23 replies to this topic

[zoolander]

Heads up peopleIt is proposed that the protein contained in milk somehow reacts with the phenolic compounds which reduces the absorption.

Free Radic Biol Med. 2008 Dec 11.

Antioxidant activity of blueberry fruit is impaired by association with milk.

Antioxidant Research Laboratory, Unit of Human Nutrition, Istituto Nazionale di Ricerca per gli Alimenti e la Nutrizione, 00178 Rome, Italy.

The antioxidant properties of dietary phenolics are believed to be reduced in vivo because of their affinity for proteins. In this study we assessed the bioavailability of phenolics and the in vivo plasma antioxidant capacity after the consumption of blueberries (Vaccinium corymbosum L.) with and without milk. In a crossover design, 11 healthy human volunteers consumed either (a) 200 g of blueberries plus 200 ml water or (b) 200 g of blueberries plus 200 ml of whole milk. Venous samples were collected at baseline and at 1, 2, and 5 h postconsumption. Ingestion of blueberries increased plasma levels of reducing and chain-breaking potential (+6.1%, p<0.001; +11.1%, p<0.05) and enhanced plasma concentrations of caffeic and ferulic acid. When blueberries and milk were ingested there was no increase in plasma antioxidant capacity. There was a reduction in the peak plasma concentrations of caffeic and ferulic acid (-49.7%, p<0.001, and -19.8%, p<0.05, respectively) as well as the overall absorption (AUC) of caffeic acid (p<0.001). The ingestion of blueberries in association with milk, thus, impairs the in vivo antioxidant properties of blueberries and reduces the absorption of caffeic acid.

PMID: 19135520 [PubMed - as supplied by publisher]

Another study using tea by the same author

Eur J Clin Nutr. 1996 Jan;50(1):28-32.

In vivo antioxidant effect of green and black tea in man.
Serafini M, Ghiselli A, Ferro-Luzzi A.

Istituto Nazionale della Nutrizione, Roma Italy.

OBJECTIVE: Evaluation of the vitro antioxidant activity of green and black tea, their in vivo effect on plasma antioxidant potential in man and the effect of milk addition. DESIGN: The antioxidant activity of the tea, with and without milk, was tested in vitro by measuring the length of the peroxyl radical induced lag-phase. The in vivo activity was tested on two groups of five healthy adults. Each group ingested 300 ml of either black or green tea, after overnight fast. The experiment was repeated on a separate day, adding 100 ml whole milk to the tea (ratio 1:4 ). Five subjects acted as controls. The human plasma antioxidant capacity (TRAP) was measured before and 30, 50 and 80 min from the ingestion of tea. RESULTS: Both teas inhibited the in vitro peroxidation in a dose-dependent manner. Green tea was sixfold more potent than black tea. The addition of milk to either tea did not appreciably modify their in vitro antioxidant potential. In vivo, the ingestion of tea produced a significant increase of TRAP (P <0.05), similar in both teas, which peaked at 30-50 min. When tea was consumed with milk, their in vivo activity was totally inhibited. CONCLUSIONS: The paper shows that tea possesses a strong antioxidant activity in vitro which is believed to be exerted by its polyphenols moiety. It also provides compelling evidence that tea has also a potent in vivo activity in man. The promptness of the in vivo response suggests that the absorption of the bioactive components of tea takes place in the upper part of the gastrointestinal system. The inhibition of this effect by milk is thought to be due to the complexation of tea polyphenols by milk proteins. These findings might help to clarify the putative role of dietary poly- phenols in modulating oxidative stress in vivo.

PMID: 8617188 [PubMed - indexed for MEDLINE]

Edited by zoolander, 14 January 2009 - 01:53 AM.

[Shepard]

This is why blueberries should always be consumed in the form of wine.

[mitkat]

This is why blueberries should always be consumed in the form of wine.

Tea, blueberries - what else will milk impair the antioxidant activity of? I'm getting the feeling that sucking on a cow's teet is unnatural from more than a simple moral perspective.

Edited by mitkat, 14 January 2009 - 03:52 AM.
PS. Shep is still a dirty south player

[Shepard]

Tea, blueberries - what else will milk impair the antioxidant activity of?

