© Borgis - New Medicine 2/2006, s. 30-34
Sylwia Merkiel, Wojciech Chalcarz
Modifying salt intake to prevent hypertension
Department of Food and Nutrition, University School of Physical Education, Poznań, Poland
Head of Department: Prof. Wojciech Chalcarz, MD, PhD
Summary
Summary
Reduction in salt intake is one of the methods of effective prevention of hypertension epidemic. The surest way to attain this aim is to introduce the National Hypertension Prevention Programme, which should include both population strategy, aimed at the whole society, and individual strategy, aimed at a single person. Putting the knowledge on salt preferences into practice ought to play a vital role.
Introduction
For 5 million years our predecessors were on a completely salt-free diet. Their organisms got used to regulate water balance and electrolyte equilibrium with the minimum amounts of salt naturally contained in food. Adding salt to food began 5-10 thousand years ago. Because the human organism was accustomed to save salt whose supply had been relatively little, the sudden – considering evolution – increase in its intake resulted in problems in the excretion of its excess. It resulted in a common blood pressure increase [1].
Currently, salt plays a very important role for human feeding behaviours. It influences the taste of products and dishes [2, 3], delivers sodium and chloride ions necessary to keep the systemic electrolyte equilibrium [4] and brings a lot of trace elements needed by the human [5, 6], provided he/she consumes non-refined salt. In a majority of countries salt is enriched with iodine. It is also considered to enrich it with iron [6]. Salt is also commonly used by food industry engineers [3, 7, 8] as a preservative and product taste improver [3].
Today, salt intake is higher by 10-20 times than it was 5-10 thousand years ago. The human body is genetically pre-programmed for salt intake at the amount of 1 g per day [1], while in contemporary world its intake is several or even more than ten times higher [4].
If salt was neutral to human body, then both feeding behaviours concerning this food stuff and using it by food producers could be described only as a sociological phenomenon. However, salt is a biologically active ingredient and consequently, non-neutral to our body and health. Despite many studies concerning this problem, many people do not realize the impact of salt on human organism and the necessity to reduce its intake.
The aim of this paper was to present the connection between salt intake and hypertension and showing the possibilities to fight against this disease by reducing its consumption.
Salt intake and hypertension
A diet containing the high amount of sodium increases the blood pressure, while abusing salt leads to hypertension [9, 10, 11, 12, 13]. Hypertension causes strokes and myocardial infarctions [14, 15, 16]. Diets rich in vegetables, fruit and low-fat dairy products, i.e. recommended in the prevention of hypertension, but at the same time containing a large amount of salt results in keeping blood pressure on a higher level than while using the same diet with low salt content [17, 18]. Reducing salt intake usually results in blood pressure drop, thus reducing the risk of stroke or myocardial infarction [19, 20, 21, 22, 23, 24, 25, 26, 27]. Decreasing salt intake by 3 g/24h resulted in systolic pressure drop by 3.6 to 5.6 mmHg in patients with hypertension and by 1.8 to 3.5 mmHg in healthy persons, whereas diastolic pressure by 1.9 to 3.2 mmHg and by 0.8 to 1.8 mmHg in hypertensive and normotensive persons, respectively [22]. This effect can be doubled by reducing salt intake by 6 g/24h, and even tripled by reducing intake by 9 g/24h [22]. The positive effects of salt intake reduction are especially clear in persons aged 50 to 65. In this age group the reduction in salt intake by 3 g per day caused an average drop in systolic blood pressure by as much as 10 mmHg [24].
Reducing salt intake can contribute to considerable improvement in people health condition. Scientists found that if in the scale of whole population pressure drop amounted to 2 mmHg, it would result in the drop in hypertension incidence by as many as 17% [25]. Reducing sodium intake by 100 mmol/day can prevent as many as 20% of hypertension incidents [28]. It is estimated that reducing salt intake in the UK by 9 g/day would decrease the incidence of stroke by 1/3, whereas the incidence of ischaemic heart disease would drop by approximately 1/4, which would prevent 52 thousand deaths per year caused by those diseases [22].
