For thousands of years, the merits of salt were considered with high esteem. It made meals palatable and served as an efficient food preservative. It is only in the last hundred years that some medical scientists started to question the innocuity of usual salt intake. They held salt responsible for the induction of arterial hypertension and associated pathologies, and subsequently, for a number of other disease states. Those with the most profound conviction of its implication in health bondage called it the ‘poisonous gift of Neptune’. It is not our intention to enter the ongoing debate on what is the most appropriate intake of salt.
The relation between salt and sexuality is a matter for serious consideration, both with regard to an ancient myth related to Aphrodite and with regard to the association between salt appetite and reproduction. Restriction of salt intake has major effects on procreation, gestation and lactation. Salt-induced alterations of neurophysiological functions and sexual behaviour have already been presumed by the ancient Greeks. Later on, these assumptions received scientific support.
Mythology is a kind of counter-narrative description of what cannot be explained rationally as long as science prolegomena are not connected with human experience. Focussing on Aphrodite's myth, we shall try first to consider how salt, a mere mineral substance, is intimately related to the goddess of love in a recurrent struggle against sterility and death.
Aphrodite, who is she? What has she to do with salt?
Aphrodite is one of the major embodiments of the Great Goddess (Figure 1). The doublet sensuality–fertility is the force that features the source of life in her representation and helps generations to survive. The goddess, in the act of giving birth, transposes crude sexuality into creative energy. In the Aegean world, Aphrodite, goddess of love, prevents sterility and facilitates mating and procreation. For the ancient Greeks, the myth opens with Gaia and Uranos. Exhausted as she is with endless copulation, Gaia encourages Cronos to castrate Uranos.
Aphrodite in a very suggestive attitude.
Uranos (the Sky) came, bringing on night and longing for love, and he laid about Gaia (the Earth) spreading himself full upon her. Then the son (Cronos) from his ambush stretched forth his left hand and in his right took the great long sickle with jagged teeth, and swiftly lopped off his own father's members and cast them away… And white foam spread around them from the immortal flesh, and in it grew a maiden. First she drew near holy Kythera, and from there, afterwards, she came to sea-girt Kupros, and came forth an awful and lovely goddess … Gods and men call her Aphrodite and Aphrogenia (the foam-born) because she grew amid the foam. [1]
This is the most common version of the birth of Aphrodite, born in salty sea foam, i.e. the sperm bursting out of the castrated genitals of Uranos. Her birth is widely echoed by Greek writers. Its importance is attested by a number of surnames, including Haligeneous, ‘the salt-born’. This is the beginning of the story of salt and its generative power which Aphrodite symbolizes.
Since Antiquity, not only was food preservation widely based on salt, but salt was also present in remedies for impotence. The association with Aphrodite lends credence to this belief. Sacred prostitution and salt gathering represent two aspects of the Aphrodite myth, and although the latter is obfuscated by the former, it is presumably the most significant. Both are often intertwined.
Rituals and salt as a signifier
Myths are often intended to explain the universal beginnings, natural phenomena and anything else for which no simple explanation is available. Evaluating a myth without attentive contemplation of related rituals is an incomplete experience. Rituals are designed to replenish the initial power. Progressively, the ancient rituals and superposed poems failed to project men and women ‘into the divine realm, which had once seemed so close … As cities became better organised, policing more efficient … the gods seemed increasingly careless and indifferent to the plight of humanity’ [2].
Aphrodite personifies not only feminine beauty but also the origin of mankind from salted foam. Her myth is a structured system of signifiers. They constitute a set of cultural and technical vehicles that contribute to convey and protect basic information: crystallization of salt further to solar evaporation, generative power of salt and adverse effects of sodium deficiency. Dedicated rituals and sites participate in a process within which they mirror, for initiated eyes, a rea- lity that is not to be disclosed to those who look at.