Chocolate.

[suspire]

Hmm. So would whey protein inhibit the antioxidant activity of blueberries, then? I throw in whey and a bunch of fruit, including blueberries, into my morning shake. Do I need to reformulate?

[Anthony]

Tea, blueberries - what else will milk impair the antioxidant activity of?

Chocolate.

If I recall, it is the lactose in milk which inhibits the chocolate polyphenols; however, I can't find a link (on short notice) which backs that statement up. Anyway, is it also be possible that taking milk in combo with resveratrol will inhibit the formation of resveratrol conjugates (both resveratrol and the nootropic in blueberries are stillbenes)?

If the researchers believe that the proteins inhibit the blueberry polyphenols, then wouldn't it be true that protein from other sources would do the same thing? In other words, if you mix blueberries with any protein type, will you be wasting the berry (so to speak)?

[Shepard]

I know that casein has been blamed for the tea issue. I don't know how lactose would impair the antioxidant effect.

Here is one where milk wasn't quite as nasty against black tea:

Ann Nutr Metab. 2005 May-Jun;49(3):189-95. Epub 2005 Jul 13.Click here to read Links
Addition of milk does not alter the antioxidant activity of black tea.
Reddy VC, Vidya Sagar GV, Sreeramulu D, Venu L, Raghunath M.

Division of Endocrinology and Metabolism, National Institute of Nutrition, Indian Council of Medical Research, Hyderabad, India. challavkr@yahoo.com

Tea is a polyphenol-rich beverage like wine and catechins are its chief polyphenols. Catechins have cardio-protective effects as they can scavenge free radicals and inhibit lipid peroxidation. Epidemiological studies indicate an inverse relation between tea consumption and the risk of cardiovascular and other chronic diseases. Addition of milk to black tea has been reported to adversely affect its beneficial effects, but the data are not unequivocal. Therefore, we assessed the effect of the addition of milk to black tea on its ability to modulate oxidative stress and antioxidant status in adult male human volunteers. Although the area under the curve of plasma catechins was lower on the consumption of tea with milk compared to black tea, it did not affect the beneficial effects of black tea on total plasma antioxidant activity, plasma resistance to oxidation induced ex vivo, and decreased plasma and urinary thiobarbituric acid reactive substance levels. The results suggest that addition of milk may not obviate the ability of black tea to modulate the antioxidant status of subjects and that consumption of black tea with/without milk prevents oxidative damage in vivo. 2005 S. Karger AG, Basel

PMID: 16020939 [PubMed - indexed for MEDLINE]

[Connor MacLeod]

Tea, blueberries - what else will milk impair the antioxidant activity of?

Chocolate.

This one really pains me.

[rwac]

Tea, blueberries - what else will milk impair the antioxidant activity of?

Chocolate.

I wonder if it's possible to make a milkshake which is low lactose & casein free.
Use Heavy cream + Casein free whey as a milk substitute ...
Is all whey casein free ? or does it have very little casein ?

Edited by rwac, 14 January 2009 - 05:23 AM.

[ajnast4r]

Hmm. So would whey protein inhibit the antioxidant activity of blueberries, then? I throw in whey and a bunch of fruit, including blueberries, into my morning shake. Do I need to reformulate?

i believe its the casein portion that is the problem... it decreases the absorption of a lot of phenolic compounds, the ones in green tea & chocolate included.

Is all whey casein free ? or does it have very little casein ?

most good quality isolates should be... ask.

Edited by ajnast4r, 14 January 2009 - 08:13 AM.

[JLL]

What about yoghurt?

[michalhachto]

What about for other proteins, such as in nuts? Is it preferable (for a polyphenol/antioxidant absorption point of view) not to eat blueberries/other berries and nuts (walnuts/almonds/hazelnuts/etc.) at the same time?

[Matt]

For the last few years I've always kept my yogurt intake many hours away from the rest of my diet, so typically I would have a yogurt later in the evening, which is many hours after I stop drinking green tea and having all my fruits/veggies etc..

