**3.3 Salicylates from food**

It was unclear whether sufficient salicylic acid could be obtained from dietary sources to influence health and disease with estimated daily intakes ranging from 0.4 to 200 mg/day [13, 22, 23]. That range reflected the disparate information available on the salicylate content of foods.

Native Indian volunteers, living in a rural area near Chennai, had been recruited

**Median (μmol/L) Range (μmol/L)**

for another study as representative of that community for health lifestyle and nutritional status. They had a diet of locally grown vegetables, grains and pulses flavoured with spices and herbs. The serum from these 21 South Indians had a median SA concentration of 0.263 μmol/L (range 0.05–0.64—significantly higher (2.5- to 3.5-fold higher) than those found in the sera of the other groups reported above [24]; p < 0.001 against both vegetarians and non-vegetarians by Mann– Whitney *U* test) [27]. Summarised and compared with other results below in

Vegetarians n = 37 0.110 0.04–2.47 Non-vegetarians n = 39 0.070 0.02–2.00 Southern Indian villagers n = 21 0.263 0.05–0.64 75 mg aspirin takers n = 14 10.03 0.23–25.4

Given that SA is a stress hormone in plants we can anticipate that locality, varietal and growing conditions could affect total salicylate content at harvesting before any variability in processing conditions and storage effects. Wide reported ranges for different brands assayed using standard conditions are therefore not particularly surprising. For example the SA content of five brands of orange juice

*Tables 1 and 2—with modification—from Ref. [28]—https://pubs.acs.org/doi/abs/10.1021/jf800974z?src=recsys:*

Usually an open question but, given the above considerations, probably not in respect of SA content. Thus the median SA contents in organic and non-organic vegetable soups were 117 ng/g (range 8–1040) and 20 ng/g (range 0–248) respectively; the median between the difference groups was 59 ng/g (95% confidence intervals 18–117 ng/g), p = 0.032 by Mann Whitney *U* test [30]. Consider also constraints of drought, other physical stresses and non-availability of pest control

Clearly sample selection and methodology will affect estimates of SA content in the diet. Using the assay methodology our group developed [27, 30] to supplement published results, Wood et al. [29] prepared a comprehensive dietary database. They filtered published results of dietary constituent total salicylate content by specific criteria. Food items had to be randomly selected and purchased from various commercial outlets at different times of the year; food samples to be prepared using standard domestic practices; optimised sample extraction and hydrolysis conditions were to be clearly described or cited, and salicylate determination to be based on modern techniques of HPLC and mass spectrometry with validation

obtained from Scottish retailers ranged from 0.47 to 3.01 mg/kg [29].

which inevitably prevail in many emergent nations.

**Table 1**.

**3.4 SA in food**

*Results in Man [24, 27].*

**Table 1.**

*Limit of detection of the method = 0.005 μmol/L.*

*Salicylic Acid Sans Aspirin in Animals and Man DOI: http://dx.doi.org/10.5772/intechopen.91706*

*further permissions regarding use of the content should be directed to the ACS.*

*3.4.1 Organic or not?*

*3.4.2 A Scottish overview*

**181**

Comparison, in the serum of subjects not taking aspirin, of SA levels in 37 vegetarians and 39 non-vegetarians found higher concentrations in the former [24]. That study revealed median concentrations of 0.11 (range 0.04–2.47) μmol/L and 0.07 (range 0.02–0.20) μmol/L respectively: the median of the difference was 0.05 μmol/L (95% confidence interval for difference 0.03–0.08; p < 0.0001). The median SA level measured in serum from 14 patients on aspirin 75 mg/day was, at 10.03 (range 0.23–25.40) μmol/L, significantly higher. However there was overlap in serum SA concentrations between the vegetarians (8 higher than lowest low dose aspirin) and patients taking aspirin (6 below the highest vegetarian value). These findings should be considered in light of the inhibition of COX2 transcription that has been shown to occur at SA levels as low as 0.1 μmol/L [4].

