It's Time to End the War on Salt

Source: http://www.scientificamerican.com/article.cfm?id=its-time-to-end-the-war-on-salt

The zealous drive by politicians to limit our salt intake has little basis in science

By Melinda Wenner Moyer | July 8, 2011 |26

For decades, policy makers have tried and failed to get Americans to eat less salt. In April 2010 the Institute of Medicine urged the U.S. Food and Drug Administration to regulate the amount of salt that food manufacturers put into products; New York City Mayor Michael Bloomberg has already convinced 16 companies to do so voluntarily. But if the U.S. does conquer salt, what will we gain? Bland french fries, for sure. But a healthy nation? Not necessarily.

This week a meta-analysis of seven studies involving a total of 6,250 subjects in the American Journal of Hypertension found no strong evidence that cutting salt intake reduces the risk for heart attacks, strokes or death in people with normal or high blood pressure. In May European researchers publishing in the Journal of the American Medical Association reported that the less sodium that study subjects excreted in their urine—an excellent measure of prior consumption—the greater their risk was of dying from heart disease. These findings call into question the common wisdom that excess salt is bad for you, but the evidence linking salt to heart disease has always been tenuous.

Fears over salt first surfaced more than a century ago. In 1904 French doctors reported that six of their subjects who had high blood pressure—a known risk factor for heart disease—were salt fiends. Worries escalated in the 1970s when Brookhaven National Laboratory's Lewis Dahl claimed that he had "unequivocal" evidence that salt causes hypertension: he induced high blood pressure in rats by feeding them the human equivalent of 500 grams of sodium a day. (Today the average American consumes 3.4 grams of sodium, or 8.5 grams of salt, a day.)

Dahl also discovered population trends that continue to be cited as strong evidence of a link between salt intake and high blood pressure. People living in countries with a high salt consumption—such as Japan—also tend to have high blood pressure and more strokes. But as a paper pointed out several years later in the American Journal of Hypertension, scientists had little luck finding such associations when they compared sodium intakes within populations, which suggested that genetics or other cultural factors might be the culprit. Nevertheless, in 1977 the U.S. Senate’s Select Committee on Nutrition and Human Needs released a report recommending that Americans cut their salt intake by 50 to 85 percent, based largely on Dahl's work.

Scientific tools have become much more precise since then, but the correlation between salt intake and poor health has remained tenuous. Intersalt, a large study published in 1988, compared sodium intake with blood pressure in subjects from 52 international research centers and found no relationship between sodium intake and the prevalence of hypertension. In fact, the population that ate the most salt, about 14 grams a day, had a lower median blood pressure than the population that ate the least, about 7.2 grams a day. In 2004 the Cochrane Collaboration, an international, independent, not-for-profit health care research organization funded in part by the U.S. Department of Health and Human Services, published a review of 11 salt-reduction trials. Over the long-term, low-salt diets, compared to normal diets, decreased systolic blood pressure (the top number in the blood pressure ratio) in healthy people by 1.1 millimeters of mercury (mmHg) and diastolic blood pressure (the bottom number) by 0.6 mmHg. That is like going from 120/80 to 119/79. The review concluded that "intensive interventions, unsuited to primary care or population prevention programs, provide only minimal reductions in blood pressure during long-term trials." A 2003 Cochrane review of 57 shorter-term trials similarly concluded that "there is little evidence for long-term benefit from reducing salt intake."

Studies that have explored the direct relationship between salt and heart disease have not fared much better. Among them, a 2006 American Journal of Medicine study compared the reported daily sodium intakes of 78 million Americans to their risk of dying from heart disease over the course of 14 years. It found that the more sodium people ate, the less likely they were to die from heart disease. And a 2007 study published in the European Journal of Epidemiology followed 1,500 older people for five years and found no association between urinary sodium levels and the risk of coronary vascular disease or death. For every study that suggests that salt is unhealthy, another does not.