[Mixter]

I remember the discussion in the resveratrol forum, that milk proteins only inhibited chocolate polyphenols.
Now, maybe it's NOT a good idea to take resveratrol with whey to 'enhance absorption'

[Matt]

I have not seen that whey is the problem here, does anyone have evidence that it is?

[VictorBjoerk]

Blueberries contain a lot of anthocyanins. Anthocyanins are strong inhibitors of inflammation and may reduce autoimmunity in the body.

[Zeb]

I looked around and stumbled upon these. Not sure if there is any merit to them, since I am no expert, but I thought I would throw them out there for your comments. If there are any merit to these studies quoted below perhaps those might help explain the decreased antioxidant activity seen aswell?

Consumption of flavonoid-rich foods and increased plasma antioxidant capacity in humans: cause, consequence, or epiphenomenon?

Lotito SB, Frei B.
Linus Pauling Institute, Oregon State University, 571 Weniger Hall, Corvallis, OR 97331, USA.
Increased fruit and vegetable consumption is associated with a decreased incidence of cardiovascular diseases, cancer, and other chronic diseases. The beneficial health effects of fruits and vegetables have been attributed, in part, to antioxidant flavonoids present in these foods. Large, transient increases in the total antioxidant capacity of plasma have often been observed after the consumption of flavonoid-rich foods by humans. These observations led to the hypothesis that dietary flavonoids play a significant role as antioxidants in vivo, thereby reducing chronic disease risk. This notion, however, has been challenged recently by studies on the bioavailability of flavonoids, which indicate that they reach only very low concentrations in human plasma after the consumption of flavonoid-rich foods. In addition, most flavonoids are extensively metabolized in vivo, which can affect their antioxidant capacity. Furthermore, fruits and vegetables contain many macro- and micronutrients, in addition to flavonoids, that may directly or through their metabolism affect the total antioxidant capacity of plasma. In this article, we critically review the published research in this field with the goal to assess the contribution of dietary flavonoids to the total antioxidant capacity of plasma in humans. We conclude that the large increase in plasma total antioxidant capacity observed after the consumption of flavonoid-rich foods is not caused by the flavonoids themselves, but is likely the consequence of increased uric acid levels.
PMID: 17157175 [PubMed - indexed for MEDLINE]

I found this press release that tells a bit more.

Studies force new view on biology of flavonoids
"If you measure the activity of flavonoids in a test tube, they are indeed strong antioxidants," Frei said. "Based on laboratory tests of their ability to scavenge free radicals, it appears they have 3-5 times more antioxidant capacity than vitamins C or E. But with flavonoids in particular, what goes on in a test tube is not what’s happening in the human body."

Research has now proven that flavonoids are poorly absorbed by the body, usually less than five percent, and most of what does get absorbed into the blood stream is rapidly metabolized in the intestines and liver and excreted from the body. By contrast, vitamin C is absorbed 100 percent by the body up to a certain level. And vitamin C accumulates in cells where it is 1,000 to 3,000 times more active as an antioxidant than flavonoids.

The large increase in total antioxidant capacity of blood observed after the consumption of flavonoid-rich foods is not caused by the flavonoids themselves, Frei said, but most likely is the result of increased uric acid levels.

But just because flavonoids have been found to be ineffectual as antioxidants in the human body does not mean they are without value, Frei said. They appear to strongly influence cell signaling pathways and gene expression, with relevance to both cancer and heart disease.

"We can now follow the activity of flavonoids in the body, and one thing that is clear is that the body sees them as foreign compounds and is trying to get rid of them," Frei said. "But this process of gearing up to get rid of unwanted compounds is inducing so-called Phase II enzymes that also help eliminate mutagens and carcinogens, and therefore may be of value in cancer prevention.

"Flavonoids could also induce mechanisms that help kill cancer cells and inhibit tumor invasion," Frei added.

It also appears that flavonoids increase the activation of existing nitric oxide synthase, which has the effect of keeping blood vessels healthy and relaxed, preventing inflammation, and lowering blood pressure – all key goals in prevention of heart disease.

And this study says that milk decreases the serum uric acid levels..

Milk- and soy-protein ingestion: acute effect on serum uric acid concentration.