In a further study the urinary excretion of SA and SU was assessed in 24 h samples from 27 non-vegetarians, 21 vegetarians and 40 patients taking 75 or 150 mg aspirin/day [25]. For SU, the principle urinary salicylate, vegetarians excreted significantly more than the non-vegetarians (median 11.01; range 4.98– 26.60 μmol/24 h compared with 3.91; range 0.87–12.23 μmol/24 h) but these amounts were significantly lower than those excreted by patients on aspirin. Significantly more SA was excreted by the vegetarians (median 1.19; range 0.02– 3.55 μmol/24 h) than by the non-vegetarians (median 0.31; range 0.01–2.01 μmol/ 24 h). The median amounts of SA excreted by the vegetarians and the patients taking aspirin were not significantly different. These values were comparable to those found earlier, using less specific methodology, in a group of drug free volunteers on a variety of diets [13].

#### *3.3.1 The spice of life*

Awareness that certain spices had been reported [22] to contain especially high concentrations of SA and the reported very low incidence of colorectal cancer in rural India [26] led to our particular assessment of spices.

Spices, Indian cooked dishes and blood and urine samples taken after ingestion of a test meal were investigated for their salicylate content. Total salicylate content determination required a preliminary alkali treatment step before our standard extraction [27] as, in plants, phenolic glycosides and carboxylic esters are present as well as the "free" phenolic acid. Our standard assay conditions for SA were then applied. All samples of spices and cooked meals examined contained SA (up to 1.5 wt%); cumin, turmeric, red chilli powder, paprika and cinnamon were especially rich sources. Our measurements were considerably higher than those previously published [22]. That was attributed to previously suboptimal extraction, chromatographic separation and detection [27]. The identity of the SA fractions (on HPLC) from cumin, paprika and turmeric was confirmed, after elution and esterification, by GC–MS of their methyl esters.

The potential bioavailability of SA derived from a prepared meal was assessed in a single aspirin free volunteer after a 10 h fast. Consumption of 545.3 g of a cooked vegetable dish (shown by aliquot assay to contain 94.03 g of total salicylates) was followed by regular blood and urine collection over 6 h. Serum SA doubled within 1.5 h and urinary SU increased 20-fold during that time.

*Salicylic Acid Sans Aspirin in Animals and Man DOI: http://dx.doi.org/10.5772/intechopen.91706*

Native Indian volunteers, living in a rural area near Chennai, had been recruited for another study as representative of that community for health lifestyle and nutritional status. They had a diet of locally grown vegetables, grains and pulses flavoured with spices and herbs. The serum from these 21 South Indians had a median SA concentration of 0.263 μmol/L (range 0.05–0.64—significantly higher (2.5- to 3.5-fold higher) than those found in the sera of the other groups reported above [24]; p < 0.001 against both vegetarians and non-vegetarians by Mann– Whitney *U* test) [27]. Summarised and compared with other results below in **Table 1**.


*Limit of detection of the method = 0.005 μmol/L.*

*Tables 1 and 2—with modification—from Ref. [28]—https://pubs.acs.org/doi/abs/10.1021/jf800974z?src=recsys: further permissions regarding use of the content should be directed to the ACS.*

**Table 1.** *Results in Man [24, 27].*

### **3.4 SA in food**

**3.3 Salicylates from food**

available on the salicylate content of foods.

volunteers on a variety of diets [13].

fication, by GC–MS of their methyl esters.

*3.3.1 The spice of life*

**180**

It was unclear whether sufficient salicylic acid could be obtained from dietary sources to influence health and disease with estimated daily intakes ranging from 0.4 to 200 mg/day [13, 22, 23]. That range reflected the disparate information

*Drug Repurposing - Hypothesis, Molecular Aspects and Therapeutic Applications*

Comparison, in the serum of subjects not taking aspirin, of SA levels in 37 vegetarians and 39 non-vegetarians found higher concentrations in the former [24]. That study revealed median concentrations of 0.11 (range 0.04–2.47) μmol/L and 0.07 (range 0.02–0.20) μmol/L respectively: the median of the difference was 0.05 μmol/L (95% confidence interval for difference 0.03–0.08; p < 0.0001). The median SA level measured in serum from 14 patients on aspirin 75 mg/day was, at 10.03 (range 0.23–25.40) μmol/L, significantly higher. However there was overlap in serum SA concentrations between the vegetarians (8 higher than lowest low dose aspirin) and patients taking aspirin (6 below the highest vegetarian value). These findings should be considered in light of the inhibition of COX2 transcription that

