Effect of Cooking on the Nitrate Levels in Vegetables

Fletcher, J. R.; Law, S. J.; Walters, A. H.

doi:10.1177/026010608700500209

Cited by 8 publications

(3 citation statements)

References 6 publications

(3 reference statements)

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“…To inform the composition of the vegetable smoothie beverages administered in this study, the NO 3 and SCNcontent of a variety of vegetables was assessed prior to experimental testing. These preliminary analyses revealed that garden peas were low in both NO 3 -(~ 0.8 mg/100 g) and SCN -(< 0.1 mg/100 g), spinach and rocket were high in NO 3 -(~ 143.0 and 360.5 mg/100 g, respectively) and low in SCN -(both < 0.1 mg/100 g), and the inner leaves of a cabbage were high in SCN -(~ 5.0 mg/100 g) and low in NO [22] and NO 3 - [29]. A 30 mL aliquot was obtained from each of the four vegetable smoothies from which subsequent 1.5 mL aliquots were collected and analyzed to determine the NO 3 and SCNcontent of the vegetable smoothie beverages (see below for further details).…”

Section: Supplementation Proceduresmentioning

confidence: 95%

Lowering of blood pressure after nitrate-rich vegetable consumption is abolished with the co-ingestion of thiocyanate-rich vegetables in healthy normotensive males

et al. 2018

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A diet rich in vegetables is known to provide cardioprotection. However, it is unclear how the consumption of different vegetables might interact to influence vascular health. This study tested the hypothesis that nitrate-rich vegetable consumption would lower systolic blood pressure but that this effect would be abolished when nitrate-rich and thiocyanate-rich vegetables are co-ingested. On four separate occasions, and in a randomized cross-over design, eleven healthy males reported to the laboratory and consumed a 750 mL vegetable smoothie that was either: low in nitrate (∼0.3 mmol) and thiocyanate (∼5 μmol), low in nitrate and high in thiocyanate (∼72 μmol), high in nitrate (∼4 mmol) and low in thiocyanate and high in nitrate and thiocyanate. Blood pressure as well as plasma and salivary [thiocyanate], [nitrate] and [nitrite] were assessed before and 3 h after smoothie consumption. Plasma [nitrate] and [nitrite] and salivary [nitrate] were not different after consuming the two high-nitrate smoothies, but salivary [nitrite] was higher after consuming the high-nitrate low-thiocyanate smoothie (1183 ± 625 μM) compared to the high-nitrate high-thiocyanate smoothie (941 ± 532 μM; P < .001). Systolic blood pressure was only lowered after consuming the high-nitrate low-thiocyanate smoothie (-3 ± 5 mmHg; P < .05). The acute consumption of vegetables high in nitrate and low in thiocyanate lowered systolic blood pressure. However, when the same dose of nitrate-rich vegetables was co-ingested with thiocyanate-rich vegetables the increase in salivary [nitrite] was smaller and systolic blood pressure was not lowered. These findings might have implications for optimising dietary guidelines aimed at improving cardiovascular health.

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Section: Supplementation Proceduresmentioning

confidence: 95%

Lowering of blood pressure after nitrate-rich vegetable consumption is abolished with the co-ingestion of thiocyanate-rich vegetables in healthy normotensive males

et al. 2018

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“…SIK, 1980). The nitrate content in cooked dishes was assumed to be reduced by 50% on account of its thermolability (Fletcher et a/., 1987). For each dietary constituent, quartiles were established according to the distribution among the controls.…”

Section: Methodsmentioning

confidence: 99%

Nutrients and gastric cancer risk. A population‐based case‐control study in Sweden

Hansson

Nykén

Beagström

et al. 1994

Intl Journal of Cancer

124

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A population-based case-control study of gastric cancer was conducted in areas with contrasting incidence rates in Sweden. Face-to-face interviews were carried out with 338 (74.1%) of all eligible cases and 679 (77.3%) of the selected controls. Consumption of selected nutrients during adolescence and 20 years prior to interview was estimated, together with life-time intake of vitamin supplements. Ascorbic acid and beta-carotene had an unequivocal protective effect, but alpha-tocopherol and nitrate were also negatively associated with gastric-cancer risk. In a multivariate analysis including all of these factors, only ascorbic acid remained a significant protective factor. The only macronutrient positively associated with the risk of gastric cancer was fat: intake 20 years prior to interview, but not during adolescence, was found to have a significant impact. Supplementation with vitamins almost halved the risk after adjustment for dietary intake of the corresponding vitamins. While the protective effect of vitamin C and beta-carotene could conceivably be ascribed to other agents in the diet, the strong negative association between supplementation with vitamin C and risk of gastric cancer supports the hypothesis of a protective role of this anti-oxidant.

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“…In response, various international organizations have set specific guidelines restricting additives in foods and the amount permitted in drinking water. However, even though it is estimated that nitrates found in vegetables account for 87% of the nitrates in a normal diet (NAS, 1981), the only countries to establish legal limits on them are The Netherlands and Switzerland (Fletcher et al, 1987).…”

Section: Introductionmentioning

confidence: 99%