Garrel DR, Verdy M, PetitClerc C, Martin C, Brulé D, Hamet P.
Hotel-Dieu de Montreal, Quebec, Canada.
Acute effect of the ingestion of 80 g each of casein, lactalbumin, and soybean isolate on serum and urinary uric acid concentrations was investigated in 10 healthy subjects. Serum and urinary uric acid concentrations were measured before and after the ingestion of proteins. Serum uric acid decreased significantly 3 h after ingestion of lactalbumin and casein but increased after soybean consumption. Urate clearance was significantly increased after ingestion of each of the three proteins. Multivariate analysis of urate clearance during lactalbumin and casein loads showed that independent correlation was obtained for serum alanine and urea concentration. These results demonstrate that, in addition to their known uricosuric effect, milk proteins acutely decrease serum uric acid concentration. Analysis of the effects of lactalbumin and casein on urinary uric acid elimination suggests that the uricosuric effect of proteins is a multifactorial phenomenon.
PMID: 2000819 [PubMed - indexed for MEDLINE]

[JLL]

"We can now follow the activity of flavonoids in the body, and one thing that is clear is that the body sees them as foreign compounds and is trying to get rid of them," Frei said. "But this process of gearing up to get rid of unwanted compounds is inducing so-called Phase II enzymes that also help eliminate mutagens and carcinogens, and therefore may be of value in cancer prevention."

^ Does this mean that increasing the rate of flavonoid absorption is a bad idea? For example, it seems that black pepper (or piperine) increases the bioavailability of EGCg in green tea. But if it's not the absorption but the getting rid of them that is behind the positive effects, should we stay away from things like piperine?

[stephen_b]

Is all whey casein free ? or does it have very little casein ?

Whey is what is left after you remove the casein.

[FunkOdyssey]

Are we pretty certain now that casein is the responsible milk component for the interference with blueberry polyphenols? I've been eating my oatmeal with a cup of blueberries and 30g of ion-exchange whey protein isolate every day, and I'll be upset/disappointed/embarassed if the whey is problematic.

[JLL]

I'm still not entirely sure milk really inhibits the antioxidant activity of tea. There seems to be conflicting data. I wrote about one study that suggested green tea and black tea increase plasma antioxidant activity even when milk is added. It did reduce the activity of black tea with time (after 2 hours), but since the peak occurs 20-40 minutes after drinking, it doesn't seem so bad. I'll have to read the whole paper of the study Zoolander posted to get a better view of why these results don't seem to match.

[nowayout]

Are we pretty certain now that casein is the responsible milk component for the interference with blueberry polyphenols? I've been eating my oatmeal with a cup of blueberries and 30g of ion-exchange whey protein isolate every day, and I'll be upset/disappointed/embarassed if the whey is problematic.

I would be in even worse shape, since I have most of my berries together with yoghurt on oatmeal. Never mind the casein, I'm wondering if the oatmeal fiber doesn't also bind and inhibit absorption of phytonutrients from the berries. On the other hand, unless one is otherwise malnourished, how much good is this kind of worry really likely to do one? It seems unlikely (but it would be ironic if true ) that not separating one's berries from one's milk products would subtract years off one's life, like some divine retribution for not keeping kosher . As for myself, further feeding my health-related obsessive tendencies would be more likely to kill me first anyway.

Edited by andre, 02 March 2009 - 06:23 PM.

[FunkOdyssey]

I spent about five minutes worrying about and typing my post about the issue. If the effort produces another hour of lifespan it will have been one of the wiser investments of time I made today.

[nowayout]

I spent about five minutes worrying about and typing my post about the issue. If the effort produces another hour of lifespan it will have been one of the wiser investments of time I made today.

For me it is not about the five minutes, though. It is about the sheer exhaustion and inconvenience of incorporating avoidance of various food combinations, dosing schedules, etc., into the rest of one's life. How worthwhile is buying extra time at the cost of having to follow a rigid and regimented lifestyle? I guess the answer depends on how much extra time and health we are talking about and one's own and one's loved ones' tolerance for regimentation. Anyway, sorry for kind of holding up this thread with my musings - I am as curious as anyone to see more evidence either way on the issue.