least in vitro. Because of their precise carbohydrate specificities, lectins can be blocked by simple sugars and oligosaccharides. Wheat lectin, for example, is blocked by the sugar N-acetyl glucosamine and its polymers. These natural compounds are potentially exploitable as drugs should lectin induced diseases be identified.

Wheat gliadin, which causes coeliac disease, contains a lectin like substance that binds to human intestinal mucosa, and this has been debated as the “coeliac disease toxin” for over 20 years. But coeliac disease is already managed by gluten avoidance, so nothing would change were the lectin hypothesis proved. On the other hand, wheat lectin also binds to glomerular capillary walls, mesangial cells, and tubules of human kidney and (in rodents) binds IgA and induces IgA mesangial deposits. This suggests that in humans IgA nephropathy might be caused or aggravated by wheat lectin; indeed a trial of gluten avoidance in children with this disease reported reduced proteinuria and immune complex levels.

Of particular interest is the implication for autoimmune diseases. Lectins stimulate class II HLA antigens on cells that do not normally display them, such as pancreatic islet and thyroid cells. The islet cell determinant to which cytotoxic autoantibodies bind in insulin dependent diabetes mellitus is the disaccharide N-acetyl lactosamine, which must bind tomato lectin if present and probably also the lectins of wheat, potato, and peanuts. This would result in islet cells expressing both class II HLA antigens and foreign antigen together—a sitting duck for autoimmune attack. Certain foods (wheat, soya) are indeed diabetogenic in genetically susceptible mice. Insulin dependent diabetes therefore is another potential lectin disease and could possibly be prevented by prophylactic oligosaccharides.

Another suspect lectin disease is rheumatoid arthritis. The normal human IgG molecule possesses carbohydrate side chains, which terminate with galactose. In rheumatoid arthritis much of the galactose is missing, so that the subterminal sugar—N-acetyl glucosamine—is exposed instead. These deficient IgG molecules feature strongly in the circulating immune complexes that cause fever and symptoms. In diet responsive rheumatoid arthritis one of the commonest trigger foods is wheat, and wheat lectin is specific for N-acetyl glucosamine—the sugar that is normally hidden but exposed in rheumatoid arthritis. This suggests that N-acetyl glucosamine oligomers such as chitotetraose (derived from the chitin that forms crustacean shells) might be an effective treatment for diet associated rheumatoid arthritis. Interestingly, the health food trade has already siezed on N-acetyl glucosamine as an antiarthritic supplement.

Among the effects observed in the small intestine of lectin fed rodents is stripping away of the mucous coat to expose naked mucosa and overgrowth of the mucosa by abnormal bacteria and protozoa. Lectins also cause discharge of histamine from gastric mast cells, which stimulates acid secretion. So the three main pathogenic factors for peptic ulcer—acid stimulation, failure of the mucous defence layer, and abnormal bacterial proliferation (Helicobacter pylori) are all theoretically linked to lectins. If true, blocking these effects by oligosaccharides would represent an attractive and more physiological treatment for peptic ulcer than suppressing stomach acid. The mucus stripping effect of lectins also offers an explanation for the anecdotal finding of many allergists that a “stone age diet,” which eliminates most starchy foods and therefore most lectins, protects against common upper respiratory viral infections: without lectins in the throat the nasopharyngeal mucus lining would be more effective as a barrier to viruses.

But if we all eat lectins, why don’t we all get insulin dependent diabetes, rheumatoid arthritis, IgA nephropathy, and peptic ulcers? Partly because of biological variation in the glycoconjugates that coat our cells and partly because these are protected behind a fine screen of sialic acid molecules, attached to the glycoprotein tips. We should be safe. But the sialic acid molecules can be stripped off by the enzyme neuraminidase, present in several micro-organisms such as influenzaviruses and streptococci. This may explain why diabetes and rheumatoid arthritis tend to occur as sequelae of infections. This facilitation of lectins by micro-organisms throws a new light on post-infectious diseases and makes the folklore cure of fasting during a fever seem sensible.

Alternative medicine popularisers are already publishing articles about dietary lectins, often with more enthusiasm than caution, so patients are starting to ask about them and doctors need to be armed with facts. The same comment applies to entrepreneurs at the opposite end of the commercial spectrum. Many lectins are powerful allergens, and prohevein, the principal allergen of rubber latex, is one. It has been engineered into transgenic tomatoes for its fungistatic properties, so we can expect an outbreak of tomato allergy in the near future among latex sensitive individuals. Dr Arpad Pusztai lost his job for publicising concerns of this type (20 February, p 483).

