Physiological properties of beetroot crisps applied in standard and dyslipidaemic diets of rats
Monika Wroblewska
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Jerzy Juskiewicz
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Wieslaw Wiczkowski
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Institute of Animal Reproduction and Food Research of the Polish Academy of Sciences in Olsztyn
,
Poland
Background: The objective of the present study was to examine the influence of adding various amounts beetroot (Beta vulgaris) crisps on gastrointestinal function, antioxidant status and blood and liver lipid profiles in a high fat diet-induced dyslipidaemic rat model; Results: The intake of a dyslipidaemic diet increased the serum total cholesterol, total cholesterol-to-HDLcholesterol ratio, atherogenic index, hepatic total cholesterol and triacylglycerols, suppressed production of shortchain fatty acids and decreased total antioxidant status and blood glutathione peroxidase activity. Oral administration of all tested amounts of beetroot crisps prevented the rise in serum total cholesterol and triacylglycerols levels. The treatment with the addition of 3% crisps also decreased hepatic total cholesterol level and activity of AST in serum. The experimental addition of crisps likewise resulted in a tendency towards a higher total SCFA pool and activity of glutathione peroxidase and a lower serum glucose level (p = 0.080, p = 0.061 and p = 0.067, respectively); Conclusions: Results of the presented study suggest that the addition of beetroot crisps could alleviate metabolic changes in dyslipidaemic diet-administered rats.
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Background
A Western diet heavy in meat, fried foods and refined
grains increases the risk of developing metabolic
syndrome, heart problems, stroke and type 2 diabetes. The
link between diet and chronic disease is well
documented. Heart disease, the main cause of death in Western
countries, is greatly influenced by diet, especially by the
amount and type of fat consumed. Nutritionists
recommend diets rich in fruits and vegetables for good health
and for reducing the risk of heart disease and some
types of cancers. The beneficial effects of fruits,
vegetables and a Mediterranean diet are likely due to many
components, including fibre and micronutrients [1]. The
fundamental active agents for reducing the risk of
chronic diseases are antioxidants [2]. Over the last
several years, increasing attention has been paid to the
antioxidant activity of plant pigments such as
caretonoids, anthocyanins and, recently, the betalains [3,4].
The most heavily studied betalain is betanin aglycone,
obtained from the extract of beet juice. Beetroot is
mainly consumed as a pickled or canned preserve, a
cooked vegetable or sometimes a juice. In Poland, red
beets are popular vegetables with a per capita
consumption of approximately 6 kg/year. Results from several in
vitro studies have demonstrated that betalains from
beetroots possess powerful antiradical and antioxidant
activity [5-8]. In addition, a significant tumour inhibitory
effect has been shown to accompany a dietary treatment
with beetroot ingestion [9]. Lammers [10] hypothesized
that betanin is non-perturbing to cellular metabolism,
highly compatible with enzyme function and steadies
cellular metabolic function under various kinds of stress
in animal tissue. Introduction of novel products, mainly
lacto-fermented juice and crisps, has presumably
contributed to the recent growth in the intake of beetroot.
Some epidemiological studies have shown a contrary
correlation between fruit/vegetable intake and the risk
of cardiovascular disease, especially when the blood lipid
profile is considered [11,12].
In this study, the hypothesis that the consumption of a
diet containing beetroot crisps could beneficially affect
gastrointestinal function, antioxidant status of the body,
and blood and liver lipid profiles was verified. To test
this hypothesis, different amounts of beetroot crisps
were applied to a Western-type and a dyslipidaemic diet.
Materials and methods
Beetroot crisps were obtained from Paula Co. (Kalisz,
Poland) and contained 14.6 g of crude protein, 48.4 g of
carbohydrates and 0.4 g fat per 100 g of crisps.
The extraction, quantification and identification of
betalains from beetroot crisps is described below. About
0.10 g of pulverized red beet crisps was extracted with 1
ml of distilled water by with triplicate 60-s sonication
and 60-s vortexing. After centrifugation (13200 g at 4
C, 5 min), the supernatant was collected in a 5-ml flask.
These steps were repeated 5 times. Quantification of
betalains was determined by a spectrophotometric
method according to the modified method of Stintzing
[13]. Briefly, before analysis aliquots of red beet crisps
extract was centrifuged (8400 g, 5 min). Next, the
sample was dissolved in McIlvaine buffer (pH 6.5) to
obtain an absorbance (A) of 0.8 A 1.0. The
betacyanins and betaxanthins contents were calculated as
betanin-equivalents and vulgaxanthin-equivalents,
respectively, using the following formula: [mg/g dry
matter] = (A*R*MW*V*1000)/*W, where A is the
absorption at 538 nm and 480 nm for betacyanins and
betaxanthins, respectively, R i (...truncated)