It should be kept in mind that reducing blood pressure by applying drug treatment provided comparable effects to changes resulted from reducing salt intake [13, 29], which shows that low-salt diet has an important role in preventing and treating hypertension [30]. When it is impossible to eliminate drugs completely, a proper diet can effectively support the pharmacological treatment of hypertension. In aged persons reducing sodium intake by only 40 mmol/day resulted in 30 percent drop in the demand for drugs [28]. It should be noted that pharmacological treatment can be far more effective if it is accompanied by non-pharmacological treatment: reduction in salt intake, physical exercise and body mass reduction [31].
The reduction of salt intake brings also some financial benefits [28]. Reducing daily consumption of salt by 6 g per person in the population of Norwegians would bring the society 118 million dollars of savings as a result of decrease in treatment expenses [32].
The problem of salt intake amount in social, economic and medical context cannot be omitted in Poland either. In 2001 we consumed 9.21 g of salt per person per day [33], while levels defined by WHO show that its daily intake should not exceed 6 g [34]. Studies performed in our Department show that average salt consumption by persons living in old age homes in Wielkopolska amounted to almost 10 g/day [35], whereas pre-school (kindergarten) children from Nowy Sącz exceeded 7 g/day. These results are really alarming especially in the case of children who according to the recommendations of Consensus Action on Salt and Heath [36] should not take more than 3 g/day. These limits were exceeded considerably also in the studies on Polish teenagers [37, 38], students [39, 40] and the aged [35, 41, 42]. As it is clearly seen, the problem refers to the whole Polish population irrespective of age and results from deeply rooted, passed from generation to generation bad feeding habits. It is estimated that as many as 46 percent of men and 36 percent of women suffer from hypertension [43]. Every year about 70 thousand people in Poland die of stroke, whereas about 100 thousand die of myocardial infarction [43]. Therefore, the reduction of salt intake in Poland is really necessary.
Methods of salt intake reduction in population-based and individual approach
In order to reduce salt intake throughout Poland, it would be necessary to create, similarly as the National Cholesterol Prophylaxis Programme [44], the National Hypertension Prevention Programme. It should include a population strategy aimed at the entire society and an individual strategy aimed at single persons.
The aim of the population strategy would be to decrease the incidence of hypertension in the entire population. To achieve this, it would be necessary to promote the reduction of salt intake as well as to introduce some legal restrictions concerning the use of salt in food products by producers and encouraging them, first of all by financial impulses, to produce low-sodium food. It would be important to impose the obligation to indicate saltiness on the labels of salt, as its saltiness depends on its chemical composition. It should be also important to promote physical activity and indicate the importance of avoiding obesity [45].
Without the above-mentioned legal regulations concerning salt content in products and meals, it would not be possible to reduce salt intake, as salt added by people while eating or preparing dishes is only a fragment of total salt consumption. The majority of salt comes from factory prepared products and dishes salted during their production process [46, 47, 48, 49]. It is estimated that in Western European populations the salt consumed with everyday food in 75-80% comes from ready made food products [28]. Large amounts of salt are added to fast food type products or any sorts of powdered instant soups and sauces. In today´s ”busy” society these products are very popular because of time saving and we are encouraged to use them by ubiquitous advertisements that have an extremely strong impact on children [50, 51, 52]. In addition, the salt supply is increased by basic food products, being present in everyday human diet such as for example bread [34, 53].
Many producers explain their objection to salt reduction in their products by the anxiety of making them less popular among customers and as a result, sales drop. Although, the truth is that producers add salt to food products because of its ability to bind water (hygroscopic properties)[3, 54]. Thanks to this, it is possible to cheaply increase the product weight. In addition, the more salt consumed the more beverages drunk and this is probably the reason why some non-alcoholic beverages producers are also the owners of companies producing salty snacks [54].
The studies performed show that reducing salt content will not result in any reduction of customer acceptance for products and consequently, sales drop. Researchers observed that decreasing the sodium content in white bread by 25% did not reduce customer acceptance for this product [46]. Taste assessment did not differ much among persons tasting bread with salt content lower by 10% and 20% [53]. Similar results were obtained in the studies concerning taste values and customer acceptance for soups with various salt content, sodium monoglutamate and calcium diglutamate. The studies showed that soups with salt content reduced both to 60% and to 30%, but supplemented by calcium diglutamate received the same or higher marks in terms of preferences and taste richness, intensity and natural values as soups with standard salt content [55].
