14 replies to this topic

[RJ100]

I'd read before that milk interferes with the absorption of catechins from green tea, but this study seems to suggest it’s proteins in general -

Antioxidant activity of blueberry fruit is impaired by association with milk

The first sentence of the abstract:

"The antioxidant properties of dietary phenolics are believed to be reduced in vivo because of their affinity for proteins."

Now I avoid milk and most dairy anyway, but this study seems to indicate it's not just casein that phenols tend to bind to.

I ingest most of my phenolic compounds (green tea, GSE, blueberries, Resv, etc.) either with my BCAA sup or with meals that are, typically, heavily protein. Am I doing it wrong?

[nowayout]

Well, proteins are very efficiently broken down into their constituent amino acids during digestion, which will probably release any phytonutrients that may have stuck to the original whole proteins.

As a species we are the optimized survivors of many famines. I suspect that if human digestion were so inefficient as to waste nutrients just because we eat them in the "wrong" combinations, we probably would have gone extinct long ago.

[RJ100]

It's not "wasting nutrients" - it's chemistry. It's not "wrong combinations" - it's using knowledge to make intelligent combinations.

To that point, the study demonstrates clearly that the blueberry phenols were not well absorbed and were ineffective as antioxidants because they bonded with milk protein during digestion. This has also been shown with milk + green tea.

What I'm asking is if this is an issue with this specific protein (casein) or if phenols tend to link to proteins in general, and would therefor be more bioavailable if they were ingested separately.

[Kevnzworld]

Not with cocoa polyphenols ( chocolate milk ! )
http://onlinelibrary...enticated=false

This is a quote from a long article about polyphenol bioavailability .

Direct interactions between polyphenols and some components of food, such as binding to proteins and polysaccharides, can occur, and these interactions may affect absorption. Furthermore, more indirect effects of the diet on various parameters of gut physiology (pH, intestinal fermentations, biliary excretion, transit time, etc) may have consequences on the absorption of polyphenols. Enzymes and carriers involved in polyphenol absorption and metabolism may also be induced or inhibited by the presence of some micronutrients or xenobiotics. Interactions with milk proteins were considered first because Serafini et al (133) reported that addition of milk to black tea abolished the increase in antioxidant potential that was observed when tea was consumed without milk. However, subsequent studies showed that addition of milk to black or green tea had no effect on the bioavailability of catechins, quercetin, or kaempferol in humans (134, 135

http://ajcn.nutritio...t/79/5/727.full

Edited by Kevnzworld, 26 September 2012 - 08:56 PM.

[nowayout]

I wouldn't pay too much attention to the study in the OP until it has been replicated and better understood. As we see from Kevnzworld's post, it appears that a similar concern for tea was subsequently dismissed by further investigation.

By the way, your blood is full of proteins, and so are your cells... Oh my God!

[RJ100]

Not with cocoa polyphenols ( chocolate milk ! )
http://onlinelibrary...enticated=false

This is a quote from a long article about polyphenol bioavailability .

Direct interactions between polyphenols and some components of food, such as binding to proteins and polysaccharides, can occur, and these interactions may affect absorption. Furthermore, more indirect effects of the diet on various parameters of gut physiology (pH, intestinal fermentations, biliary excretion, transit time, etc) may have consequences on the absorption of polyphenols. Enzymes and carriers involved in polyphenol absorption and metabolism may also be induced or inhibited by the presence of some micronutrients or xenobiotics. Interactions with milk proteins were considered first because Serafini et al (133) reported that addition of milk to black tea abolished the increase in antioxidant potential that was observed when tea was consumed without milk. However, subsequent studies showed that addition of milk to black or green tea had no effect on the bioavailability of catechins, quercetin, or kaempferol in humans (134, 135

http://ajcn.nutritio...t/79/5/727.full

The first sentence from the quote is exactly what I'm asking about.

Direct interactions between polyphenols and some components of food, such as binding to proteins and polysaccharides, can occur, and these interactions may affect absorption.

Interaction of dietary polyphenols with bovine milk proteins: molecular structure-affinity relationship and influencing bioactivity aspects

Interaction of phytochemicals with dairy ingredients

Kevnzworld, do you take your polyphenol stack on an empty stomach or with food?

[nowayout]

The obvious and glaring problem with the blueberry study, for anyone who knows the first thing about digestion, is that they followed absorption for only five hours after digestion.

Apparently the people who did this study didn't in fact know the first thing about digestion.

