A study from the Linus Pauling Institute showed that
eating large amounts of apples did not result in that antioxidant benefits
of apple polyphenol extracts.
In one human study,
apple polyphenolsincreased the
activity of SOD (superoxide dismutase), one of your body's most important and
powerful natural antioxidants, by 41%.
An unpublished paper from Japan, available
exclusively to our readers, points out that
polyphenols from apples are
among the few known
water-soluble plant polyphenols.
Polyphenols may not be absorbed at all in the presence
of sugar molecules, say researchers in the Netherlands, strengthening the
case for apple polyphenol extracts.
Relevance of apple polyphenols as antioxidants in
human plasma: contrasting in vitro and in vivo effects.
Lotito SB, Frei B.
Linus Pauling Institute, Oregon State University, Corvallis, OR 97331, USA.
Apples are a major source of flavonoids in the Western diet, and flavonoid-rich
foods may help protect against chronic diseases by antioxidant mechanisms.
In the present study we investigated: (1) the antioxidant capacity of
representative apple polyphenols and their contribution to the total
antioxidant capacity of
apple extracts;
(2) the effects of adding apple
extract to human plasma in vitro on oxidation of endogenous
antioxidants and lipids; and (3) the effects of apple consumption by humans
on ex vivo oxidation of plasma antioxidants and lipids. We found that the
apple-contained flavonols and flavanols, quercetin, rutin, (-)-epicatechin,
and (+)-catechin, had a higher antioxidant capacity than the
dihydrochalcones, phloridzin and phloretin, and the hydroxycinnamate,
chlorogenic acid. However, together these apple polyphenols contributed less
than 20% to the total antioxidant capacity of aqueous
apple extracts.
When human plasma was exposed to a constant flux of aqueous peroxyl
radicals, endogenous ascorbate (70.0 +/- 10.3 microM) was oxidized within 45
min of incubation, while endogenous urate (375 +/- 40 microM) and alpha-tocopherol
(24.7 +/- 1.2 microM) were oxidized after ascorbate. Addition of 7.1 or 14.3
micrograms/ml total phenols of
apple extract
did not protect ascorbate from oxidation, but increased the half-life (t1/2)
of urate from 136 +/- 15 to 192 +/- 16 and 208 +/- 23 min, respectively (p <
0.05 each), and t1/2 of alpha-tocopherol from 141 +/- 18 to 164 +/- 8 min (p
= ns) and 188 +/- 8 min (p < 0.05). Lipid peroxidation started after
ascorbate depletion, and addition of apple extract increased the lag time preceding detectable
lipid peroxidation from 36.3 +/- 3.7 to 50.9 +/- 2.7 min (p < 0.05) and 70.4
+/- 4.2 min (p < 0.001). However, when
six healthy volunteers ate five
apples and plasma was obtained up to 4 h after apple consumption, no
significant increases in the resistance to oxidation of endogenous urate,
alpha-tocopherol, and lipids were found. Thus, despite the high antioxidant
capacity of individual apple polyphenols and apple extracts and the
significant antioxidant effects of apple extract added to human plasma in
vitro, ingestion of large amounts of
apples by humans does not appear to result in equivalent in vivo antioxidant
effects of
apple polyphenols.
PMID: 14744632 [PubMed - indexed for MEDLINE]
Journal of
the American College of Nutrition, Vol. 22, No. 3, 217-223 (2003)
Effects of Phenol-Depleted and Phenol-Rich Diets on Blood Markers of
Oxidative Stress, and Urinary Excretion of Quercetin and Kaempferol in
Healthy Volunteers
Hwa-Young Kim,
MSc, Ok-Hee Kim, PhD and Mi-Kyung Sung, PhD
Department of Food and
Nutrition, Sookmyung Women’s University (H.-Y.K., M.-K.S.), Seoul, KOREA
National Institute of Toxicological Research, Korea Food and Drug
Administration (O.-H.K.), Seoul, KOREA
Address reprint requests
to: Mi-Kyung Sung, Ph.D., Associate Professor, Department of Food and
Nutrition, Sookmyung Women’s University, 53-12 Chungpa-dong 2-ka, Yongsan-ku
Seoul, 140-742, KOREA. Email: mksung@sookmyung.ac.kr
Objective:
Epidemiological studies have suggested beneficialeffects of
dietary polyphenols
in reducing the risk of chronicdiseases. This study was
performed to investigate the effectsof polyphenol-depleted and
polyphenol-rich diets on blood oxidativestress markers and
urinary excretions of major phenols.