Aphrodite is sometimes figured holding in her hand a little salt bag. It reminds of her birth in relation to the salt present in sea foam. Nowadays, light white salt that is generated when it begins to crystallize is called ‘αφρíνα’ (‘aphrina’) derived from ‘αφρóς’ (‘aphros’). It corresponds to the former ‘flos salis’ mentioned by Pliny the Elder. Bringing a salt bag is required to participate in Aphrodite festivals (Aphrodisia). These festivals were organized to vindicate the salt-born goddess and divine salt that is held to arouse sexual desire. More interestingly, salt participates in propitious action, an illustration of which is Odysseus spreading salt in ploughed sand when walking along the beach. Odysseus, feigning to sow salt is a stratagem to divert. ‘Sembrar la sal’ is still today an expression used for describing ancient practices in Central America, ‘brotando’ (germination) as well. Sharing salt when libations are taking place among partners is a well-established tradition.
From myth to science
There was no standard or fixed version of a myth. In the Homeric epic, Aphrodite is said to be the daughter of Zeus and Dione, but in the Theogony of Hesiod, she is described as having sprung from the salted foam of the sea. Most Greeks learnt their myth history from a rich and varied tradition, details being modified by poets, artists and philosophers.
Aristotle was basically collecting facts, anxious to state some points better than his predecessors about myths and the nature of things (saltiness of the sea and of certain continental springs, life's dependence on salt). Aristotle retained real interest in areas such as environment and health. He stated that sheep are in a better condition by keeping their hydro-mineral balance under control. The animals that drink saline water can copulate earlier. Salt must be given to them before they give birth and during lactation.
They give the flocks salt every five days in summer, to the extent of one medimnus (approx. 50 kg) to the hundred sheep, and this is found to render a flock healthier and fatter. In fact, they mixed salt with the greater part of their food. The admixture of salt in their food tends also to increase the quality of milk of the ewes. Should the ewes be fed with salted food as the lambing season draws near, they will get larger udders. [3]
This is proved to improve ‘ewes’ health at the lambing session. Later on, Pliny the Elder reflected the opinion of the Greek and Punic agronomists when writing Sheep, cattle, and draught animals are encouraged to pasture in particular by salt. Supply of milk is much more copious, and there is even a far more acceptable quality in the cheese’ [4].
One of the characters participating in Plutarch’ Symposiakon (Table Talks) draws his commensals’ attention to the fact that ‘Salt encourages remarkably generation’. Plutarch insisted on the generative power of salt by giving a few examples. Egyptian priests, who are professing chastity, were known to ‘avoid salt, as being by its heat, provocative and apt to raise lust’. ‘Those that breed dogs, when they find their bitches not prone to be hot, give them salt and seasoned flesh, to excite and arouse their sleeping lechery and vigour. Besides, the ships that carry salt breed a profusion of mice’. Females are quickly pregnant. ‘It is probable that salt rises an itching in animals, and so makes them salacious and eager to couple’ [5]. Such an allegation echoed Aristotle's History of animals. ‘Some people say, indeed stoutly maintain that, if they merely lick salt, mice become pregnant’ [6]. Even if the information fails to explain perfectly the phenomenon, its prescience predicts that salt intake has something to do with sexual maturity, desire, copulation, gestation periods and litter of rodents.
To date, it is acknowledged that salt restriction can weaken sexual desire, and some of the steroid and peptide hormones involved in reproduction generate salt appetite. Sodium intake rises under environmental stress conditions, in particular, in those who are not well adapted to withstand prolonged sodium shortage. Sodium deficiency is aggravated by other nutrient imbalances, more especially during reproduction cycles (mating, gestation and lactation).
Influence of salt intake and balanced diet on reproductive performance
The evolutionary emergence of salt appetite is possibly linked to the capacity of the brain to react to salt depletion by a specific drive for elective acquisition of salt. This drive is innate in animals. Several authors have stressed the difficulties that arthropods and herbivores face when trying to fulfil their need for sodium, which is in short supply in plants. Puddling behaviour is typically carried on by butterflies of the Lepidoptera order. Pola et al. [7] observed Papilio polytes drinking seawater at low tide to meet their salt requirements (Figure 2). Sodium intake by males affects their reproductive success, while the transfer of sodium to the female enhances reproductive propensity.