The preparation and implementation of population strategy can have a positive and significant impact on our population, which is confirmed by experiences in other countries. A study performed in two selected Portugal cities unambiguously showed the efficiency of the introduced educational programme concerning reducing salt intake and blood pressure [56]. The average blood pressure of the city inhabitants where the programme was introduced decreased considerably, while in the control city diastolic pressure in inhabitants did not change, whereas systolic pressure increased. The differences observed between the two cities were statistically significant [56].
This has been also confirmed by wide scale studies performed in Finland. To increase the effect of salt intake reduction in population, they engaged health service, schools, and health supporting organizations, supermarkets, foodstuff industry and media. In legislation they defined the level of salt content for low and high-sodium products and they specified the limit for salt concentration in food products. In addition, they defined the term ”low salt content” placed on labels and obliged producers to attach the inscription: ”high salt content” on labels, if its level was higher than permitted by law. This project was initially introduced in only one region, after five years it covered the whole country. As a result, within 20 years a constant change in feeding behaviour of Finnish people was achieved along with reducing the incidence of ischaemic heart disease by as much as 65% in the age group of 35 to 64 [57, 58, 59].
The individual strategy should include some primary prevention, based first of all on modifying the nutrition consciousness and encouraging people to physical activity throughout their lives, it should also include some secondary prevention. Special role should be played by health care personnel. They should know how to modify salt and salted product preferences, how to specify low-sodium diets and they also should treat blood pressure measurement as a part of standard examination for all patients.
While considering the individual strategy, we should take into account that salt is a spice being most frequently added to dishes and consumers here do not follow any health recommendations as taste is the most important thing for them [60]. And it is taste value that is the most important thing that determines food preferences and human feeding choices [61, 62, 63]. It is the failure to give up favourite food products and dishes is the most frequent obstacle on the way to healthy nutrition [64, 65]. As a result, an effective strategy in preventing hypertension can make promoting the preferences for low-salt products, which results in healthy low salt intake.
The human food preferences are shaped as early as in the prenatal and infancy period. Studies showed that the loss of electrolytes by a pregnant woman caused by frequent vomits can increase the willing to consume salt by their child [66, 67]. Infants whose mothers did not vomit or vomited very rarely during the first 14 weeks of pregnancy consumed significantly less salty solutions and showed statistically significant higher aversion to solutions with higher salt content as compared with infants whose mothers experienced frequent vomits during gestation [66]. It has been found that there is a connection between salt preference in teenagers and adults and vomit occurrence in their mother during pregnancy [67, 68]. The children of women experienced moderately and frequent vomits consumed more salt than the offspring of women who almost did not vomit in pregnancy. In addition, these children preferred snacks with high salt content [68].
Similarly, the disorders in water balance and electrolyte equilibrium in infancy resulted from recurring vomiting or diarrhoea, caused high salt feeding preferences at later life periods, increasing the salt content in everyday diet [67]. Adding salt to dishes, preferred salt concentration in soup and eating salty snacks was higher in teenagers, who experienced vomiting and suffered from diarrhoea in infancy, while salt preference was the higher the more frequent occurred the above-mentioned water balance and electrolyte equilibrium reasons [67]. Scientist observed a significant correlation between the fact of enjoying salty products and the kind of formula they were fed with in infancy [69]. The teenagers fed with salt-free nutrients did not enjoy products with low salt content (among others some fruit, vegetables and rice or milk), whereas they liked salty products more than their siblings fed with a formula containing sodium chloride. Furthermore, the teenagers more frequently added salt to dishes before tasting and to non-typical dishes, which their siblings did less frequently [69].
The above-mentioned facts show that it is, first of all, mother who decides about future child´s feeding habits. By preferring low salt intake, taking care of water balance and electrolyte equilibrium during pregnancy and in infancy period as well as by selecting a proper nutrient she can contribute to modifying healthy low salt preferences in her child being very advantageous in hypertension prevention.