Methods: Nineteen healthy
female non-smokers 19 to 21 yearsof age took part in the study,
which consisted of two dietaryintervention periods separated by
three days. Experimental dietswere composed of common foods
selected to comply with low contentsof
polyphenols
for phenol-depleted intervention and high contentsof
polyphenols
for phenol-rich diets. Blood and urine sampleswere collected on
day 0, 3 and 6 of each intervention. Duplicateportions of foods
provided to the subjects were also collected.Blood oxidative
stress markers included plasma antioxidant vitamins,erythrocyte
superoxide dismutase (SOD) activity and lymphocyteDNA damage.
Urinary excretions of major phenols
were measuredto affirm bioavailability of dietary phenols.
Results:
Plasma -tocopherol
and ß-carotene concentrationswere slightly decreased on day 3
and 6 of the phenol-depleteddietary intervention period,
although no change was observedwith phenol-rich diets. The
erythrocyte SOD activity was alsoslightly decreased during
phenol-depleted dietary intervention.However,
at day 6 of the phenol-rich
intervention, the activityof SOD was significantly increased by
41%. Tail moment and taillength of lymphocyte DNA as
markers of DNA damage were higheron day 6 of phenol-depleted
intervention, although only tailmoment showed a statistical
significance. The average intakesof quercetin and kaempferol
during the phenol-rich interventionwere 21 mg/day and 9 mg/day,
respectively. The average urinaryexcretion rates during
phenol-rich intervention were 2.06% forquercetin and 0.46% for kaempferol. There were positive
correlationsbetween erythrocyte SOD activity and urinary
concentration ofquercetin or kaempferol.
Conclusions:
These results suggest that polyphenol-rich dietsmay decrease the
risk of chronic diseases by reducing oxidativestress.
J Nutr.
2004 May;134(5):1105-9.
Cold-storage
affects antioxidant properties of apples in Caco-2 cells.
Tarozzi A, Marchesi A, Cantelli-Forti G, Hrelia P.
Department of Pharmacology, University of Bologna, 40126 Bologna, Italy.
Data on the composition of phenolic antioxidant compounds present in food
plants and assessment of their activity are essential for epidemiological
explanation of the health benefits of fruit and vegetables. Various factors
such as cultivation methods, industrial processing, and
storage may affect
the final concentrations of phytochemicals in food plants and their
eventual
bioactivity. This study investigated the influence of commercial
cold-storage periods on the antioxidant properties of
apples grown either by
organic or integrated systems. In both cases,
total phenolics and total
antioxidant activity decreased only in the first 3 mo and only in apples
with skin (P < 0.05), suggesting that
cold storage rapidly impoverishes
these properties in skin but not in pulp. Assessment of antioxidant
bioactivity in vitro, measured in terms of intracellular antioxidant, cytoprotective, and antiproliferative activity in human colon carcinoma
(Caco-2) cells (differentiated to normal intestinal epithelia for
intracellular antioxidant and cytoprotective effects), showed
strong,
time-related decreases over 6 mo of cold storage for all 3 parameters (P <
0.01), irrespective of the cultivation system. These findings with
integrated and organic apples further support the concept that organic
systems of cultivation do not generally provide real health benefits.
Moreover, the data from the present study
clearly show that factors such as
cold storage may affect the antioxidant properties of apples.
Epidemiological studies on the cancer-preventive benefits of fruits and
vegetables should take into account the cold-storage bias for apples, and
possibly for other products.
PMID: 15113953 [PubMed - indexed for MEDLINE]
Anal Biochem. 2001 Oct
15;297(2):144-53
High-throughput
fluorescence screening of antioxidative capacity in human serum.
Mayer B, Schumacher M, Brandstatter H, Wagner FS,
Hermetter A.
Department of Biochemistry, Technische Universitat Graz, Graz, A-8010,
Austria.