Specimen of Papilio polyteslicking seawater.
The literature provides information on the effects of an optimal-dietary electrolyte balance on reproductive performance and the physiological status of various mammal species. Factors affecting the fertility and reproduction performance of milking and gestating cows are numerous [8]. More than 50% of the variance in fertility is explained by nutritional factors including salt intake. A deficiency in sodium and associated excess of potassium can reduce fertility by irregular oestrus cycles, endometritis and follicular cysts (Table 1). Sodium supplementation via salt is very cheap and salt licks should be given ad libitum. Studies attest beneficial effects of dietary salt intake on the reproductive performance of sows [9]. Lowering sodium content resulted in a reduction of birth weight and, when continued for more than one reproductive cycle, in reduced litter size. The influence of dietary salt on water consumption, farrowing and reproductive performance of lactating sows was evaluated again in a more recent study by Seynave et al. [10]. They did not observe changes of the sows’ body weight or of litter size in response to a reduction in dietary salt intake. However, the average interval from weaning to oestrus was doubled and more sows failed to be successfully mated. This confirms observations regarding swine reported by Aristotle many centuries ago.
Influence of salt intake and balanced diet on reproductive performance
The evolutionary emergence of salt appetite is possibly linked to the capacity of the brain to react to salt depletion by a specific drive for elective acquisition of salt. This drive is innate in animals. Several authors have stressed the difficulties that arthropods and herbivores face when trying to fulfil their need for sodium, which is in short supply in plants. Puddling behaviour is typically carried on by butterflies of the Lepidoptera order. Pola et al. [7] observed Papilio polytes drinking seawater at low tide to meet their salt requirements (Figure 2). Sodium intake by males affects their reproductive success, while the transfer of sodium to the female enhances reproductive propensity.
Specimen of Papilio polyteslicking seawater.
The literature provides information on the effects of an optimal-dietary electrolyte balance on reproductive performance and the physiological status of various mammal species. Factors affecting the fertility and reproduction performance of milking and gestating cows are numerous [8]. More than 50% of the variance in fertility is explained by nutritional factors including salt intake. A deficiency in sodium and associated excess of potassium can reduce fertility by irregular oestrus cycles, endometritis and follicular cysts (Table 1). Sodium supplementation via salt is very cheap and salt licks should be given ad libitum. Studies attest beneficial effects of dietary salt intake on the reproductive performance of sows [9]. Lowering sodium content resulted in a reduction of birth weight and, when continued for more than one reproductive cycle, in reduced litter size. The influence of dietary salt on water consumption, farrowing and reproductive performance of lactating sows was evaluated again in a more recent study by Seynave et al. [10]. They did not observe changes of the sows’ body weight or of litter size in response to a reduction in dietary salt intake. However, the average interval from weaning to oestrus was doubled and more sows failed to be successfully mated. This confirms observations regarding swine reported by Aristotle many centuries ago.
Neuro-hormonal effects of salt restriction and possible consequences for sexual and reproductive activity
In rodents, an influence of salt intake on reproductive response was observed as well. Bird et al. [11] examined the relationship between maternal dietary salt intake during the period from conception through weaning and weanling rats’ elective consumption of salt. High maternal salt consumption stimulated offsprings’ salt intake. Observed group differences were not explained by changes in taste responsiveness. The authors of another study [12] reported an association between plasma oestradiol levels and salt intake in female rats, with higher intakes in hypertensive as compared to normotensive animals. They also observed an increase in salt consumption in response to large beta-oestradiol doses, in line with the contention that the adrenal glands play a role in salt appetite. The effects of sodium intake on reproductive performance were assessed [13] in four groups of BALB/C mice with ad libitum access to low or high sodium food. The daily sodium requirement for optimal reproduction was >400 μmol/day late in gestation and lactation. Sodium deficiency caused reproduction failure, primarily at the gestation step (Table 1).
