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Think Twice Before Using Dr Oz Recommended White Kidney Bean Extract

I received an email this week from a client who wanted my input regarding a supplement recommended by Dr Oz. In one of his recent shows, Dr Oz revealed some of his favorite metabolism boosters including the supplement of our discussion, white kidney bean extract.

In this post, I’ll explain what white kidney bean extract does in the human body and my position on it as a weight loss aid.

Now before we even get into whether or not to consider taking white kidney bean extract, I think it’s interesting that Dr. Oz considers this product a “metabolism booster.” We can debate the effectiveness of the extract, but it by no means has ANY impact on raising metabolic rate.

That’s what we’d expect from a “metabolism booster,” right? This supplement has NOTHING to do with metabolic rate and everything to do with blocking the digestion of starches.

Here’s the lowdown on how it white kidney bean extract works…

When you eat starches, otherwise known as complex carbohydrates, the digestion actually starts in your mouth before the food ever gets to your stomach and then to the small intestine.

In fact, starch carbohydrates are mainly digested in the mouth and small intestines. Once the starch enters the stomach, the digestive enzyme used to break it down is destroyed by the high pH levels in the stomach.

More on that in a minute.

When you start chewing a starch carbohydrate like a potato, pasta, legume, grain, etc, the salivary glands in your mouth secrete the digestive enzyme alpha-amylase (also known as ptyalin), to begin hydrolyzing the starch into simple sugars.

This is why if you chew on a piece of bread and leave it in your mouth you’ll get a sweet taste. That’s the starch being broken down to sugar by alpha-amylase.

Anyways, you get the picture with digestion starting in your mouth with the break down of starches. From there the food enters your stomach where starch digestion is temporarily halted. That’s because the highly acidic environment of the stomach neutralizes alpha-amylase like previously mentioned.

As the food moves on to the small intestine (now referred to as chyme), it starts undergoing more digestion. While the highly acid state of the stomach briefly neutralized alpha-amylase, the pancreas can secrete it’s own supply which it now sends to the small intestine to do it’s job breaking down the starch to simple sugars the body can use.

So now that you understand how starch digestion works, let’s look at where white kidney bean extract comes in.

The active ingredient in white kidney bean extract is something called “phaseolus vulgaris” which interferes with the pancreas’s ability to secret alpha-amylase. In other words, it’s blocking the enzyme necessary for starch digestion.

The theory is the starch will then pass through the digestive tract intact without being broken down into simple sugars and possibly later being stored as fat.

Sounds like a miracle product that would allow us to eat all the carbs we want without ever getting fat, right?

Not so fast.

My biggest problem with this supplement is that it gives people faulty expectations. Sure you may be able to block some starch digestion, but is that really a good thing?

Blocking carbohydrate digestion = blocking nutrient assimilation

We shouldn’t be looking for a pill or supplement to STOP the digestion of foods that we’re eating for fuel and nutrients. This is completely counter-intuitive. You should be eating the starch for the nutrients and energy it provides your body.

Block the digestion of starch and you fail to get the valuable nutrients, antioxidants, vitamins and mineral from the food you just consumed.

Why take a bunch of pills or powder to turn life giving food into nothing more than a mass of metabolic waste to be excreted without benefit to your body?

And don’t think there may not be repurcussions with sending all this blocked starch to your large intestine without being digested the way your body is designed to work.

Possible “not so pleasant” side effects of using white kidney bean extract to block starch digestion…

Here’s an excerpt I found regarding the possible side effects of white kidney bean extract while doing my research.

Christine Gerbstadt, MD, RD, cites side effects and a lack of widespread studies as the reason why she doesn’t recommend using starch blockers.

Regarding side effects she tells WebMD white kidney bean extract may block starches from digestion in the small intestine, “But when they get to the large intestine, the starches ferment, give off gas, and cause bloating and diarrhea,” Gerbstadt tells WebMD. Reference to source article.

What the research shows us about white kidney bean extract and possible weight loss benefits…

A study, published in the Internal Journal of Medical Science, conducted a double-blind, placebo-controlled study, in which 60 slightly overweight people were given either placebo or Phase 2, a highly concentrated phaseolus extract, once daily.

This single daily dose was given 30 minutes prior to a large meal rich in carbohydrates.  Over the 30 days of the study, subjects receiving Phaseolus vulgaris extract had significantly greater reduction of body weight, BMI, fat mass, adipose tissue thickness, and waist/hip/ thigh circumferences while maintaining lean body mass compared to subjects receiving placebo.

Additional research of note:

Layer, P., et al. “Effect of purified amylase inhibitor on carbohydrate tolerance in normal subjects and patients with diabetes mellitus.” MAYO Clinic Proceedings 61, 6 (June, 1986) 442-447.

Brugge, W.R. and M. S. Rosenfeld. “Impairment of starch absorption by a potent amylase inhibitor.” American Journal of Gastroenterology 82, 8 (August, 1987) 718-722.

Layer, P., et al. “Effects of decreasing intra luminal amylase on starch digestion and postprandial gastrointestinal function in humans.” On carbohydrate tolerance in normal subjects and patients with diabetes mellitus.” Gastroenterology 91, 1 (July, 1986) 41-48.

Not all white kidney bean extract supplements are proven to be effective at blocking starch…

It’ important to note that to my knowledge only one particular brand of white kidney bean extract has research to prove it’s effectiveness. The brand in reference is called “Phase 2” by Pharmachem Laboratories.

Here’s the thing…according to Mayo Clinic’s research, it would take about 4000 to 6000mg of the extract to effectively inhibit digestion of the starch. The reality is many of the carb blocks being sold don’t contain even the minimum of amount of phaseolamin at 4000mg.