However, salt preferences can be also changed in adults, as the preferred salt content in consumed food products is determined by its intake in our everyday diet. An increase in salt intake increases their preferences, while decrease reduces them [70]. Persons on high-sodium diets show a significant increase in salt preferences as compared with persons on low-sodium diets [71]. On the other hand, the persons who limit salt intake for a longer period showed low salt taste preferences [72]. After 24 weeks of applying low-sodium diet the preferences for higher salt concentrations significantly decreased [73]. In a similar study, the reduction of sodium content in diet after 5 months resulted in reducing the preferred salt amount in soup and salted cookies [74].
The decreased salt preference observed can be explained by changing the sensitivity threshold to salt taste. This is an extremely important tip in hypertension prevention for all age groups, as in people suffering from hypertension, both in adults [75], and teenagers studies revealed [76] a significantly higher threshold of salt existence recognition than in healthy persons. That is why it is recommended to adapt to low salt food products, which results in accepting the products and introducing them to our everyday diet replacing products containing large amounts of salt.
Conclusions
1. One of the possibilities to effectively counteract hypertension epidemic is reducing salt intake, though the effect of such action would be considerably stronger if it was accompanied by the implementation of the National Hypertension Prevention Programme.
2. Spreading the knowledge concerning proper salt preferences even without the above-mentioned programme should result in a considerable reduction in salt intake.
*Financed KBN-S fund.
Piśmiennictwo
1. Roberts W. C.: High salt intake, its origins, its economic impact, and its effect on blood pressure. Am. J. Cardiol. 2001; 88(1): 1338-1346. 2.Lojewska A.: Sól i ... uczucia. Karczma Pol. 1995; 1: 22. 3.Ruusunen M., Puolanne E.: Reducing sodium intake from meat products. Meat Science 2005; 70(3): 531-541. 4.Drüeke T. B.: Roles of sodium and potassium in the development and management of hypertension. Nutr. Clin. Care 1999; 2(5): 292-299. 5.Kuhnlein H. V.: The trace element content of indigenous salts compared with commercially refined substitutes. Ecol. Food Nutr. 1980; 10(2): 113-121. 6.Sivakumar B., Brahmam G. N. V., Nair K. M. et al.: Prospects of fortification of salt with iron and iodine. Br. J. Nutr. 2001; 85 (Suppl 2): 167-173. 7.Esaiassen M., Ostli J., Joensen S. et al.: Brining of cod fillets: effects of phosphate, salt, glucose, ascorbate and starch on yield, sensory quality and consumers liking. Food Sci. Techn. 2005; 38(6): 641-649. 8.Piesiewicz H., Bartnikowska E.: Sól spożywcza we współczesnych technologiach piekarskich oraz aspekty żywieniowe. Przegl. Piek. Cuk. 2004; 52(3): 12-15. 9.Arakawa K.: What is the most important in treating hypertension? International Congress Series 2004; 1262: 593-596. 10.Elliott P., Stamler J., Nichols R. et al.: Intersalt revisited: further analyses of 24 hour sodium excretion and blood pressure within and across populations. Intersalt Cooperative Research Group. BMJ 1996; 312(7041): 1249-1253. 11.Johnson A. G., Nguyen T. V., Davis D.: Blood pressure is linked to salt intake and modulated by the angiotensinogen gene in normotensive and hypertensive elderly subjects. J. Hypertens. 2001; 19(6): 1053-1060. 12.Kromhout D.: Diet and cardiovascular diseases. J. Nutr. Health Aging 2001; 5(3): 144-149. 