Salt appetite and reproduction
The objective evaluation of salt appetite is not an easy task. Salt appetite is determined by highly intricate innate and acquired factors. Determining salt appetite is complicated in humans because of the absence of a generally accepted definition. Although preference for salt in a specific food can be modified by a learning process, it is basically innate. Salt intake is the result of the consumption of food containing sodium naturally and of food enriched in sodium chloride, with salt being added in industrial processing, cooking and/or on the table (discretionary salt). In animals, both spontaneous and need-induced salt intake are determined by a variety of physiological and genetic factors, which generate a specific appetite for salt. In many species, low-salt diets and depletion of body sodium stores stimulate salt appetite. Low salt intake blunts the response of the peripheral and central taste neurons to sapidity enforcing sodium. Thus rats ingest large amounts of salty food they otherwise would avoid [14].
Restriction of maternal salt intake during gestation has major effects on taste function and anatomy of the offspring. In addition to an increase in serum renin and aldosterone levels it results in a decrease in circulating insulin-like growth factor 1 (Table 1) that regulates amiloride-sensitive channel function in toad bladder epithelium [15]. Such alterations in physiological systems also have impact on amiloride-sensitive sodium channels in developing taste receptor cells. In rat offspring that are maintained on low-sodium chow throughout life, the chorda tympani nerve that innervates taste buds on the anterior tongue has reduced neurophysiological responses to sodium and altered morphology of its terminal field in the nucleus of the solitary tract, in contrast to the greater superficial petrosal nerve that innervates taste buds on the palate [16]. These differences led to the suggestion that a differential regulation of amiloride-sensitive sodium channels could be involved. Carvalho et al. [17] showed that salt satiety did not modify plasma atrial natriuretic peptide or vasopressin levels in pregnant rats despite their increased salt intake to meet greater sodium requirements during the reproduction cycle (Table 1).
In birds, like in rodents, sodium depletion increases plasma angiotensin and mineralocorticoid levels. High endogenous levels of these hormones may act in synergy to induce salt appetite [18].
Salt intake, sexual activity and the ‘chronic fatigue syndrome’
Scientists have described a huge number of traits in mammalian and avian species that evolved to attract mates and ensure reproduction [19]. Brain mechanisms that are involved in mate preference are largely unknown. Of interest, sexual attraction is associated with the dopaminergic reward system, and salt is implicated in the regulation of the dopaminergic system. Dopamine is important for motor functions and general arousal. It may have some relationship to mechanisms of ejaculation and neuroendocrine consequences of sexual activity or other processes associated with copulation [20] (Table 1). Several hypothalamic areas such as the medial preoptic area and the paraventricular nucleus are the source of pathways for reflexive move. Dopamine acting at the medial preoptic area level may regulate penile erection [21]. Erectile dysfunction has been a matter of concern through the ages [22], with beliefs and remedies including salt (Figure 3).
Women ‘salting’ their husbands to increase their libido [Engraving, 1557, Bibliothèque Nationale (Estampes), Paris].
Dopamine of renal origin has natriuretic and diuretic effects. Alvelos et al. [23] evaluated the effect of a low-sodium diet on the renal dopaminergic system in patients with heart failure. Sodium restriction led to an activation of antinatriuretic and antidiuretic systems. However, the renal ability to synthesize dopamine was increased, probably, as a counter-regulatory mechanism. Normally, a saline load increases renal dopamine production and natriuresis [24].
Steroid receptors such as progestin receptors can be activated after treatment with neurotransmitters like dopamine. A review by Auger [25] showed that some somasensory cues normally experienced by females—those associated with sexual intercourse—can activate progestin receptors to influence both neuronal response and oestrus behaviour.
