Current Nutrition & Food Science - Volume 3, Issue 4, 2007

Nutrition plays an important role in various diseases. It is known that consumption of energy dense diet, lack of exercise, and other life style factors lead to obesity and its associated conditions such as type 2 diabetes mellitus, dyslipidemia, hypertension, and coronary heart disease. There is reasonable evidence to support the contention that certain types of cancers are more common in subjects with obesity. With an increase in affluence and changes in life style factors, and adoption of Western dietary habits seem to have accelerated the increase in the incidence of metabolic syndrome X even in developing countries such as India, China and other Asian nations. Thus, obesity, and its associated diseases including metabolic syndrome X are assuming epidemic proportions in both developed and developing nations. Hence, urgent measures are needed to arrest the progress of this epidemic. In view of this, the present special issue of Current Nutrition and Food Science is devoted to the relationship between dietary factors and various diseases. The topics covered include: metabolic syndrome X, cancer, antioxidant properties of green tea extract, antibiotic-like actions of Propolis, chemoprotective effects of conjugated linolenic acids obtained from plant seed oils, vitamin E and bone quality, relationship between Mediterranean diet and metabolic syndrome X, clinical significance of various lipid mediators, and bioinformatics approach to insulin resistance syndrome. The contributors to this special issue have come from varied backgrounds and this ensured that a broad range of topics is covered. I trust that readers enjoy this special issue. It will be my pleasure to hear the opinion of the readers about the topics covered.

Using bioinformatics techniques and sequence analyses algorithms, we identified that tumor necrosis factor-α (TNF-α) and nitric oxide (NO) have a significant role in the pathobiology of insulin resistance syndrome, a condition that is common in subjects with abdominal obesity, hypertension, dyslipidemia, atherosclerosis, and coronary heart disease and are accompanied by endothelial dysfunction due to reduced endothelial nitric oxide generation. TNF-α has neurotoxic actions, stimulates inducible NO synthase activity, and modulates the expression of neurotransmitters involved in the control of feeding and thermogenesis. NO is a neurotransmitter and influences secretion and actions of various hypothalamic peptides and neuropeptides. Insulin suppresses the production of TNF-α but stimulates that of endothelial NO. This close interaction between TNF-α, NO, hypothalamic peptides, and insulin suggests that regulation of TNF-α and NO production and action could be critical in the management of insulin resistance syndrome and its associated conditions.

Lipid mediators are a heterogenous group of bioactive lipids which includes eicosanoids, resolvins, endocannabinoids, sphingolipids, phospholipids and oxidized lipids. They mediate several physiological cellular functions but also participate in the pathogenesis of many diseases such as diabetes, cardiovascular diseases, autoimmune diseases and cancer. Many food-derived bioactive compounds can beneficially alter their metabolism or actions offering an attractive adjunct to the existing conventional therapies of the above diseases. Omega-3 fatty acids, polyphenols, phytosterols, vitamins and organosulfur compounds are potent modulators of lipid mediators' biochemistry in vitro while an increased intake of foods, rich in the aforementioned ingredients, is related with a favorable clinical profile of many pathological conditions. Platelet activating factor (PAF) is one of the most potent inflammatory lipid mediators playing a crucial role in the initiation and propagation of atherosclerosis, therefore, the presence of PAF inhibitors in various foodstuffs is very important in terms of their nutritional value. Several dietary macronutrients and microconstituents, of plant origin mainly, are able to antagonize PAF actions and attenuate its effect in vivo. This article summarizes the effects of food ingredients on the metabolism and actions of lipid mediators. Special attention is given to the dietary modulation of PAF.

Metabolic syndrome X is an inflammatory condition. Increased consumption of high-energy diet, saturated and trans-fats by pregnant women and lactating mothers suppresses the activities of enzymes Δ6 and Δ5 desaturases in maternal and fetal tissues resulting in a decrease in the concentrations of long-chain polyunsaturated fatty acids (LCPUFAs) such as arachidonic acid (AA), eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA). These LCPUFAs have a regulatory role on inflammation. EPA, DHA, and AA augment eNO synthesis, augment insulin action both in the peripheral tissues and brain, and are critical for brain growth and development, synaptogenesis, and modulate the action of neurotransmitters and hypothalamic peptides. These evidences suggest that sub-optimal LCPUFAs during perinatal period could initiate low-grade systemic inflammation and development of metabolic syndrome X in these children if they continue to consume energy dense diet. This implies that perinatal supplementation of LCPUFAs could aid to prevent, arrest or postpone the development of metabolic syndrome X.

The metabolic syndrome is a clustering of metabolic abnormalities and cardiovascular risk factors (like visceral obesity, dyslipidemia, hypertension and hyperglycemia) that occur in individuals with impaired insulin resistance and subclinical inflammation. During the past years this syndrome has become one of the major public health threats worldwide. Growing evidence demonstrates that dietary patterns, such as Mediterranean diet, rich in fruits and vegetables, legumes, cereals and moderate intake of meat and its products, are beneficial to health, and, particularly, to many metabolic disorders. The aim of the present review is to focus on the current evidence that exist on the relationship between Mediterranean diet and metabolic syndrome's components, based on epidemiological and clinical findings.