Part of the problem is that individuals vary in how they respond to salt. "It's tough to nail these associations," admits Lawrence Appel, an epidemiologist at Johns Hopkins University and the chair of the salt committee for the 2010 Dietary Guidelines for Americans. One oft-cited 1987 study published in the Journal of Chronic Diseases reported that the number of people who experience drops in blood pressure after eating high-salt diets almost equals the number who experience blood pressure spikes; many stay exactly the same. That is because "the human kidney is made, by design, to vary the accretion of salt based on the amount you take in," explains Michael Alderman, an epidemiologist at the Albert Einstein College of Medicine and former president of the International Society of Hypertension.

Some physicians argue that although tiny blood pressure drops will not have a big effect on individuals—they will not really affect your risk of having a heart attack—they may end up saving lives at the population level, in part because a small percentage of the population, including some African-Americans and elderly individuals, seem to be hypersensitive to salt. For instance, a study published in February 2010 in the New England Journal of Medicine estimated that cutting salt intake by about 35 percent would save at least 44,000 American lives per year. But such estimates are not evidence, either; they are conjecture. And low-salt diets could have side effects: when salt intake is cut, the body responds by releasing renin and aldosterone, an enzyme and a hormone, respectively, that increase blood pressure.

Rather than create drastic salt policies based on conflicting data, Alderman and his colleague Hillel Cohen propose that the government sponsor a large, controlled clinical trial to see what happens to people who follow low-salt diets over time. Appel responds that such a trial "cannot and will not be done," in part because it would be so expensive. But unless we have clear data, evangelical antisalt campaigns are not just based on shaky science; they are ultimately unfair. "A great number of promises are being made to the public with regard to this enormous benefit and lives saved," Cohen says. But it is "based on wild extrapolations."

