Kirtan V. Tarwadi

Vitamin profile of cooked foods: how healthy is the practice of ready-to-eat foods?

During recent years importance of B complex vitamins, beta-carotene and vitamin C has been realised in terms of their antioxidative and anticarcinogenic properties. Fruits and vegetables are the rich sources of these vitamins. However, there are considerable cooking losses of vitamins, and information on vitamin contents of cooked foods is essential for assessing the adequacy of vitamin intakes. Secondly, there is a growing trend to consume ready-to-eat foods such as stuffed pancakes (samosa, patties), pastries, French fries; replacing traditional foods for lunch or dinner like roti, vegetable curry, bread, non-vegetarian items. Ready-to-eat foods are considered to give empty calories rather than a balanced diet. A study was undertaken to estimate ascorbic acid, folic acid, riboflavin, thiamine and betacarotene of 263 cooked food samples and 260 meals representing dietary patterns of Asia, Africa, Europe, USA and Latin America by spectrophotometry and photoflurometry. A broad range of beta-carotene (84-2038 mcg%), riboflavin (0.01-0.48 mg%), thiamine (0.04-0.36 mg%), vitamin C (1-28 mg%) and folate (26-111mcg%) was observed in individual foods. Bakery products and sweets were found to be poor sources and green leafy vegetables and fruits were good sources of these five vitamins. The differences between ready-to-eat foods and meals consumed during lunch or dinner were prominent for beta-carotene, ascorbic acid, riboflavin and folic acid (P < 0.05). The cooking losses were 34.6, 30, 52.2, 45.9 and 32.2% in case of ascorbic acid, thiamine, riboflavin, beta-carotene and folic acid respectively. Irrespective of whether it is ready-to-eat or a lunch/dinner food item, the contribution of vegetables in the preparations was found to make a marked impact on the vitamin profile. While results justify the concept of a food pyramid, emphasis needs to be given to types of fruits and vegetables rich in vitamins; preferably in their uncooked form, rather than considering their total consumption.

Potential of commonly consumed green leafy vegetables for their antioxidant capacity and its linkage with the micronutrient profile

Green leafy vegetables (GLV) offer a cheap but rich source of a number of micronutrients and other phytochemicals having antioxidant properties. The potential of 30 GLV in the raw and cooked form as natural antioxidant supplements for vegetarian diets was assessed. There was a large variability in the values of antioxidant activity of various GLV extracts in the lipid micelles (1.5–5.6 mM vitamin E/100 g for raw samples and 1.6–3.8 mM vitamin E/100 g for cooked samples). Similar to thiobarbituric acid reactive substances values, the super oxide scavenging ability values also exibited large variation (10.6–55.9), with significantly higher values in the raw state than the cooked state (P<0.001). Omum leaves, radish leaves and lettuce had high values for this index. The range of values for ferrous iron chelating activity was from 9.3 to 65.7 mM EDTA/100 g food material, indicating again a large variability in this assay. Leaves of coriander, amaranthus viridis, colcasia green and drumstick showed high values, while Amaranthus p. Colocasia black and amaranthus red exibited low values. Differences between raw and cooked values were highly significant for all the three indices (P<0.001).

Fortification of vegetarian diets for increasing bioavailable iron density using green leafy vegetables

There is a high prevalence of iron deficiency anaemia in many developing countries today; especially in vegetarian women. The major cause of this state is low bioavailability of nonheme iron from vegetarian diets. An investigation was undertaken to improve bioavailable contents of nonheme iron from vegetarian meals. Forty-eight meals with combinations of roti (unleavened whole cereal pancake) of one of the six cereals and one of the four commonly consumed green leafy vegetables (GLV) along with 35 meals with cereal roti and fruit vegetable/legume were tested for their in vitro dialysability of iron using simulated gastrointestinal conditions and standardised protocol with 59Fe as a tracer. Average bioavailable iron density of GLV-based meals was significantly higher (1.2±0.7 mg /1000 kcal) as against the value in prevailing dietary patterns having cereal-legume or cereal-fruit vegetable combinations (0.36±0.17 mg/1000 kcal, p⩽0.001). Around 31 GLV-based meals were identified as having higher amounts of bioavailable iron density than 0.75 mg/1000 kcal. Thus, one such GLV-based meal per day will increase gross as well as bioavailable iron intake which will help in meeting daily requirements of iron especially for vegetarian women of reproductive age.