Altered sexual function has long been known as a potential problem in the management of hypertension by salt restriction as illustrated by the Trial of Antihypertensive Interventions and Management (TAIM) [26]. Adding a low-sodium diet to either chlorthalidone or atenolol treatment did not improve blood pressure control. More disturbing, however, were more frequent complaints of fatigue and sexual impotence among patients assigned to severe sodium restriction (<70 mmol/day) [27].
Low salt intake has been incriminated in the pathogenesis of the ‘chronic fatigue syndrome’ (CFS), a disorder characterized by profound disabling fatigue, including sexual inactivity. Symptoms and signs include impaired concentration, attention or memory abilities and reduced libido and orthostatic hypotension (Table 1). Therapy consists in prescribing increased dietary salt or fludrocortisone to prevent abnormal reflex initiation. Holaigah et al. [28] recommended patients with CFS not to curtail their dietary salt intake, some of them being addicted to self-imposed sodium restriction.
Of related interest is a recent evaluation [29] of the effect of reduced salt intake on learning and memory capabilities in salt-sensitive (SS) Dahl rats—an animal model of salt-dependent hypertension. Salt restriction produced a significant decrement in selective cognitive functions, with marked alteration of social recognition memory and a radical impairment in the social transmission of food preference. Such findings put a cautionary note into the use of severe salt restriction.
Low salt intake in hunter–gatherer populations and salt wasting: implications for female fertility
Although sodium intake is fundamental for their survival, pre-agricultural societies differ in the access they have to salt and in their dedication to it. In many hunter–gatherer societies, food taboos dictate the diet of female individuals. These taboos are often to be respected throughout the most critical reproductive years of their life. Most of the food-related beliefs concern meat although salt, corn and fat are sometimes prohibited for ritual reasons. Australian aboriginal societies restrict food for pregnant and lactating women [30]. Aranda women cannot eat lizards until they have a child. Maternal malnutrition influences birth spacing and increases the risk of premature death (abortion) or low birth weight in neonates.
Ethnographic data on hunter–gatherer fertility indicate a low fertility rate in response to selective or incident malnutrition. A study related to its determinants in the Kung population [31] proposed an interaction of nutritional factors affecting ovulation, conception and parturition in aboriginal women of this stem. Other studies [32] have confirmed the role of severe deficiency states, including sodium and iodine deficiency, in low birth weight, impaired physical growth, mental retardation and poor school performance. Besides sodium, iodine needs [33] of women of childbearing age, pregnant and lactating women are scarcely covered by restrictive diets.
The Yanomamö Indians of Northern Brazil are thought to show no blood pressure increase with age in response to very low salt diet. Their demography [34] has been studied extensively. It was assumed that their reproductive performance would be a reasonable approximation of what is ignored, including salt in their diet. Of note, fertility is low, with an average of only one live birth every 4–6 years despite the continuous exposure to the risk of pregnancy. This is possibly in relation with lifelong low salt intake and corresponding hormonal adjustments including elevated serum renin and aldosterone levels. Oliver et al. [35] considered this as a standard condition for man during much of human evolution where free-need salt access was not possible.
Besides low salt intake in certain unacculturated populations, salt wasting deserves comment because it may contribute to a better understanding of the role of sodium deficiency in reduced fertility. The salt wasting syndrome [36] is a disorder of heterogeneous origin including congenital or acquired abnormalities of aldosterone synthesis or function. Congenital adrenal hyperplasia due to 21-hydroxylase deficiency is a salt wasting syndrome starting early in life. It is characterized by hyponatraemia and hyperkalaemia. In females it often leads to impairment of fertility, depending on the phenotype. Kochli et al. [37] recently investigated the relation of salt intake with salt wasting in such patients. Salt appetite correlated with symptoms of salt wasting, namely plasma renin activity, plasma potassium and urinary sodium. Plasma aldosterone did not correlate with sodium appetite nor did ACTH, which may raise salt appetite in animals. Sub-fertility is frequent in patients affected by this disease, as also discussed in another recent review [38] (Table 1).