13. O´Shaughnessy K. M., Karet F. E.: Salt handling and hypertension. J. Clin. Invest. 2004; 113: 1075-1081. 14.Black H. R.: The burden of cardiovascular disease: following the link from hypertension to myocardial infarction and heart failure. Am. J. Hypertens. 2003; 16(9 Pt 2): 4-6. 15.García-Donaire J. A., Núňez A. G., Segura J., Ruilope L. M.: Cerebrovascular protection and antihypertensive therapy. Curr. Opin. Nephrol. Hypertens. 2004; 13(5): 507-512. 16.Rodgers A., Lawes C., MacMahon S.: Reducing the global burden of blood pressure-related cardiovascular disease. J. Hypertens. Suppl. 2000; 18(1): 3-6. 17.Frankel D. H.: Just a DASH of salt please. Lancet 2000; 355(9218): 1891. 18.Vollmer W. M., Sacks F. M., Ard J. et al.: Effects of diet and sodium intake on blood pressure: subgroup analysis of the DASH-Sodium Trial. Ann. Intern. Med. 2001; 135: 1019-1028. 19.Cook N. R., Kumanyika S. K., Cutler J. A.: Effect of change in sodium excretion on change in blood pressure corrected for measurement error. The Trials of Hypertension Prevention, Phase I. Am. J. Epidemiol. 1998; 148(5): 431-444. 20.Cutler J. A., Follmann D., Allender P. S.: Randomized trials of sodium reduction: an overview. Am. J. Clin. Nutr. 1997; 65(2 Suppl): 643-651. 21.Forrester T., Adeyemo A., Soarres-Wynter S. et al.: A randomized trial on sodium reduction in two developing countries. J. Hum. Hypertens. 2005; 19(1): 55-60. 22.He F. J., MacGregor G. A.: How far should salt intake be reduced? Hypertension 2003; 42(6): 1093-1099. 23.He F. J., Markandu N. D., MacGregor G. A.: Modest salt reduction lowers blood pressure in isolated systolic hypertension and combined hypertension. Hypertension 2005; 46(1): 66-70. 24.Law M.: Salt, blood pressure and cardiovascular diseases. J. Cardiovasc. Risk 2000; 7(1): 5-8. 25.Sacks F. M., Svetkey L. P., Vollmer W. M. et al.: Effects on blood pressure of reduced dietary sodium and the Dietary Approaches to Stop Hypertension (DASH) diet. N. Engl. J. Med. 2001; 344(1): 3-10. 26. Swift P. A., Markandu N. D., Sagnella G. A., He F. J., MacGregor G. A.: Modest salt reduction reduces blood pressure and urine protein excretion in black hypertensives: a randomized control trial. Hypertension 2005; 46(2): 308-312. 27. The Trials of Hypertension Prevention Collaborative Research Group. Effects of weight loss and sodium reduction intervention on blood pressure and hypertension incidence in overweight people with high-normal blood pressure. The Trials of Hypertension Prevention, phase II. Arch. Intern. Med. 1997; 157(6): 657-667. 28.Gomez G. B., Cappuccio F. P.: Dietary salt and disease prevention: a global perspective. Curr. Med. Chem. - Immun. Endoc. Metab. Agents 2005; 5: 13-20. 29.Collins R., Peto R., MacMahon S. et al.: Blood pressure, stroke, and coronary heart disease. Part 2, Short-term reductions in blood pressure: overview of randomised drug trials in their epidemiological context. Lancet 1990; 335(8693): 827-838. 30.McCarron D. A., Oparil S., Resnick L. M. et al.: Comprehensive nutrition plan improves cardiovascular risk factors in essential hypertension. Am. J. Hypertens. 1998; 11(1): 31-40. 31.Kuller L. H.: Salt and blood pressure. Population and individual perspectives. Am. J. Hypertens. 1997; 10: 29-36. 32.Selmer R. M., Kristiansen I. S., Haglerod A. et al.: Cost and health consequences of reducing the population intake of salt. J. Epidemiol. Community Health 2000; 54(9): 697-702. 33.Kunachowicz H., Nadolna I., Wojtasik A., Przygoda B.: Żywność wzbogacana a zdrowie. Instytut Żywności i Żywienia, Warszawa 2004. 34.Respondek W.: Zasady racjonalnego żywienia. W: Szponar L., Ciok J. (red.): Suplementacja a zdrowie człowieka. Instytut Żywności i Żywienia, Warszawa 2002; 31-37. 