High-protein, reduced-carbohydrate weight-loss diets promote adverse colonic profile

[ben 21]

low carb diets dont sit well with me. carb cycling is much better and alot safer. in fact calorie cycling in general is very effective it keeps your metobolic rate reving and its easy to stay on track. in my opinion a balanced diet is the way to go. yes fat has twice the energy of protein and carbs but your bodys prefered source of energy is carbohydrates. clarance bass had pretty much an all carb diet and in 1983 brought his bodyfat down to 1%. i may be going off the point but thats what i wanted to say. 30g of carbs a day is just silly. (my opinion so keep your hair on)

[NU_nutrition_TS]

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...but your bodys prefered source of energy is carbohydrates. (my opinion so keep your hair on)

Hair is firmly on but that is only true if carbohydrate is all you feed your body - many (if not most) cells and organs preferentially* use fatty acids for energy - when their availability is not blocked by excessive carb ingestion!

*Poor use of words, really, as 'preference' infers a conscious choice and most metabolic processes go on without any conscious direction!

[hailtotheking]

Low-carb commentator Lucas Tafur has some interesting ideas about this issue:

Lucas Tafur: butyrate

[hailtotheking]

Melissa McEwan discussing her take on this issue

Short Chain Fatty Acids and Low-Carb | Hunt.Gather.Love.

Why Paleo didn't fix my IBS | Hunt.Gather.Love.

[NU_nutrition_TS]

It's interesting reading other people's experience with paleo, low carb or, more specifically, low-carb paleo.

I don't see that you have to have a large amount of any carbohydrate/fibre in order to get butyrate or butyric acid. It seems to me this is a rather 'second-hand' solution. Why not get it directly by eating foods rich in butyrate? Butter is the obvious choice but a lot of other dairy products contain it - nutritiondata.com's nutrient search tool can generate a whole list in descending order of content per 100g:

Foods highest in 4:00 in Dairy and Egg Products

Of course, this is assuming you do not have dairy intolerances (though the most common - lactose intolerance - may not be an issue with some of the cheeses, which can have low to zero lactose content).

I think the problem is that a lot of people embarking on a paleo diet do so after reading Loren Cordain's works. He was very much 'anti' saturated fat (you have to eat foods rich in saturated fats, like butter, to get butyrate) to the point that he advised people to eat only the leanest grass-fed meat but slather it in flax oil before cooking it.

Also, the paleo dietary philosophy in general forbids dairy along with legumes and grains. This falls under the 're-enactment fallacy' where people believe they actually have to exactly duplicate a palaeolithic diet to the nth degree instead of using the principles inherent in the palaeolithic diet and apply them with the (natural, whole) foods available today.

Similarly many low carb diet authors are similarly 'anti' saturated fats and tend to advise mono and poly fats or substitution of protein for carbs with fats still at the level advised by the mainstream nutritional dogma.

In response to Melissa McEwen's observations regarding some of her IBS/digestive symptoms: The fact that she often felt as though she had not completely voided her bowel when going to the toilet and then experiencing bouts of diarrhoea, sounds like it could possibly be a case of fecal impaction higher up the rectum/bowel. Often you can experience 'leakage' of watery stools from higher up that makes it seem as if you alternate between constipation and diarrhoea. I would argue lots of fibre is more likely to exacerbate this kind of blockage in the longer term.

[hailtotheking]

One problem i see with just increasing direct dietary sources of butyric acid (e.g. butter or cheese) is there isn't much evidence to suggest any of the butyrate actually makes it to the colon.

Another option that is hinted at by Lucas Tarfur would be to increase consumption of foods with bifidobacteria, like yoghurt or possibly other fermented foods that contain this strain of bacteria.

[NU_nutrition_TS]

I had Lucas Tafur's observations in mind when I posted that:

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The results of these studies show a clear trend: carbohydrate intake and levels of butyrate correlate directly. Ergo, it is assumed that a healthy diet must have a good amount of starch/glucose and non-digestible polysaccharides to produce butyrate and promote colon health.

In my opinion, the interpretation is backwards. Considering the effects of butyrate on colon health, increasing the number of gut bacteria capable of fermenting carbohydrates and producing butyrate is an evolutionary adaptation to a lack of dietary butyrate.

Eating a high fat diet with more butyrate (specially from butter and full fat dairy) decreases the need for species which produce butyrate. Most butyrate (approximately 85%) is absorbed in the gut, so fecal samples may not be a good indicator of overall butyrate levels in the colon. At least not the butyrate that matters. It must be kept in mind that the content of other SCFA (such as propionate and acetate) is also important.

Lucas Tafur: Gut flora

So then the question becomes "does the butyrate need to reach the colon"? Apparently butyrate is a prime energy substrate for colonocytes but do they actually need to be in direct contact with it in order metabolise it as an energy source? My understanding was that butyrate, produced via the fermentation of indigestible fibre by gut bacteria, was absorbed via the distal colon and taken up by the rest of the body and transported to where needed, like any other fatty acid in the general circulation. So surely dietary sources of butyrate - even if absorbed higher up in the gut - would also enter the general circulation where they could be delivered to any other cell that requires it, including the colonocytes?

Certainly studies that have looked at butyrate produced by bacterial fermentation of indigestible fibre, as a factor in colonic health/cancer prevention, have had very inconsistent results.