Some say we need lots of fiber, some say we don't really need it at all. What's the word on this?
No. Good Calorie, Bad Calorie by Gary Taubes has a good review of fiber. None of the original claims have panned out in studies. The history is very interesting: those studying public health needed a way to explain why indigenous populations were healthy and then became diseased once they ate the foods of civilization. Of course the answer was mostly that flour and sugar are devastating to health, but that wasn't a politically correct answer. Incredibly, the original proponent of the fiber theory had treated the Masai in Africa, who appear to be in great health when they eat their natural diet with very little fiber.
We should also note that the Inuit ate almost 0 plant fiber at certain times of year and were certainly on a low fiber diet. Cases of any cancer in the Inuit (including digestive-related that fiber supposedly prevents) were extraordinarily rare. I believe Taubes mentions this point in a talk about sugar. I have seen people call animal connective tissue a form of fiber, although I wouldn't use that terminology. This is the only "fiber" worth going out of your way to eat in my mind. Our paleo ancestors didn't just eat tender cuts of meat. Stephenson in Fat of the Land stated that the Inuit threw tender cuts to the dogs and said the tougher cuts of meat tasted better, and they ate it by chewing minimally and just swallowing.
Stephen at Whole Health Source blog had some posts bringing forth some causal evidence that fiber can have some limited beneficial effects. One is the creation of butyrate, which you can get from butter. The other was improved gut health from oligofructose. Stephen's claims are different from silly mainstream theories (for example: prevents colon cancer) that have nothing real to back them up as discussed in Good Calorie, Bad Calorie. Fiber can also slow down the absorption of carbohydrates, but of course the better solution is to not eat so many carbohydrates that you require fiber to digest them in a healthy way.
Not need certainly, but then our bodies are flexible, there are lots of thing we don't need- large amounts of animal fats for example, we could mostly just manufacture our own from sweet potato- so the question is whether fibre would be optimal.
Clearly hunter-gatherers have thrived in a wide variety of contexts and for every healthy Inuit you can find a healthy kitavan. It would make sense that a flexible, omnivorous animal like humans would be able to survive without a daily dose of fibre, but be able to do something useful (e.g. butyrate) with it if it is a large part of our diet.
As I mused over here, fibre seems good if you've got a healthy gut flora to do useful things with your fibre (like turn it into fat) and positively harmful if you've got lots of pathogenic bacteria. As Peter notes, eating lots of fibre is basically feeding your digestive bugs, whether this is good depends on the bacteria. As he notes in that series, bacteria can have a huge array of quite scarily profound effects on us, they typically have an interest in keeping us alive, but they might well achieve this by forcing us to store fat, even making us prefer certain foods.
Another possibility is that higher amounts of fibre are desirable if you're eating large amounts of carbohydrate, but neither necessary nor desirable if not. We can perhaps say something similar of vitamin C and such plant-based nutrients, it seems plausible that where humans were reliant on lots of plant material, we'd do best getting the complete package, rather than a processed source of carbohydrate. At kitavan levels of starchy tuber, you might be looking at around 50g fibre per day.
My personal experience is that my digestion was awful one a very high fibre, pre-paleo flax and wheat bran diet, fine on a 0g fibre paleo diet but most comfortably on LC paleo with healthy doses of low carb vegetables. Extremely high fibre is certainyl bad (anti-nutritious) so I'd stick to evolutionarily plausible amounts of fibre. I think relatively high amounts of plant and fibre could be plausible. Not every-one in a community can be hunting animals all the time and whatever the hunter-gatherers are gathering, would likely contain decent amounts of fibre.
Well, we certainly don't need it for what mainstream medicine thinks we need it for. Fiber is NOT the best way to keep things moving. Healthy gut flora will do that.
What fiber DOES provide is a way for our colon to produce short chain fatty acids. Some of these might be beneficial and important. Whole Health Source has a good post about it. Our closest relatives, the great apes, get most of their energy from SCFA. We don't have a big enough colon to do that, but we can still make them.
Personally I feel that fiber is not necessary, but good gut bacterial health is THE KEY. Also, When scientists study the bowel habits of indigenous and 3rd world cultures, they forget that squat pooping is also a key to good bowel health - the composition of a diet can sometimes be a red herring.
If necessary means you will die without it then no, it isn't necessary in that sense.
Soluble fiber is fermented into SCFA by certain (note: not all) gut flora (mostly the beneficial ones) so by 'feeding' them they are able to out-compete the pathogenic flora thereby improving your personal brand of flora.
Having plentiful gut flora proliferated by a significant but reasonable intake of soluble fiber greatly aides in the metabolism and excretion of micro and macro component carcinogens. The flora also synthesize biotin and vitamin K.
SCFA produced by the flora...
For the aforementioned reasons I cannot find any logical purpose to NOT eat a significant but reasonable amount of soluble fiber. It has no known, scientifically proven cons for the average human.
Edit: My idea of ' significant but reasonable is ~10-20 g/day
Fiber and Paleo. You might find a difference of opinions on this one.
*Greens are fibrous and not starchy or calorie dense, so if we add enough back to replace the lost calories, we are eating a huge amount of vegetables now. This is in fact advocated by authors like Colin Campbell and Joel Furhman - it can have some effect as the mechanical satiety and sheer work of eating may reduce your caloric intake. However, you will be having a minimal effect on insulin levels at the expense of eating fewer higher quality animal foods and absurd amounts of fiber - this approach only makes sense if you think animal products and fats per se are unhealthy - they are not. Also you just don't need that many vegetables in general and you don't need "fiber" at all.
I just cut and paste from the related question here: LINK
Been looking at this myself and thought I would add to this old post for people searching in the future.
Dr. Konstantin Monastyrsky.
Fiber Menace: The Truth About the Leading Role of Fiber in Diet Failure, Constipation, Hemorrhoids, Irritable Bowel Syndrome, Ulcerative Colitis, Crohn's Disease, and Colon Cancer: http://www.gutsense.org/fibermenace/about_fm.html
I have spent years trying to make sure I get enough fiber. I think I started with the high fiber thinking to "keep myself fuller longer", which I guess I'm now doing with fat.
I am having a huge mental block on getting past making sure I get 20 grams of fiber per day. I am wondering if there are any new thoughts on this subject.
Fiber and carbs for that matter are not essential for good health. In small quantities (e.g., a few veggies or tubers daily) they are probably not detrimental for most people either.
For me personally, the less fiber I eat the better I feel. My carb/fiber consumption is essentially all from veggies. I believe the carbs and fiber feed pathogenic gut bacteria. To control it, I eat veggies one meal a day every other day or so, and I make a point to have a 16+ hour daily fasting period with no food (e.g., I restrict eating to an 8 or less window each day). I always feel the best when I'm 8+ hours into my fast (I welcome feedback or comments if anyone knows what's going on).