In a further study the urinary excretion of SA and SU was assessed in 24 h samples from 27 non-vegetarians, 21 vegetarians and 40 patients taking 75 or 150 mg aspirin/day [25]. For SU, the principle urinary salicylate, vegetarians excreted significantly more than the non-vegetarians (median 11.01; range 4.98– 26.60 μmol/24 h compared with 3.91; range 0.87–12.23 μmol/24 h) but these amounts were significantly lower than those excreted by patients on aspirin. Significantly more SA was excreted by the vegetarians (median 1.19; range 0.02– 3.55 μmol/24 h) than by the non-vegetarians (median 0.31; range 0.01–2.01 μmol/ 24 h). The median amounts of SA excreted by the vegetarians and the patients taking aspirin were not significantly different. These values were comparable to those found earlier, using less specific methodology, in a group of drug free

Awareness that certain spices had been reported [22] to contain especially high concentrations of SA and the reported very low incidence of colorectal cancer in

Spices, Indian cooked dishes and blood and urine samples taken after ingestion of a test meal were investigated for their salicylate content. Total salicylate content determination required a preliminary alkali treatment step before our standard extraction [27] as, in plants, phenolic glycosides and carboxylic esters are present as well as the "free" phenolic acid. Our standard assay conditions for SA were then applied. All samples of spices and cooked meals examined contained SA (up to 1.5 wt%); cumin, turmeric, red chilli powder, paprika and cinnamon were especially rich sources. Our measurements were considerably higher than those previously published [22]. That was attributed to previously suboptimal extraction, chromatographic separation and detection [27]. The identity of the SA fractions (on HPLC) from cumin, paprika and turmeric was confirmed, after elution and esteri-

The potential bioavailability of SA derived from a prepared meal was assessed in a single aspirin free volunteer after a 10 h fast. Consumption of 545.3 g of a cooked vegetable dish (shown by aliquot assay to contain 94.03 g of total salicylates) was followed by regular blood and urine collection over 6 h. Serum SA doubled within

has been shown to occur at SA levels as low as 0.1 μmol/L [4].

rural India [26] led to our particular assessment of spices.

1.5 h and urinary SU increased 20-fold during that time.

Given that SA is a stress hormone in plants we can anticipate that locality, varietal and growing conditions could affect total salicylate content at harvesting before any variability in processing conditions and storage effects. Wide reported ranges for different brands assayed using standard conditions are therefore not particularly surprising. For example the SA content of five brands of orange juice obtained from Scottish retailers ranged from 0.47 to 3.01 mg/kg [29].

#### *3.4.1 Organic or not?*

Usually an open question but, given the above considerations, probably not in respect of SA content. Thus the median SA contents in organic and non-organic vegetable soups were 117 ng/g (range 8–1040) and 20 ng/g (range 0–248) respectively; the median between the difference groups was 59 ng/g (95% confidence intervals 18–117 ng/g), p = 0.032 by Mann Whitney *U* test [30]. Consider also constraints of drought, other physical stresses and non-availability of pest control which inevitably prevail in many emergent nations.

### *3.4.2 A Scottish overview*

Clearly sample selection and methodology will affect estimates of SA content in the diet. Using the assay methodology our group developed [27, 30] to supplement published results, Wood et al. [29] prepared a comprehensive dietary database. They filtered published results of dietary constituent total salicylate content by specific criteria. Food items had to be randomly selected and purchased from various commercial outlets at different times of the year; food samples to be prepared using standard domestic practices; optimised sample extraction and hydrolysis conditions were to be clearly described or cited, and salicylate determination to be based on modern techniques of HPLC and mass spectrometry with validation

and quality assurance methods summarised. Combination of such published data, which met these criteria, together with their in-house analyses resulted in a database of 27 types of fruit, 21 vegetables, 28 herbs, spices and condiments, 2 soups and 11 beverages—expressed as median values to reflect the non-normal distribution of the results.

Subsequently dietary intake was assessed by applying this salicylate database, using a validated questionnaire, to 237 healthy individuals age range (17–72) from Aberdeen [29]. Estimated median total salicylate intakes for men and women were 4.42 and 3.16 mg/day respectively, a gender difference not sustained when corrected for energy. Primary food sources of salicylates as shown in **Figure 2** were alcoholic beverages (22%), herbs and spices (17%), fruits (16%), non-alcoholic beverages including fruit juice (13%), tomato-based sauces (12%) and vegetables (9%). Salicylate intake was significantly (p < 0.001) and positively associated with intakes of fibre, potassium, vitamin C and alcohol!