This makes their result useless, in my opinion, since it already takes about 4-5 hours just for full stomach emptying into the small intestine, where proteins starts to be digested and where you would expect any protein bound phytonutrients to become dissociated and be absorbed. Since they stopped monitoring before a major part of this latter absorption could occur, they are missing all of this action - a major design flaw in the study.

Edited by viveutvivas, 26 September 2012 - 11:32 PM.

[RJ100]

Actually, whey is one of the fasted digested proteins - at most it takes 3 hours for it to be digested, not 5+ hours. The casein will indeed slow things up.

where you would expect any protein bound phytonutrients to become dissociated and be absorbed

I don't think it works that way. In fact, one of the points the papers above make is that once the phenols bind they no longer operate as they did before binding, so being "dissociated" later is irrelevant.

[nowayout]

Actually, whey is one of the fasted digested proteins - at most it takes 3 hours for it to be digested, not 5+ hours. The casein will indeed slow things up.

Digestion of whey does not occur in the stomach, but in the small intestine. Protein is not digested in the stomach. The point is that stomach emptying takes up to 5 hours, so your claim that whey gets fully digested in 3 hours cannot be true if you mean 3 hours after ingestion. If you mean 3 hours after stomach emptying, that is a different story, but then full digestion of whey would occur in up to 8 hours.

where you would expect any protein bound phytonutrients to become dissociated and be absorbed

I don't think it works that way. In fact, one of the points the papers above make is that once the phenols bind they no longer operate as they did before binding, so being "dissociated" later is irrelevant.

How is it irrelevant? Of course, when bound to a protein it makes sense that the phenol will not be bioactive, but once digestion removes the protein, why shouldn't is become bioactive again? Does the paper really describe what happens to a phenol once the protein is removed or are they just talking about the bound state?

Edited by viveutvivas, 27 September 2012 - 03:37 PM.

[RJ100]

Sorry, but you're wrong about milk protein digestion time.

http://www.bodyrecom...estion-pt1.html

It may take that long for the process to complete, but not to begin.

[Kevnzworld]

RJ100:
If you read the first study I posted regarding milk and cocoa polyphenols it states :
" In conclusion, milk powder did NOT influence the average concentration of polyphenols. While it slightly increased absorption , it was of no physiological significance."

The evidence is inconclusive, it think polyphenols have varying molecular weights and chemical compositions which could effect their absorption with different foods. I take my polyphenols with food, because they are food components. I have an open mind however, and your study did cause me to look further into it.
Lastly, I wonder if lactose effected the absorption in the study you posted. Many people have undiagnosed lactose intolerance which effects digestion.

[RJ100]

I agree the evidence is inconclusive.

From wikipedia's entry on casein:

Reviewing previous studies on the impact of milk on absorption of polyphenols, the authors say, "It is a matter of fact that the discrepancy of the results in humans is remarkable, with half the reports suggesting a lack of effect and the other half suggesting an inhibitory effect of milk."

However, for the time being I'm going to stop taking my polyphenols with my protein supplements or any high protein foods like eggs or meat. I don't necessarily want to take them on an empty stomach, though, so maybe with fruit. Hopefully the protein in, say, an apple, would be less likely to interfere, if at all.

[nowayout]

Sorry, but you're wrong about milk protein digestion time.

http://www.bodyrecom...estion-pt1.html

It may take that long for the process to complete, but not to begin.

But that is the whole point - some of the protein obviously reach the small intestine earlier (because stomach emptying occurs bit by bit) but what is relevant is how long it takes digestion to complete. You have to follow digestion up to completion in order to make any kind of statement about how much of a nutrient is absorbed, especially if it is true that phenols stick to casein and and thus may be absorbed slower when taken with milk. It makes no sense to stop following digestion after 5 hours (as they do in the paper) just when the last of the meal enters the small intestine from the stomach. At that point most of the meal is still transiting the small intestine in an incompletely digested state, and will continue to be digested for several hours more. In the paper, they are missing all this action.

By the way, how am I wrong about milk protein digestion? In the graph on that blog you quoted, amino acid levels from casein (a milk protein) are elevated for longer than 7 hours, indicating that milk protein digestion takes at least 7 hours.

Edited by viveutvivas, 27 September 2012 - 08:31 PM.

[kurdishfella]

wait can taking whey protein increase drug absorption if taken together 

 

also what's the best  oral bioavailable drug yall know off besides memantine or tianeptine

Edited by kurdishfella, 06 March 2020 - 03:25 PM.

[kurdishfella]

for me memantine increased the effectiveness off other drugs in high dose