The Phase 2 product is basically a better variant of the phaseolamin (don’t know what they’ve done to the compound), but it’s been shown in clinical trials to be significantly more effective at blocking starch digestion.

I’m not going to go so far as Dr. Oz by giving a blanket endorsement on the use of white kidney extract, but I will say that if you were to take it, the Phase 2 product would be the way to go for the above referenced reasons.

I would not go cheap or buy just any old product off the drug store shelves. Once again quality is extremely important in any nutritional supplement.

What Dr. Oz has to say about white kidney bean extract…

Like I mentioned earlier, this whole subject came up because a client asked me my opinion on it after hearing Dr. Oz recommend the product on his show.

Here’s a link to a video segment of this show from his website. Watch video.

It’s suffice to say that Dr. Oz and his counterpart Lisa Lynn both feel this is a beneficial weight loss aid for individuals to consider.

Here’s an excerpt from his website:

Metabolic-Boosting White Kidney Bean Extract

This ingredient is a known carb blocker and works great for those “off” eating days. Taken along with a high-carb, high-fat meal, white kidney bean extract will block those unwanted calories from being stored as fat. It will also keep your blood sugar balanced. Aim for 300-500 mg two times a day with meals.

At this point it’s fair to say that there’s some compelling evidence that shows white bean extract has the ability to block starch digestion and therefore can help reduce fat spillover from extra starches and their broken down sugars being deposited as body fat.

But is that necessarily a good thing?

I guess that depends how you look at things. I have the utmost respect for Dr. Oz and in full disclosure agree with the majority of what he advocates. I can see his reasoning and don’t discredit the claims on white bean extract being effective at blocking starch digestion.

However, there are some bigger points to consider here…

For starters, look at the language that’s used on his own website. I’m paraphrasing from above…


“The ingredient works great on those “off” eating days. Taken along with a high-carb, high-fat meal, white kidney bean extract will block those unwanted calories from being stored as fat.”

This kinda promotes the idea that this supplement will help you effectively incorporate cheat days and splurge meals and not gain weight.

I for one endorse “re-feed” days but not in this way. I believe there’s merit to increasing starch consumption on occasion while dieting to help boost back up leptin levels and raise metabolism. But this won’t happen if you’re blocking all the starch from being digested.

Giving the green light to take some pill or supplement and everything will go well with your pizza binge is bad advice.

For one thing, let’s be perfectly clear on something…white kidney bean extract does NOT block the absorption of fats. You eat a meal high in starches and fats (say like pizza) and while you can play a metabolic trick blocking the starch digestion, you’re still going to have the issue with excess dietary fat being  stored as body fat.

The bottom line…

While I don’t want to dismiss this product as being effective at blocking starch digestion, I guess I’m not a fan of using it as an aid to get away with eating excess carbs.

This doesn’t provide a solid long-term plan for success. Sure many people will benefit from restricting starch consumption while dieting for weight loss, but those who fare well by bringing them back in on occasion will want all the nutrition and energy benefits.

In short, promoting the idea of taking some pill two times a day with meals to block carbs and thereby help you lose weight, doesn’t sit well with me.

How about just not eating the excess starches all the time? This is one of the reasons why I’m such a big proponent of a Primal Blueprint Diet. While not a “diet” per say, it’s a way of eating that minimizes excess starches in the diet.

Personally, I’m not 100% Primal all the time because my body does well when I incorporate starches on occasion. The idea though is to manipulate your carbohydrate intake naturally by using rotations or cycles in your diet, not by taking some pill to block their absorption.

I think nutrition and fitness expert Phil Kaplan says it best here…

“Does it work? I’d have to say . . . it might. But I’d have to follow the tentative assertion of possible efficacy with the question, “what do you mean by “work?”

It is not a weight loss panacea. It doesn’t affect stored bodyfat. In fact, it doesn’t have any effect on existing body composition. At best, it can limit insulin spikes resultant from starch intake.

My concern with these products is the marketing tends to suggest you can “eat all the carbs you want,” and a pill will neutralize them. I find it far more effective to teach people to ingest the nutrients they need, to limit glucose intake and the resultant insulin spike, and to exercise for optimal use of ingested nutrients.

Phase 2 might have some promise, but I don’t believe it’s going to prove to be of great value in and of itself for those seeking to shed the pounds. It absolutely is not an excuse for a lack of control or nutritional discipline.” Reference to quote.

I believe he hits the nail on the head. It’s all part of the bigger picture with your successful long-term management of a healthy body weight.

I find no reason to warn against the use of white kidney bean extract out of safety concerns, but it’s more about why you’re using it in the first place.

An effective long-term eating plan doesn’t need supplements to block nutrient absorption and play metabolic tricks. You provide your body with the fuel and nutrients it needs, when it needs them, in part of a naturally fluctuating diet.

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The big take away is this product will do nothing to increase your metabolic rate or help you be more efficient at losing existing body fat. It may prevent excess weight from being gained during splurges, but a “metabolism booster” it’s not.

Only you can decide if this product is right for you. As for me I’ll continue coaching and teaching dietary practices that allow the body to release stored fat through carb cycling and NOT carb blocking.

Shane Doll is a certified personal trainer, fat loss expert, speaker, and founder of Shaping Concepts Fitness Training Studios. If you’re looking for a personal trainer in Charleston, you can receive a no-obligations personal training trial and consultation without risking a dime. Over 1000 Charleston area residents have transformed their bodies following our unique burst training workouts and simplified nutrition programs. Experience the Shaping Concepts difference today.

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Category: Supplements.