Diphenylhexatriene-labeled phosphatidylcholine and propionic acid have been
established as selective fluorescence markers for the continuous
determination of oxidation processes in the lipid and aqueous phases of
unfractionated human serum. Oxidation of the respective fluorophores leads
to a decrease in fluorescence intensity from which the time-dependent
degradation of the marker molecule can be determined. The lag times
preceding the propagation of oxidation are representative for the
antioxidative capacity of the system, which may be influenced by exogenous
factors, e.g., the antioxidants from the diet.
Supplementation of human serum by
quercetin, rutin, vitamin E, vitamin C,
or total applephenolics in vitro
led to a decrease in oxidizability depending on the oxidation marker
and the hydrophobicity of the antioxidant. Quercetin and vitamin E showed a
higher in vitro capacity of protecting lipoproteins against oxidation. In
contrast, rutin and vitamin C were more efficient as inhibitors in the
aqueous phase. The same effect on
serum was found after dietary consumption of apples. This result is in line
with the known observation that intake of plant polyphenols leads to an
increase in serum levels of hydrophilic antioxidants. Copyright 2001
Academic Press.
Publication Types:
·
Clinical Trial
PMID: 11673881 [PubMed - indexed for MEDLINE]
J Agric Food
Chem. 2003 Sep 10;51(19):5780-5.
Apple and pear
peel and pulp and their influence on plasma lipids and antioxidant
potentials in rats fed cholesterol-containing diets.
Leontowicz M, Gorinstein S, Leontowicz H, Krzeminski R,
Lojek A, Katrich E, Ciz M, Martin-Belloso O, Soliva-Fortuny R, Haruenkit R,
Trakhtenberg S.
Department of Animal Physiology, Faculty of Veterinary Medicine, Warsaw
Agricultural University, Nowoursynowska 166, 02-787 Warsaw, Poland.
The aim of this study was to assess
the bioactive compounds of apple and pear peel and pulp in vitro
and their influence on plasma lipids
and antioxidant potentials in vivo. The antioxidant potentials
measured by 1,1-diphenyl-2-picrylhydrazyl (DPPH), beta-carotene bleaching
(beta-carotene), and nitric oxide inhibition radical scavenging (NO)
tests inapple peel and pulp were
significantly higher than in pear peel and pulp, respectively. The
ethanol extract of apple peels showed the strongest inhibition of lipid peroxidation as a function of its concentration and was comparable to the
antioxidant activity of butylated hydroxyanisole. The pear pulp extract had
the weakest antioxidant ability, whereas other extracts such as apple pulp
and pear peel were nearly equal. The antioxidant activities comprised
contributions from polyphenols,
phenolic acids, and flavonoids and
correlated well with polyphenols and flavonoids. The correlation
coefficients between polyphenols and antioxidant activities by DPPH,
beta-carotene, and NO were as follows: 0.9207, 0.9350, and 0.9453.
Contrarily, the correlation coefficient between the content of dietary fiber
and the antioxidant activities test was low. The content of all studied
indices in apple and pear peel was significantly higher than in peeled
fruits (p < 0.05). Diets
supplemented with fruit peels exercised a significantly higher positive
influence on plasma lipid levels and on plasma antioxidant capacity of rats
than diets with fruit pulps.
PMID: 12952433 [PubMed - indexed for MEDLINE]
J Nutr Biochem.
2002 Oct;13(10):603-610.
Comparative
content of some bioactive compounds in apples, peaches and pears and their
influence on lipids and antioxidant capacity in rats.
Leontowicz H, Gorinstein S, Lojek A, Leontowicz M, Ci;z M, Soliva-Fortuny
R, Park YS, Jung ST, Trakhtenberg S, Martin-Belloso O.