35.Chalcarz W., Spochacz-Przygocka E.: Ocena spożycia składników mineralnych przez pensjonariuszy z wielkopolskich domów pomocy społecznej. Nowiny Lekarskie 2005; 74(4): 369-372. 36. Consensus Action on Salt and Health: Action on Salt and Health. www.actiononsalt.org.uk, stan z dnia 21. 09. 2005. 37.Jeżewska-Zychowicz M.: Ocena zawartości wybranych składników mineralnych w całodziennych racjach pokarmowych młodzieży w wieku 13-15 lat. Żyw. Człow. Metab. 2005; 32, Supl. 1(1), 630-635. 38. Wajszczyk B., Charzewska J., Chabros E., Rogalska-Niedźwiedź M., Chwojnowska Z.: Zawartość wybranych składników mineralnych w dietach dziewcząt w wieku pokwitania a gęstość mineralna kości. Żyw. Człow. Metab. 2005; 32, Supl. 1(1): 122-128. 39.Bujko J., Myszkowska-Ryciak J., Nitka I.: Ocena spożycia składników mineralnych wśród studentów SGGW w Warszawie. Żyw. Człow. Metab. 2005; 32, Supl. 1(1): 655-659. 40.Czapska D., Ostrowska L., Stefańska E., Karczewski J.: Ocena zawartości wybranych składników mineralnych w całodziennej racji pokarmowej studentów uprawiających sport. Żyw. Człow. Metab. 2005; 32, Supl. 1(1): 668-672. 41.Bawa S., Kowaluk B., Wichrowska H.: Analiza spożycia wybranych składników mineralnych przez pacjentki z osteoporozą. Żyw. Człow. Metab. 2005; 32, Supl. 1(1): 169-176. 42.Dołowa J., Kałuża J., Roszkowski W., Brzozowska A.: Przeżywalność a realizacja norm i zaleceń żywieniowych u wybranej grupy osób starszych. Żyw. Człow. Metab. 2005; 32, Supl. 1(1): 753-758. 43.Ciok J.: Choroby na tle wadliwego żywienia. W: Szponar L., Ciok J. (red.): Suplementacja a zdrowie człowieka. Instytut Żywności i Żywienia, Warszawa 2002; 39-45. 44.Szostak W. B., Cybulska B.: Narodowy Program Profilaktyki Cholesterolowej w Polsce: dokonania i potrzeby przyszłości. Med. Metab. 1999; 3(2): 11-17. 45.Khan N. A., McAlister F. A., Lewanczuk R. Z. et al.: The 2005 Canadian Hypertension Education Program recommendations for the management of hypertension: part II - therapy. Can. J. Cardiol. 2005; 21(8): 657-672. 46.Girgis S., Neal B., Prescott J. et al.: A one-quarter reduction in the salt content of bread can be made without detection. Eur. J. Clin. Nutr. 2003; 57: 616-620. 47.Greenfield H., Smith A., Maples J., Wills R.: Contributions of foods to sodium in the Australian food supply. Hum. Nutr. Appl. Nutr. 1984; 38: 203-210. 48. Mattes R. D., Donnelly D.: Relative contributions of dietary sodium sources. J. Am. Coll. Nutr. 1991; 10(4): 383-393. 49.Shepherd R., Farleigh C. A.: Preferences, attitudes and personality as determinants of salt intake. Hum. Nutr. Appl. Nutr. 1986; 40(3): 195-208. 50.Coon K. A., Tucker K. L.: Television and children"s consumption patterns. A review of the literature. Minerva Pediatr. 2002; 54(5): 423-436. 51.Moya de Sifontes M. Z., Dehollain P. L.: Effect of mass communication media in food purchasing at the family level. Arch. Latinoam. Nutr. 1986; 36(1): 166-186. 52. Olivares S., Albala C., Garcia F., Jofre J.: Television publicity and food preferences of school age children of the metropolitan region. Rev. Med. Chil. 1999; 127(7): 791-799. 53.Rodgers A., Neal B.: Less salt does not necessarily mean less taste. Lancet 1999; 353(9161): 1332. 54. MacGregor G. A.: Salt - more adverse effects. Am. J. Hypertens. 1997; 10(5): 37-41. 55.Ball P., Woodward D., Beard T., Shoobridge A., Ferrier M.: Calcium diglutamate improves taste characteristics of lower-salt soup. Eur. J. Clin. Nutr. 2002; 56: 519-523. 56.Forte J. G., Miguel J. M., Miguel M. J., de Pádua F., Rose G.: Salt and blood pressure: a community trial. J. Hum. Hypertens. 