Vitamin E is known to improve antioxidant status, but the effect of vitamin E on bone quality in orchidectomized rats is unknown. In the present study, thirty-two 1-y-old male rats were randomized to two groups: a sham-control group (n=8) and an orchidectomized group (n=24). The orchidectomized group was divided into three groups of eight and assigned to one of the following treatments: orchidectomy (ORX), low-dose vitamin E of 65.6 mg/Kg diet or high-dose vitamin E of 656 mg/Kg diet. Four months after the study began, all rats were killed, blood was collected, and plasma was harvested for antioxidant status, tartrate resistant acid phosphatase (TRAP), and IGF-I. Orchidectomy decreased (P<0.05) plasma antioxidant and IGF-I, reduced bone (P<0.05) quality and bone strength, increased (P<0.05) plasma TRAP and urinary excretion of calcium and magnesium compared to the sham-control group. In contrast to ORX, vitamin E increased (P<0.05) plasma antioxidant and had no beneficial effect on indices of bone quality, bone resorption and bone formation marker, or urinary calcium and magnesium excretion. In conclusion, vitamin E appears to decrease oxidative stress without improving bone quality in orchidectomized rats.

Propolis is a natural substance collected by bees from local flora. Propolis is increasingly used in health-food manufacturing practices since in addition to the antibacterial, antifungal, and antiviral characteristics, it also strengthens the immunity and has a strong antioxidative effect. We investigated the chemical composition and antimicrobial activity of 10 samples of propolis, which were collected in different regions of Lithuania. The highest concentrations of phenolic compounds, the main active substances of propolis, were found in the samples which were collected from the hives located in the proximity of forests of a mixed type. The highest amounts of flavonoids were detected in propolis samples that were obtained from the bee hives located in the meadows All samples of propolis ethanolic extract were active against gram-positive, gram-negative bacteria and fungi. The antimicrobial activity was higher against gram-positive than against gram-negative bacteria. One propolis sample showed relatively strong activity against Candida albicans - minimum inhibitory concentration (MIC) - 0.009 g/100ml of phenolic compounds. The antimicrobial activity of propolis may be due to the synergistic effect of phenolic compounds, terpenoids, aromatic and aliphatic acids.

Conjugated fatty acids (CFA) being novel type of biologically functional lipid substances, have received increased interest owing to their beneficial effects on human health. Among CFAs, conjugated linoleic acids (CLA) have been reviewed extensively for their occurrence, health benefits, industrial production and applications. On the contrary, it is worth noting that some plant seeds contain conjugated linolenic acids (CLN) at considerably higher levels (30 to 70 wt% lipid), although other kinds of CFAs including CLA are only found at concentrations less than 1% in natural products. It is thus imperative that CLN are the only CFAs that occur in higher quantities in nature and we have extensively screened CLN from different plant seed oils for their chemopreventive effects. In the ensuing review, we describe in detail the physiological functions of CLN isomers that occur in some plant seeds. CLN from natural origin showed growth inhibitory and apoptotic effects on cancer cells and the activity was dependent on their geometrical/positional structures. All trans CLN exerted stronger growth inhibition and more DNA fragmentation in human colon cancer cells than corresponding CLN isomer with cis configuration. CLN induced apoptosis through decrease of Bcl-2 protein. It will be interacted with increase in PPARγ signaling and up-regulation of gene expression of GADD45 and p53. Enhancement of PPARγ expression was also observed in the rats fed seed oil rich in CLN. Dietary feeding of these CLN-containing seed oil reduced the frequency of colonic aberrant crypt foci (ACF) in rat that is the precursor of colon carcinogenesis in short-term experiment and inhibited the development of colonic adenocarcinoma in long-term experiment.

An experiment was conducted to evaluate the effect of feeding orange pulp on plasma antioxidant status and bone quality in orchidectomized rats. Forty-five one-year-old male rats were randomly placed in a sham-control group and four orchidectomized groups. Orchidectomized rats were assigned to one of the following treatments: orchidectomy (ORX), ORX+2.5% orange pulp (OP); ORX+5.0% OP; ORX+10.0% OP. Four months after the study began, all rats were killed, blood was collected, and the plasma was harvested for antioxidant status and IGF-I. Orchidectomy did not (P>0.1) affect red blood cell hemolysis percentage, but decreased (P<0.05) the plasma IGF-I concentration, bone density, femoral strength, time induced femoral fracture, calcium and magnesium concentrations in the femur and the 5th lumbar, and increased (P<0.05) urinary deoxypyridinoline, calcium and magnesium excretions compared to the sham group. Feeding 2.5% OP tended to increase IGF-I and increased (P<0.05) bone density, femoral strength, and time induced femoral fracture. Feeding 10% OP profoundly (P<0.05) improved antioxidant status by protecting red blood cells against hemolysis, increased (P<0.05) the plasma IGF-I, bone density and bone mineral content, and decreased (P<0.05) urinary magnesium excretion and urinary deoxypyridinoline concentration. In conclusion, orange pulp significantly affects bone quality by enhancing calcium and magnesium deposition in bones and by slowing-down bone turnover rate.

Green tea preparations are currently widely used in Lithuania, and therefore capsules with dry green tea extract were chosen with the aim of determination of their polyphenol and caffeine contents and antioxidant activity, as well as for the evaluation of the correlation between possible indicators. The amount of polyphenolic compounds was determined using the Foulin - Ciocalteau reagent, standard galic acid, and following spectrophotometry. Qualitative and quantitative determination of the caffeine was performed using high performance liquid chromatography. Antioxidant activity was determined by applying the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical binding method and inhibition of tyrosine nitration technique. The study showed that the amount of polyphenols and caffeine in the extract depends not only on the quality of the vegetal stock, but also on the technological parameters of processes applied in the production of dry extract. Antioxidant activity directly correlated with the amount of polyphenols in the extract. The quality of the green tea extract capsules was evaluated and, the allowable amounts of polyphenols (not less than 150 mg) and caffeine (not less than 16 mg) per capsule were established.