Department of Physiology, Biochemistry, Pharmacology and
Toxicology, Faculty of Veterinary Medicine, WarsawAgriculturalUniversity,
Nowoursynowska 166, 02-787, Warsaw, Poland
The aim of this study was to compare some
bioactive compounds in apples,
peaches and pears and their influence on lipids and antioxidant capacity in
rats. The content of total polyphenols (g/100g) was 0.23 +/- 0.03; 0.22 +/-
0.03 and 0.68 +/- 0.1 in peeled fruits and 0.48 +/- 0.04, 0.47 +/- 0.04 and
1.2 +/- 0.12 in peels of peaches, pears and apples, respectively. Caffeic,
p-coumaric and ferulic acids and the
total radical-trapping antioxidative potential (TRAP) values in peeled
apples and their peels were significantly higher than in peaches and
pears, respectively. Contrarary, no significant differences in the content
of dietary fiber among the studied fruits were found. The content of all
studied indices in peels was significantly higher than peeled fruits (p <
0.05 ). A good correlation between the total
polyphenols and the TRAP values
was found in all fruits. Diets
supplemented with apples and to a less extent with peaches and pears
have improved lipid metabolism and
increased the plasma antioxidant potential especially in rats fed with added
cholesterol. The highest content of biologically active compounds and the
best results in the experiment on rats makes apple preferable for dietary
prevention of atherosclerosis and other diseases.
PMID: 12550072 [PubMed - as supplied by publisher]
Nikka Whiskey Distilling
Company, Ltd., Chiba Japan
Antioxidant Component and Biological
Regulatory Functions in Apple Polyphenols
Akio Yanagida, Institute for Product Research and
Development, Nikka Whiskey Distilling Company, Ltd., Chiba Prefecture, Japan
(Mr. Yanagida is a principal member of product research
and development for this Japanese company, a leader in the development of
extraction, purification, and commercial applications of
apple
polyphenol extracts
in Japan. We have obtained this unpublished paper through private channels.)
Excerpts: "Apples
contain high concentrations of polyphenol compounds that have high water
solubility."
"Another characteristic of applecondensed tannins (ACT, catechin polymers) is significantly
higher water solubility compared to catechin monomers. In general,
many plant polyphenols are water-insoluble, and
polyphenols with easy solubility in
pure water are quite rare. Thus, this ACT characteristic is
especially noteworthy."
Biomed
Pharmacother. 1997;51(8):305-10.
Absorption, metabolism and health effects of dietary
flavonoids in man.
Hollman PC, Katan MB.
DLO State Institute for Quality Control of Agricultural Products (RIKILT-DLO),
Wageningen, The Netherlands.
Flavonoids are
polyphenolic
compounds that occur ubiquitously in foods of plant origin. Over
4,000 different flavonoids have been described, and they are categorized
into flavonols, flavones, catechins, flavanones, anthocyanidins and
isoflavonoids. Flavonoids have a variety of biological effects in numerous
mammalian cell systems, in vitro as well in vivo. Recently, much attention
has been paid to their antioxidant properties and to their inhibitory role
in various stages of tumour development in animal studies. Quercetin, the
major representative of the flavonol subclass, is a strong antioxidant, and
prevents oxidation of low density lipoproteins in vitro. Oxidized low
density lipoproteins are atherogenic, and are considered to be a crucial
intermediate in the formation of atherosclerotic plaques. This agrees with
observations in epidemiological studies that the intake of flavonols and
flavones was inversely associated with subsequent coronary heart disease.
However, no effects of flavonols on cancer were found in these studies. The
extent of absorption of flavonoids is an important unsolved problem in
judging their many alleged health effects.
Flavonoids present in foods were
considered non-absorbable because they are bound to sugars as
beta-glycosides. Only free flavonoids without a sugar molecule, the
so-called aglycones, were thought to be able to pass through the gut wall.
Hydrolysis only occurs in the colon by microorganisms, which at the same
time degrade flavonoids. We performed a study to quantify absorption of
various dietary forms of quercetin. To our surprise, the quercetin
glycosides from onions were absorbed far better than the pure aglycone.
Subsequent pharmacokinetic studies with dietary quercetin glycosides showed
marked differences in absorption rate and bioavailability. Absorbed
quercetin was eliminated only slowly from the blood. The metabolism of
flavonoids has been studied frequently in various animals, but very few data
in humans are available. Two major sites of flavonoid metabolism are the
liver and the colonic flora. There is evidence for O-methylation, sulphation
and glucuronidation of hydroxyl groups in the liver. Bacterial ring fission
of flavonoids occurs in the colon. The subsequent degradation products,
phenolic acids, can be absorbed and are found in urine of animals.
Quantitative data on metabolism are scarce.