Questioning the Gospel on Breakfast

BreakfastWe’ve seen the headline splashed everywhere this week: Study shows eating breakfast helps teens lose weight.

So now everyone one has jumped on the bandwagon to reiterate mom’s advice that breakfast is the most important meal of the day.

I just don’t buy it.

I’m not convinced that just because the average teen diet is improved by eating breakfast, it means that we all need to get a meal in before 10 am.

Dr Biffa has put forward the case and I accept all his points. Namely:

  1. Caloric restriction can reduce the metabolic rate
  2. Skipping breakfast can make you ravenous later in the day
  3. Skipping breakfast can make you seek out carbs later in the day

All of this: definitely possible. But it strikes me that these are issues for people who are running on glucose and suffer from swings of blood sugar levels.

If you are a high carb consumer, then yes, getting regular small doses is better than the roller coaster ride. And given that the study was done on teens, it’s probably a fair bet to say that their diet was loaded with carbs.

But the analysis that says “if doing X is better than what you are usually doing, then X must be good” is flawed. X might be good but it also might suck as far as all the other viable options go.

Modern Forager takes this kind of thinking apart in his post: So What’s The Real Scoop On Whole Grains?

Yet we’re constantly told that whole grains prevent diabetes, heart disease, cancer, and every other malady under the sun. I will accept that whole grains are better for you than refined grains. That doesn’t really boggle the mind. What does boggle the mind is why all of these studies refuse to pit a whole grains-rich diet against a grain-free, produce-rich hunter-gatherer diet.

Exactly. Better doesn’t mean best. It might not even mean good. And it certainly cannot mean “absolutely best for everyone.”

Which brings me around to breakfast.

There have been many people who have reported good results from intermittent fasting. This is in effect an extreme form of “skipping breakfast.”

For an excellent yes-I-know-this-is-an-anecdote-and-not-research datapoint, read this great account of how skipping breakfast helped Lee Shurie cure his diabetes without meds (he also lost a few pounds in the process):

Upon waking in the morning I tested my sugar levels and found they were typically in the 150 mg/dl range. I expected them to come down by noon, but was surprised that they stayed above normal for quite some time. As the day went on I became worried (and hungry!), but I held off eating until nearly 6 PM, when my blood sugar level was normal. At this point I wanted to eat a huge meal, but I ate a normal dinner instead. As the evening progressed I snacked on healthy, low glycemic foods.

After following this regimen for days, which stretched into weeks, I discovered it provided whole new level of physical energy and mental alertness. After the first few days I was already “un-training” my body of the expectation that food would be provided at set meal intervals. After a week or so I no longer felt hungry until about 4 PM. On some days, I do not get hungry until 7 or 8 PM, but if I do get hungry earlier, I wait until 6 PM to eat. The one exception to this schedule is if I am doing strenuous exercise; I might have a small mid-afternoon snack (an apple or a few nuts).

I suspect that once you have trained your body to work off slow burning ketones instead of fast burning glucose, you do not need to be teathered to the 3-5 meals a day routine. I also suspect that “back in the day” when we were foragers, that skipping breakfast was a regular occurance.

As such, without a bit more compelling evidence, I find the case for the biological imperative weak. Call me cynical.

What about breakfast being the most important meal of the day? This slogan is brough to you by the same system that has helped make 65 percent of Americans overweight; it has helped to sell a lot of breakfast cereal and toaster pastries. You can see for yourself whether you’re better off with breakfast or without it. Put it to the test. – The Fast-5 Diet, pg 28

Of course everyone is different and some people will do better with breakfast. No doubt the average carb junkie is better not skipping meals. But once you’ve got the sugar monkey off your back, there can be a lot of reasons why a diet without breakfast works for you.

The Uninsured Patient

3 Quarks Daily has an interesting report of a man who came close to death due to, in the author’s opinion, failure to medicate properly because of lack of insurance. He was poor but not poor enough to receive Medicaid. He was obese, had type 2 diabetes and without health insurance was attempting to manage his condition through diet instead of meds.

By the time he arrived into the author’s care, he was close to death caused by internal bleeding.

If JD could have afforded it, he would have seen a primary care doctor and controlled his diabetes. If JD had cared, he would have not grown to a mammoth size; his callous eating behavior and the inefficient health system had landed him in this intensive expensive care, which could have been avoided by spending much less on prevention.

Callous eating behavior. Nice touch.