Sodium and pregnancy
The possibility that oestrogens increase salt appetite in female animals may have important implications for women during pregnancy. Their increased sodium appetite probably reflects adaptative mechanisms and needs. Pregnancy implies a challenge to sodium homeostasis, leading to a natural increase in the search for more salt. Lactating rats markedly increased their intake of sodium chloride after having been deprived of salt for 4 days, whereas virgin female rats did not [39]. The observed increase in salt intake is also a response to enhanced metabolic demands of the growing foetus during pregnancy and of the newborn during lactation. Of interest, there also is a sexual dimorphism in salt appetite. Thus adult male rats drank significantly more 3% saline than female rats after severe sodium restriction for 8 days [40]. After gonadectomy, however, male and female rats drank comparable amounts of saline. This sexually dimorphic phenomenon [41] could be governed by the sex hormones testosterone and oestrogen.
In pregnant women, in the presence of normal salt intake, plasma renin activity and angiotensin II and aldosterone levels increase gradually by the eighth week of normal pregnancy until parturition (Table 1). In contrast, in the condition of pre-eclampsia there is no systemic activation of the renin–angiotensin system but instead local activation in the decidua and increased vascular sensitivity to angiotensin II, together with pathologic changes in the activity of vascular endothelial growth factor and its receptors, antagonists and reduced placental growth factor [42]. The role of sodium in the pathogenesis and/or severity of pre-eclampsia is the subject of longstanding discussion. There appears to be a reasonable degree of agreement that salt intake should not be reduced during pregnancy. In pregnant rats a 0.9% salt supplement prevented the usual pregnancy-associated decrease in blood pressure, together with a noticeable inhibition of renin–angiotensin system activity [43].
Some 50 years ago, Robinson [44] investigated the impact of a high- versus low-salt diet in the early period of pregnancy in a large cohort of women. He found a lower incidence of oedema, toxaemia and bleeding during pregnancy and of perinatal death in those with high salt intake. Giardina et al. [45] examined the impact of a low-salt diet on arterial function in pregnancy. They observed an increase in vascular reactivity that adds to the concern about adverse effects of sodium restriction. Therefore, any reduction of salt consumption during pregnancy should be carefully monitored, especially with respect to the potential risk of aggravating pregnancy-induced hypertension.
In pregnant women there is thus no evidence of benefit from reduced salt intake. A recent Cochrane review by Duley et al. [46] assessed the effects of changes in dietary salt intake during pregnancy on the risk of developing pre-eclampsia and its complications. The authors concluded that salt consumption should remain a matter of personal preference. This recommendation is also important for guaranteeing a sufficient iodine intake together with discretionary salt provided that it is duly iodized.
Early postnatal development
Sodium appears to be of major importance in early development throughout the animal kingdom, from butterflies to mammals, and in man as well. Early sodium deprivation can provoke salt appetite in adulthood. Chevalier [47] reviewed the evidence for the necessity of a balanced sodium intake and the detrimental effect of its deficiency or its restriction in early postnatal development. He focused on renal sodium conservation at this time period because it is decisive for subsequent maturation. Regardless of sodium supplementation, human neonates show a negative sodium balance for the first 4 days of life, and then shift to a positive sodium balance, with a marked increase in plasma renin activity and aldosterone levels during the first 3 weeks of life. Another study [48] identified a robust inverse correlation between the lowest serum concentration during the neonatal period of low birth weight children and reported dietary sodium intake in adolescence. This would indicate that very low circulating sodium concentrations in neonates induce a permanent increase in salt appetite later in life (Table 1).
The importance of low birth weight in the aetiology of coronary artery disease or type 2 diabetes was reviewed in relation to an inadequate foetal nutrient supply by Byrne et al. [49]. These authors attempted to better understand cellular and molecular mechanisms that might explain the association between low birth weight and adult disease risks. Insulin has a central role in foetal growth in relation to maternal malnutrition. Insulin resistance induced by low sodium intake might have an adverse influence on development. Information on nutrient interactions is an important area that has emerged recently, aimed at correcting mineral deficiencies and improving cardiovascular outcomes. Manipulations of the diet can alter or restore functions on which the foetus depends during pregnancy.