Micronutrient Deficiencies as Predisposing Factors for Hypertension in Lacto-Vegetarian Indian Adults

Objective: With the increasing knowledge about the antioxidant potential of many micronutrients such as zinc and vitamin C, their roles in oxidative stress related health disorders have been postulated. This study therefore investigated low micronutrient status as a predisposing factor for hypertension in a traditionally lacto-vegetarian population like Indians. Methods: Micronutrient profile was assessed in 109 hypertensives with age-gender-socio-economic status matched 115 healthy normotensives (30–58 years of age). Food intakes were estimated through a semi-quantitative food frequency questionnaire. Nutrient intakes were then evaluated by previous estimates of cooked foods from our laboratory. Systolic and diastolic blood pressure (SBP, DBP), age, weight, height, waist and hip circumference, occupation, physical activity, smoking habits were recorded. Fasting blood samples were analyzed for hemoglobin, serum level of glucose, triglycerides, total cholesterol, HDL, ceruloplasmin, plasma level of ascorbic acid, folic acid, retinol, erythrocyte glutathione reductase activity coefficient (EGRAC) and erythrocyte membrane zinc. Results: There were no significant differences between protein, fat intakes of normal and hypertensive individuals, though intakes of men were higher than those of women (p < 0.05). Intakes of omega-6 fatty acids were higher (p = 0.08) and omega-3 fatty acids were lower in hypertensive men than normotensive men (p = 0.04). Gender differences were also significant for micronutrient intakes except vitamin C and β-carotene. Intakes of potassium, copper, folic acid and vitamin C were significantly lower in hypertensive individuals than in normotenisves. No significant association was found between occupation or activity level and hypertension (p > 0.2) in these subjects. Conditional logistic regression analysis indicated that intakes of vitamin C, folic acid and zinc were associated with 18% (OR = 1.18, 95% CI:1.08, 1.26), 51% (OR = 1.51, 95% CI 0.94, 2.1) higher odds for hypertension, and 3% lower odds for hypertension (OR = 0.97, 95% CI 0.92, 1.01), respectively. Mean plasma vitamin C and folic acid were significantly higher (p < 0.01), and serum ceruloplasmin and erythrocyte membrane zinc were marginally higher (p = 0.07) in normal than hypertensive subjects. In multivariate linear regression analyses, plasma vitamin C, serum ceruloplasmin and erythrocyte membrane zinc were negatively associated with SBP (p = 0.00001) and plasma vitamin C was negatively associated with DBP (p = 0.0001). Conclusion: Low dietary intakes of vitamin C, folic acid and zinc emerged as the possible risk factors for hypertension. Further, lower levels of plasma vitamin C, erythrocyte membrane zinc and ceruloplasmin were found to be the putative intermediary biomarkers in pathogenesis of hypertension.

The Importance of Nutrition in the Prevention of Ocular Disease with Special Reference to Cataract

Background: The lens is the ocular structure most susceptible to oxidative damage. Antioxidants, micronutrients and phytochemicals have been extensively studied for their possible effects to prevent or delay the progression of various eye diseases. Objectives: A brief overview of the updated literature on the role of antioxidants and micronutrients in the prevention and treatment of ocular diseases is to be presented with an emphasis on cataract. Data Sources: PubMed search and individual papers from journals. Data Synthesis: The review discusses linkages of various micronutrients and antioxidants as well as oxidative stress with cataract. Dietary interventions as strategy for prevention of cataract and other ocular disorders are also reviewed. Conclusions: Consumption of food-based antioxidants like β-carotene lutein and zeaxanthin seem to be useful for the treatment of macular degeneration and cataracts. Supplements of vitamin A, vitamin C, vitamin E and zinc may prevent advanced age-related macular degeneration only in high-risk individuals.

Antioxidant and micronutrient potential of common fruits available in the Indian subcontinent

Considering the scanty information on Indian fruits, 36 commonly consumed fruits were assessed for inhibition of thiobarbituric acid reactive substances, superoxide scavenging activity and ferrous ion-chelating ability along with levels of micronutrients (namely ascorbic acid, β-carotene, riboflavin, thiamine, zinc, copper, iron, manganese, selenium and total polyphenols). Fruits exhibited 24–173% variability for the 13 study parameters. Fresh fruits exhibited 3.5–4 times higher antioxidant capacity than dry fruits. Ascorbic acid was highest in gooseberry (445 mg/100 g), and β-carotene was highest in ripe mango 1,200 mg/100 g. Selenium levels could supply 0–33% of the recommended dietary allowance. There was a strong association between different indices of antioxidant capacity (P<0.001), thiobarbituric acid reactive substances with selenium levels (P<0.01), and superoxide scavenging activity and ferrous ion-chelating ability with zinc content (P<0.05). Results emphasize need for the antioxidant quality of fruit in addition to the quantity of fruit consumption.

Dietary and nutritional biomarkers of lens degeneration, oxidative stress and micronutrient inadequacies in Indian cataract patients ☆

BACKGROUND & AIMS Habitual food and nutrient intakes of 140 Indian cataract patients and 100 age- and sex-matched controls (50-75 years), from high income group and low income groups, were assessed. METHODS Food intake was recorded by food frequency questionnaire and data were examined for linkages with blood/lens parameters of oxidative stress through a case-control study. RESULTS Intake of animal foods and fried snacks was significantly higher while vegetables, green leafy vegetables, fruit, tea and micronutrient intakes were lower in patients than in controls (p<0.001). Lens oxidative stress and opacity showed a significant negative association with fruit intake (p<0.05). Multiple regression analysis indicated association of intakes of iron, beta-carotene, ascorbic acid, tannic acid and inositol pentaphosphate with plasma oxidative stress (p<0.01) and association of intakes of iron, ascorbic acid and inositol triphosphate with lens oxidative stress (p<0.01). Weighted least square regression for lens opacity revealed that intakes of ascorbic acid, folic acid and inositol pentaphosphate explained 59.7% of the total variation (p<0.01). CONCLUSIONS Dietary deficiency of antioxidant micronutrients was greater for patients than controls. Deficiency of beta-carotene, ascorbic acid, folic acid, iron, phytate and polyphenols increased oxidative stress in blood and lens.

