Analysis of Fluoride Content of Different Types of Salts Used in the Indian Diet: An In Vitro Study.

Discussion

Every day, we ingest fluoride from various sources. Drinking water contains a fluoride concentration of 0.5-1 ppm [24]. The commonly consumed foods in our diet also have varying fluoride levels, which can be beneficial when consumed appropriately but detrimental if not managed carefully. Among dietary sources, tea stands out as one of the highest contributors to fluoride intake because it accumulates fluoride effectively [25]. A cup of tea has a fluoride concentration of 0.07 to 1.5 ppm [26]. Fruit consumption averages 0.06 ppm, while meat, fish, and poultry contribute to approximately 0.22 ppm. The average consumption of fluorides from oils and fats is 0.25 ppm, which is similar to that of dairy products. Leafy vegetables contribute to 0.27 ppm, whereas sugar and adjunct chemicals are around 0.28 ppm. Fluoride content in root vegetables is approximately 0.38 ppm, while the average consumption of grain and cereal products contributed to 0.42 ppm. Vegetables such as potatoes and legumes provide around 0.50 ppm of fluoride [6].

Salt is an essential part of the Indian diet. The variability of fluoride content in different types of edible salt is a cause for concern, with limited literature available globally on this subject. Researchers have studied the fluoride concentration in table salt to some extent, but information about other commercially marketed salt varieties is scarce. Previous research has shed light on this issue, highlighting notable variations in fluoride content among different salt brands [22,23,26-29].

As per our analysis, various types of edible salts have fluoride levels, ranging from 15.05 ppm to 62.5 ppm. For adults, the recommended daily tolerable upper intake level (UL) of fluoride is 10 mg [26]. This surpasses the maximum permissible limits of fluoride consumption. Salt, which is an inevitable component of our daily diet, when used in conjunction with other food sources can adversely affect adult human health. Long-term ingestion of small amounts of fluoride results in chronic fluoride toxicity, which has a significant impact on dental and skeletal health. Most of us are unaware of this daily excess of fluoride consumption and its potential health risks. Therefore, we should meticulously regulate fluoride intake from various dietary sources to minimize foreseeable health hazards.

Brazil conducted a study that evaluated 11 brands of table salt, of which nine had fluoride. The fluoride concentrations ranged from below the Nicaraguan legislation’s prescribed limit of 200-225 mg F/kg to within it. Two fluoridated brands met the legal requirements, while the remaining five fell below the specified range. Additionally, traces of fluoride were observed in two non-fluoridated brands, pointing out discrepancies in labelling or manufacturing processes [22]. In our study, none of the salts had a mention of fluoride in the Nutrition Facts labelling the packaging of the salt. This probably could be due to the absence of any regulation that mandates its display in India.

Similarly, in Bogota, Colombia, a study analyzed 28 brands of table salt and found a mean fluoride concentration of 133.8 ppm F, with values ranging widely from 4.8 to 225.7 ppm F. Notably, the majority of samples (71%) had fluoride levels below those recommended by the national program for salt fluoridation in Colombia, indicating potential inadequacies in the fluoridation process or variability in product formulation [23]. In four municipalities of Colombia, another study revealed that the average fluoride concentration of table salt fell below the lower limit (180-220 ?g/g) set by the Colombian regulation [27].

Furthermore, a study examining 44 table salt brands in Mexico found significant discrepancies between the labelled fluoride content and actual concentrations. While the Mexican regulation stipulates a fluoride range of 200-250 ppm F, only a few samples fell within this range, with the majority either below or above it. Alarmingly, the salt industry needs stricter quality control measures and accurate labelling practices as 92% of the samples had incorrect fluoride content labels [28].

A pilot study in Lima, Peru, evaluated the fluoride concentration in salt packages marketed using a standardized protocol. The results showed that the mean fluoride concentration in four packages was in line with the Peruvian regulation, but in three packages it was lower. We observed variability in fluoride concentration within and among brands, ranging from 72.0 to 1,449.7 mg F/kg [29].

In our study, the fluoride levels in edible salts were well within the prescribed limits for fluoride intake. However, black salt, commonly used in Northern India, Pakistan, and Bangladesh, had a comparatively high concentration of fluoride. There is a lack of scientific literature to validate the observations, though some sources have pointed out increased fluoride concentrations in this type of salt [30-32]. Himalayan pink salt had low levels of fluoride. Grey literature sources, which mention traces of fluoride in pink salts [18,33], also corroborate this finding.

This study adds to a relatively unexplored area of fluoride concentrations in one of the commonest ingredients used in the Indian diet and also sheds light on the need for fluoride labelling in food products.

Limitations

This study, which was exploratory in nature, included only two brands of salt from each type of salt. To account for any variability, further research could include more brands and increase samples. Fluoride estimation was conducted using spectrophotometric methods using laboratory-based devices. Fluoride levels estimated using ion-selective electrodes and ion chromatography could yield more accurate results.

Conclusions

Fluoride content in different types of edible salt varied significantly. The mean fluoride levels were highest in black salt, followed by rock salt, pink salt, and iodized salt. A statistically significant difference was found in fluoride concentration between the different types of salt. Differences in concentration were more significant between iodized salt-black salt and Himalayan pink salt-black salt pairs. No significant differences were found between two brands of the same salt, except for iodized salt, suggesting that fluoride concentration depends on the source. However, the concentration of fluoride was well within the prescribed limits required to cause fluorosis. This research emphasizes the need for understanding the fluoride concentration in various salt varieties to mitigate health hazards. It also emphasizes the need to monitor fluoride levels in edible salts and establish standardized guidelines to guarantee customer safety and promote oral health advantages.

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