Vidonho et al. [50] performed a study in pregnant Wistar rats, examining the effect of perinatal reduction of salt intake on blood pressure and carbohydrate and lipid metabolism in adult offspring of dams fed either on high-salt, normal-salt or low-salt diet during pregnancy and lactation. After weaning, the offspring received only normal-salt diet. They observed a significant association between salt restriction, low birth weight and insulin resistance in the offspring (Table 1). Their findings suggest that low-salt diet during pregnancy and lactation exerts negative influences on foetal development and may be responsible for diseases in adult life through long-term effects on arterial pressure, insulin sensitivity and plasma lipids. To evaluate the consequences of dietary salt consumption during the perinatal period further, the same Brazilian group [51] reinvestigated variations in sodium intake in Wistar rats comparing the effects of chronic sodium overload with those of chronic sodium restriction during pregnancy and lactation. They found that when the male offspring of dams fed with a low-salt diet during pregnancy and lactation reached adulthood, they disturbingly developed a higher body weight, with an increase in brown adipose tissue angiotensin II content, but a decrease in white adipose tissue angiotensin II content, and a decrease in uncoupling protein 1 expression and energy expenditure. They concluded that perinatal deviations of salt intake towards either sodium excess or sodium deficiency lead to abnormal changes in body weight, food intake, energy expenditure, hormonal profile and tissue angiotensin II content.
Conclusion
Dietary salt restriction has major effects on procreation, gestation and lactation. Diet-induced alterations of neurophysiological mechanisms have already been presumed by the ancient Greeks. In the last decades, our understanding of the underlying mechanisms has greatly improved. Several steroid and peptide hormones involved in reproduction appear to induce salt appetite. Sodium intake rises in response to environmental stress conditions, particularly, in individuals not well adapted to withstand prolonged sodium shortage. Sodium deficiency is aggravated by other nutrient imbalances. Recent literature provides ample information on the effects of an optimal dietary electrolyte balance on reproductive performance and the physiological status of various species. An objective evaluation of salt appetite in humans is often obfuscated by present misconceptions of the salt and health issue. The study of the physiological mechanisms leading to high salt intake preference irrespective of a possible impact on extracellular volume and blood pressure is deviated towards the hypertension issue and the constant advice to restrict salt consumption in the population at large, irrespective of possible adverse effects of a low-sodium diet. Altered sexual function has long been known as a potential problem linked to severe reductions of salt intake in the management of hypertension. The fact that there are still hunting–gathering individuals around, who survive on very low-salt diets is used to recommend salt restriction for general population, although these individuals do not reproduce well and most of them die early in life. When considering optimal salt intake, let us not forget about the powerful effects of salty sea foam on procreation and the generative, aphrodisiac power attributed to salt in ancient Greek mythology, and let us remind the major contribution of a sodium replete state to fertility and reproductive performance.
Conflict of interest statement. B. Moinier declares receiving consulting fees from the Comité des Salines de France; T. Drüeke, consulting fees and grant support from the Comité des Salines de France.
(See related article by S. Shaldon and J. Vienken. The long forgotten salt factor and the benefits of using a 5-g-salt-restricted diet in all ESRD patients.Nephrol Dial Transplant 2008; 23: 2118–2120.)
(See related article by D. A. McCarron. Dietary sodium and cardiovascular and renal disease risk factors: dark horse or phantom entry? Nephrol Dial Transplant2008; 23: 2133–2137.)
(See related article by A. Mimran and G. du Cailar. Dietary sodium: the dark horse amongst cardiovascular and renal risk factors. Nephrol Dial Transplant2008; 23: 2138–2141.)
- © The Author [2008]. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.For Permissions, please e-mail:journals.permissions@oxfordjournals.org
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