The story is damning of the health care system but I was struck by the author’s ability to give JD a good punch in the gut as well. The automatic assumption that obesity is due to a personality failure is so pervasive that even a trained medical professional with no knowledge of a patient’s eating history will assume it and publicly denounce him for it.

The road to changing the “paradigm” on how we view obesity is certainly a long and slow one.

3 Quarks Daily: The Uninsured Patient

Study: Lowering blood sugar increased risk of death

Back to the drawing boards:

For decades, researchers believed that if people with diabetes lowered their blood sugar to normal levels, they would no longer be at high risk of dying from heart disease. But a major federal study of more than 10,000 middle-aged and older people with Type 2 diabetes has found that lowering blood sugar actually increased their risk of death, researchers reported Wednesday.

More: New York Times

Roundup

Tidbits over the last month worth a mention…

Shake it Baby
In a bizarre experiment, mice were “vibrated” for 15 minutes a day resulting in fat loss and corresponding bone density increases. Can we vibrate those pounds away? Well we had one of those crazy machines in the basement for years and it did nothing for mother…

Vestigial What?
Just last month I had a doctor telling me I should “chop off my appendix” given my history of IBS and “it’s useless anyway.” I was sceptical that mother nature was that inefficient and opted to keep it to the rolling eyes of the specialist. Well ha, ha! HA! Appendix not useless afterall. Seems like it’s a little factory and warehouse of good bacteria. Pwned!

Type 3
Discovery supports theory of Alzheimer’s disease as a form of diabetes. All that sugar is going to your head. Levels of brain insulin and its related receptors are lower in individuals with Alzheimer’s disease.

Finish that Avocado
Monounsaturated Fat Improves Insulin Sensitivity. Eating a diet rich in monounsaturated fat reverses insulin resistance compared to diets rich in carbohydrates or saturated fat.

Big Where it Counts
Big hips mean big brains. Curvy women birthed children with superior cognitive abilities.

Alzheimer’s and Living Low Carb

The Washington Post reports on the correlation between “pre-diabetes” (high blood sugar levels not yet in the diabetic range) and alzheimer’s:

People with elevated blood sugar levels may have an increased risk of developing Alzheimer’s disease, researchers reported yesterday at an international conference. Scientists already have linked Type 2 diabetes with Alzheimer’s, which afflicts 4.5 million Americans.

Full Article

So what can you do to protect yourself? Go low carb of course… well at least according to Dr. Larry McCleary, the author of  The Brain Trust who describes ketones as “the brain’s preferred fuel.”
Via Living La Vida Low Carb 

How I Defeated Type II Diabetes

I great account by a guy who came to indepentantly discover CRON “Calorie Restriction with Optimal Nutrition” – a lifestyle and diet change which effectively cured his type II diabetes (or at least brought it under permanent control) along with a number of other benefits.

http://shurie.com/lee/writing_defeat_diabetes.htm

Paleo Diet and Diabetes

In a head to head competition between the Paleo diet and the Mediterranean diet, Paleo won hands down when it came to glucose tolerance and treating diabetes…

The improved glucose tolerance in the Paleolithic group was unrelated to changes in weight or waist circumference, although waist decreased slightly more in that group. Hence, the research group concludes that something more than caloric intake and weight loss was responsible for the improved handling of dietary carbohydrate. The main difference between the groups was a much lower intake of grains and dairy products and a higher fruit intake in the Paleolithic group. Substances in grains and dairy products have been shown to interfere with the metabolism of carbohydrates and fat in various studies.

“If you want to prevent or treat diabetes type 2, it may be more efficient to avoid some of our modern foods than to count calories or carbohydrate,” says Staffan Lindeberg.

This is the first controlled study of a Paleolithic diet in humans.

Science Daily, June 28 2007

Lowering BP helps those with Type 2

Science keeps plodding along to help save us from ourselves…

While the reduction in blood pressure was modest (an average of 5.6/2.2 mm Hg), at 4.3 years the treated group had a relative risk reduction of 14 percent for coronary heart disease events, 18 percent for cardiovascular deaths, 14 percent for deaths of any cause, and 21 percent for developing new or worsening kidney disease.

MacMahon calculated that one death could be avoided among every 78 patients treated for five years. Because type-2 diabetes is so common worldwide, he added that treatment such as this could prevent as many as 1.5 million deaths, even if given to only half of the world’s diabetics.

I love that they have bothered to report the Numbers Needed to Treat here ie 78 people treated saves 1 life. It’s worth pointing out though that they haven’t prevented 1.5m deaths so much as postponed them! More