1989; 3(3): 179-184. 57.Pekka P., Pirjo P., Ulla U.: Influencing public nutrition for non-communicable disease prevention: from community intervention to national programme - experiences from Finland. Public Health Nutr. 2002; 5(1A): 245-251. 58.Pietinen P., Lahti-Koski M., Vartiainen E., Puska P.: Nutrition and cardiovascular disease in Finland since the early 1970s: a success story. J. Nutr. Health Aging 2001; 5(3): 150-154. 59.Puska P.: Nutrition and mortality: the Finnish experience. Acta Cardiol. 2000; 55(4): 213-220. 60.van der Veen J. E., van Staveren W. A., van Dis S. J., de Graaf C.: Determinants of salt use in cooked meals in the Netherlands: attitudes and practices of food preparers. Eur. J. Clin. Nutr. 1999; 53(5): 383-394. 61.Glanz K., Basil M., Maibach E., Goldberg J., Snyder D.: Why Americans eat what they do: taste, nutrition, cost, convenience, and weight control concerns as influences on food consumption. J. Am. Diet. Assoc. 1998; 98(10): 1118-1126. 62. Koivisto U. K., Sjoden P. O.: Reasons for rejection of food items in Swedish families with children aged 2-17. Appetite 1996; 26(1): 89-103. 63.Krebs-Smith S. M., Heimendinger J., Patterson B. H., Subar A. F., Kessler R., Pivonka E.: Psychosocial factors associated with fruit and vegetable consumption. Am. J. Health Promot. 1995; 10(2): 98-104. 64.Kristal A. R., White E., Shattuck A. L. et al.: Long-term maintenance of a low-fat diet: Durability of fat-related dietary habits in the Women´s Health Trial. J. Am. Diet. Assoc. 1992; 92(5): 553-559. 65.Morreale A., Schwartz N.: Helping Americans eat right: Developing practical and actionable public nutrition education messages based on the ADA Survey of American Dietary Habits. J. Am. Diet. Assoc. 1995; 95(3): 305-308. 66.Crystal S. R., Bernstein I. L.: Infant salt preference and mother´s morning sickness. Appetite 1998; 30(3): 297-307. 67.Leshem M.: Salt preference in adolescence is predicted by common prenatal and infantile mineralofluid loss. Physiol. Behav. 1998; 63(4): 699-704. 68.Crystal S. R., Bernstein I. L.: Morning sickness: impact on offspring salt preference. Appetite 1995; 25(3): 231-240. 69.Stein L. J., Cowart B. J., Epstein A. N., Pilot L. J., Laskin C. R., Beauchamp G. K.: Increased liking for salty foods in adolescents exposed during infancy to a chloride-deficient feeding formula. Appetite 1996; 27(1): 65-77. 70.Beauchamp G. K., Engelman K.: High salt intake. Sensory and behavioral factors. Hypertension 1991; 17(1 Suppl): 176-181. 71.Teow B. H., di Nicolantonio R., Morgan T. O.: Sodium chloride preference and recognition threshold in normotensive subjects on high and low salt diet. Clin. Exp. Hypertens. 1985-86; 7(12): 1681-1695. 72.Yakura N., Minohara M., Sumida M.: A study on the relationship of taste-sensitivity to salt-restriction in adults. Nippon Koshu Eisei Zasshi 1990; 37(10): 867-872. 73.Blais C. A., Prineas R. J., Laing B., Ferrell M. F., Pangborn R. M., Borhani N. O.: Effect of dietary sodium restriction on taste responses to sodium chloride: a longitudinal study. Am. J. Clin. Nutr. 1986; 44(2): 232-243. 74.Bertino M., Beauchamp G. K., Engelman K.: Long-term reduction in dietary sodium alters the taste of salt. Am. J. Clin. Nutr. 1982; 36(6): 1134-1144. 75.Olayemi S. O., Mabadeje A. F.: Comparative study of salt taste threshold of hypertensives, their normotensive relatives and non-relatives. Niger. Postgrad. Med. J. 2003; 10(2): 96-98. 76.del Negro M. C., Oliver M., Arocha I., Arias F.: Arterial hypertension in the adolescent: its possible relation to the salt taste threshold. Rev. Esp. Cardiol. 1992; 45(4): 227-231.