Effect of different dietary zinc levels on hepatic antioxidant and micronutrients indices under oxidative stress conditions

Dietary zinc (Zn) status exerts a powerful influence on the degree of oxidative damage caused by free radicals. We examined the effect of dietary Zn variations with oxidative stress (OS) treatment on antioxidant status, liver function, and status of vitamins in male Wistar rats. Oxidative stress was generated by intraperitoneal injections of tert-butyl hydroperoxide; and dietary Zn variations done were Zn deficient, normal, and excess, with 8, 30, and 60 mg Zn per kilogram diet, respectively. After 21-day dietary regimen, the animals were killed; and plasma aspartate aminotransferase, alanine aminotransferase, hepatic antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase), Zn, reduced glutathione, lipid peroxidation (LPO), and hepatic riboflavin, nicotinic acid, and ascorbic acid estimations were done. The alanine aminotransferase and aspartate aminotransferase levels were elevated in rats with OS and Zn-deficient diet, which were restored to normal levels with excess dietary Zn. Hepatic antioxidant enzymes and reduced glutathione levels were significantly decreased with concomitant increase in LPO due to OS induction in animals with Zn-deficient diet. Corresponding enhanced enzyme activities, higher hepatic Zn, and lowered LPO were observed in animals with normal- and excess-Zn diet. A dose-dependent increase in hepatic nicotinic acid accumulation was observed as the dietary Zn level increased from deficient to excess; however, there was no influence on riboflavin and ascorbic acid status. The results suggest that Zn may have a therapeutic potential in treatment of oxidative liver damage along with enhanced nicotinic acid absorption.

In vitro dialyzability using meal approach as an index for zinc and iron absorption in humans.

With a standardized protocol under simulated gastrointestinal conditions,65Zn and59Fe dialyzability was measured for 38 diets from 7 different published studies on human absorption. The compositions of these diets were available in the form of the amounts of food ingredients used for breakfast, lunch, and dinner. Considering each of these types as a separate meal, percent dialyzability was measured. The weighted average of breakfast, lunch, dinner, and snacks, if any, was taken to represent the entire day’s bioavailability. The correlation between in vitro percent dialyzability and reported human absorption was 0.92 for zinc and 0.96 for iron and both were statistically significant (p = 0.0001). The prediction equations for zinc and iron were obtained asy = -0.7718 + 1.1038x andy = 0.3197 + 0.9084x, respectively. This indicated that in vitro dialyzability using the meal approach can be used as an index with good discriminating power for different levels of human absorption.

Factors Influencing Zinc Status of Apparently Healthy Indians

Objectives: To identify dietary, environmental and socio-economic factors associated with mild zinc deficiency, three zinc status indices; erythrocyte membrane zinc (RBCMZn), plasma zinc and super oxide dismutase (SOD) were assessed in free living and apparently healthy Indian population. Methods: Dietary patterns of 232 men and 223 women (20–65 yr) from rural, industrial and urban regions of Western India were evaluated by food frequency questionnaire. RBCMZn was estimated using atomic absorption spectrometry, hemoglobin and serum ceruloplasmin by spectrophotometer. On a sub sample (48 men and 51 women) plasma zinc and SOD were also assessed. Results: Mean RBCMZn was 0.5 ± 0.1 μmols/g protein with 46% individuals showing zinc deficiency. Mean plasma zinc was 0.98 ± 0.12 μg/mL with 25% men and 2.5% women having values below normal range. Mean SOD was 0.97 ± 0.1 (u/mL cells). A significant positive correlation was observed between intakes of green leafy vegetables, other vegetables and milk products with RBCMZn status (p < 0.05). But these were not correlated with plasma zinc (p > 0.2). Cereal and legume intakes were negatively correlated with RBCMZn (p < 0.05) but positively correlated with plasma zinc (p < 0.05) and not correlated with SOD (p > 0.2). Fruit and other vegetable intake were positively correlated with SOD (p < 0.05) alone. Logistic regression analyses revealed that RBCMZn was positively associated with intakes of β-carotene, zinc and environmental conditions and negatively associated with family size (p < 0.05). Plasma zinc indicated positive association with zinc, thiamin and riboflavin intakes (p < 0.05) and SOD showed negative association with iron and family size. Conclusion: RBCMZn was a more sensitive indicator of long-term zinc status than plasma zinc and SOD. Prominent determinants of zinc status were intakes of beta-carotene and zinc along with environmental conditions and family size.