Fiber!?!

[Dillman]

Alright Jordan,
What is the deal with fiber. It seems like one of those things that the mainstream health crowd wants us to believe is vital to health (like whole grains, low fat diets, bla bla bla). I see that you often suggest 30g fiber/day. Why is that? You are a smart dude and you generally have solid and sound reasons behind your recommendations.

I can't imagine getting that much fiber without supplementation. To me if you can't get a particular nutrient from normal food consumption it deserves more thought/analysis on its importance. I don't get that much fiber and I poop just fine. I supplemented psyllium husk fiber for a while and it seemed to plug me up more.

So please enlighten me on the virtues of 30g fiber/day (please include references, you know you are into that stuff).

[Jordan Feigenbaum]

Alright Jordan,
What is the deal with fiber. It seems like one of those things that the mainstream health crowd wants us to believe is vital to health (like whole grains, low fat diets, bla bla bla). I see that you often suggest 30g fiber/day. Why is that? You are a smart dude and you generally have solid and sound reasons behind your recommendations.

I can't imagine getting that much fiber without supplementation. To me if you can't get a particular nutrient from normal food consumption it deserves more thought/analysis on its importance. I don't get that much fiber and I poop just fine. I supplemented psyllium husk fiber for a while and it seemed to plug me up more.

So please enlighten me on the virtues of 30g fiber/day (please include references, you know you are into that stuff).

First, you don't "need" fiber to live, just like you don't "need" carbohydrates to live. You could be just fine living off an all meat diet (provided the meat had good levels of fat in it).

30g of fiber a day is easily accomplished with a copious supply of sweet potatoes (3g per serving), oats (4g per serving), veggies (~2g per serving), etc. I don't usually take any fiber supplements, unless I'm on the road for extended periods of time...but that's another story.

The idea behind 30g of fiber a day is it makes people improve their food quality, glycemic index, and develop decent eating habits, in my opinion. Think about it, if I'm telling you to eat 200g of carbs a day, but put no fiber minimum in your plan, then literally you "could" eat 200g of carbs from swedish fish, like a boss.

On the other hand, if I said you can eat 200g of carbs a day from anything you want just as long as you get 30g of fiber a day (and you have to count the fiber), it lowers your total carbohydrate count to 170, decreases your calorie intake (since when/if fiber is metabolized you get ~2cal of short chain fatty acids produced in the large bowel), and decreases the amount of trash you can eat while still being compliant.

I don't think you need fiber to be healthy, although some studies would disagree (I would argue this is more correlation-based, not causative). Basically, with a minimum fiber intake like 30g, I can lower calories, force someone to eat their veggies, improve compliance, and keep them regular (which can be a problem whilst dieting).

[Dillman]

1) Excellent! Makes total sense.

2)why don't you back the negativity off of the swedish fish man. The finest candy ever invented deserves a little more respect.

[Jordan Feigenbaum]

1) Excellent! Makes total sense.

2)why don't you back the negativity off of the swedish fish man. The finest candy ever invented deserves a little more respect.

Gotta be careful with the Swedish fish, only use them for carb side-loading (never back load them)!

[tzanghi]

Jordan, I heard in a few of Kiefer's pieces that eating fiber with a meal can cause you to lose up to ~20% of calories that came from the meal. Any merit to this claim?

[Jordan Feigenbaum]

Jordan, I heard in a few of Kiefer's pieces that eating fiber with a meal can cause you to lose up to ~20% of calories that came from the meal. Any merit to this claim?

Not that I'm aware of. If there's a paper out on this, I haven't seen it yet. Fiber generally yields about 2-3kCal per 1g in the form of a short chain fatty acid (butyric acid). It slows down absorption considerably and binds to bile salts, but whether or not this transient decrease in bile salts decreases the emulsification and formation of micelles in the small bowel is unknown to me. I would think this is not true, especially since the contents of the GI system are moving even slower with a high fiber content...

[tzanghi]

Not that I'm aware of. If there's a paper out on this, I haven't seen it yet. Fiber generally yields about 2-3kCal per 1g in the form of a short chain fatty acid (butyric acid). It slows down absorption considerably and binds to bile salts, but whether or not this transient decrease in bile salts decreases the emulsification and formation of micelles in the small bowel is unknown to me. I would think this is not true, especially since the contents of the GI system are moving even slower with a high fiber content...

I figured it was too good to be true haha. Plus it doesn't make sense intuitively because, as you say, fiber slows down digestion.

Is all fiber good for you? The government guidelines seem to say so, but obviously they're not usually right. I've heard that some kinds are good(cruciferous veggies), while some are bad(wheat), is that correct?

[Jordan Feigenbaum]

I don't think any fiber is "good" for you, in the sense that it in and of itself is going to make you healthy or healthier or that you can't live without it (you'll be just fine without it). I'd also have a hard time making a case for a certain type of fiber (soluble vs insoluble, vegetable gums vs inulins, etc.). I think the biggest determinant to how you feel is going to be dependent on where the fiber is coming from, i.e. vegetables or bread, and what you believe that carbohydrate source is going to do to you. If you think you have a food allergy, chances are you're going to be apprehensive about eating that food and maybe you'll feel a "reaction", which may or may not be legitimate. That all be said, mainly as a disclaimer for other nutrition 'experts', I'd prefer most fiber coming from veggies, oats, rice, potatoes, nut butters, fruit, or pysliium husk powder if necessary.

Like I said above, I like fiber and recommend a certain level to achieve a few "other" parameters in the nutrition plan. Make no bones about it though, you'll be fine without it.

[tzanghi]

Gracias, Senor. I think it was a Dave Asprey podcast I heard that wheat fiber was bad on; probably not the best source to go on lol.

[Jordan Feigenbaum]

I tend to think that wheat (not necessarily it's fiber) is not the best source of carbohydrates, but that's another can o' worms.