Sex Facts

During the months of research which have gone into devising our sexual compatibility test, we’ve uncovered some pretty extraordinary facts. We reckon they’re too cool to keep to ourselves.
1. A woman is more likely to want to commit adultery during ovulation than at any other time in her cycle.
2. Telling a convincing lie to someone is much more difficult when you find them sexually attractive.
3. Minute quantities of over 30 elements have been identified in human semen. These include nitrogen, fructose, lactic acid, ascorbic acid, inositol, cholesterol, glutathione, creatine, pyruvic acid, citric acid, sorbitol, urea, uric acid and Vitamin B12, along with various salts and enzymes.
4. Chocolate contains phenylethylamine, the same feel-good chemical responsible for the ecstatic high people experience through sexual attraction and love.
5. Women who have given birth have darker labia minora than women who haven’t.
6. The majority of women experience a peak in libido just before their period.
7. -321°F is the temperature at which sperm banks store donor semen. At this temperature, semen can be stored indefinitely.
8. The point at which the average man reaches his sexual peak is between the ages of 17 and 18.
9. The earth could be re-populated to its current level using the number of sperm that could fit into an aspirin capsule.
10. A chicken egg could accommodate the number of female ova necessary to repopulate the earth to its present numbers.
11. During sexual intercourse, in addition to the genitals and breasts, the inner nose also swells.
12. White women are the most likely to engage in anal sex, particularly if they also have a college degree.
13. During erection, a smaller flaccid penis tends to have a greater percentage increase than a larger flaccid penis.
14. A teaspoon of semen contains approximately 5 calories.
15. Sex burns off an average of about 100 calories per session.
16. On average, from two to five million sperm are released each time a man ejaculates.
17. During any given period, women who read romance novels have a tendency to have twice as many lovers as those who don’t.
18. Almost a third of all women over 80 years of age still have sex with their spouse or boyfriend.
19. For both men and women, the heart rate averages 140 beats per minute at the point of orgasm.
20. The average woman will have sex more than 3,000 times over the course of her reproductive years.
21. Most men under 40 years of age can achieve an erection in less than 10 seconds.
22. Heterosexual anal sex is something 43% of women have experienced.
23. Women consider penis size the ninth most important feature for a man, while men rate it much more highly, in third place.
24. When a man ejaculates, the initial spurt travels at 28 miles per hour – faster than the world record for the 100m sprint, which currently stands at 22.9 miles per hour.
25. In one hour, the average sperm can swim seven inches.
26. With nothing in its path, a penis can shoot semen anywhere from 12 to 24 inches.
27. The longest erect penis on record was 13 inches. The smallest was 1cm.
28. There are 20 male masochists for every female masochist.
29. The average adult testicle contains enough sperm to measure a quarter of a mile laid out end to end.
30. For 75% of men, ejaculation occurs within 3 minutes of penetration.
31. During an average man’s lifetime, he will ejaculate approximately 17 litres of semen, which amounts to about half a trillion sperm.
32. The testes increase in size by 50% when a man is sexually aroused.
33. Australians are the most receptive to the idea of having a threesome – 28% of them claim to have tried it.
34. 1 in 50 people claim to have had sex in an aeroplane.
35. 15% of adults have had sexual intercourse at work.
36. 41% of men would like to have sex more frequently. Only 29% of women share this urge.
37. Greek couples have sex an average of 138 times a year – placing them at the top of the world sex league. Japanese couples have sex just 45 times a year, which puts them in last place.
38. 5% of adults have sex once a day. 20% have sex 3 – 4 times per week.
39. Every time they engage in oral sex with their partner, 30% of women swallow.
40. When sexually aroused, 60% of men get erect nipples.
41. Half of single women have sex by the third date.
42. 80% of men living in the USA have been circumcised.
43. Women over 40 years of age are more likely to masturbate than any other group.
44. There’s a direct link between how often a man has sex and his life expectancy.
45. According to experts, sex is about 10 times more effective as a tranquilliser than Valium.
46. Sex can relieve a headache – it releases the tension, which restricts blood vessels in the brain.
47. 44% of women find it impossible to enjoy sex with a man who is not their intellectual equal. Just 31% of men share this problem.
48. There are about 1,000 recognised euphemisms for ‘vagina’ in the English language.
49. At any given time, 25% of people are daydreaming about sex.
50. Over half of American adults have used the phone, email or text message to have sex.
51. According to studies, the larger a man’s testicles, the more likely he is to stray.
52. 75% of Japanese women own a vibrator. The average worldwide is 47%.
53. It takes two tablespoons of blood to get the average man’s penis erect.
54. During their lifetime, the average driver will have sex in their car six times.
55. Americans spend twice as much money on pornography as they do on biscuits.
56. The clitoris contains twice as many nerve fibres as the penis – a toe-curling 8,000.
57. One in five women living with their boyfriend has more than one sexual partner.
58. Besides humans, bonobos (a type of chimp) and dolphins are the only animals that have sex for pleasure.
59. It tends to be easier for women to orgasm during ovulation than at any other time in their cycle.
60. The size of the vagina decreases by 30% as orgasm becomes imminent.
61. While giving birth, some women have been known to experience orgasm.
62. Inside the female body, sperm cells can survive for up to nine days.
63. For up to 70% of women, simultaneous direct stimulation of the clitoris during intercourse is essential for them to reach orgasm.
64. Over 30% of men suffer from premature ejaculation. 10% of men are affected by erectile dysfunction.
65. It’s possible to relieve depression through masturbation.
66. The longer a man’s ring finger is compared to his index finger, the more testosterone he has.
67. The average aroused vagina is 4 inches long – shorter than the average erect penis, which measures in at 6 inches.
68. The average woman can reach orgasm in about 4 minutes through masturbation, while through intercourse, it can take 10 – 20 minutes.
69. Sneezes, along with orgasms, are the only physiological responses that cannot be voluntarily stopped once they have started.
70. Straight men tend to have smaller penises than gay men.
71. 85% of women are very satisfied with their partner’s penis size.
72. Evidence exists indicating that penis size may be linked to index finger length.
73. In rare cases, menstrual cramps have been known to bring about orgasm.
74. The amount of wet dreams a man is likely to have increases in line with the number of years spent in formal education.
75. Compared to anywhere else, adults are more likely to tell a lie in bed.
76. The majority of women prefer to have sex in the dark.
77. Men find women with enlarged pupils more sexually attractive.
78. When having sex, black women are 50% more likely to reach orgasm than white women.
79. 60% of non-smoking women have had no sexual partners in the past year, while 70% of women who smoke have had more than four lovers over the same timescale.
80. Women who are prone to migraines tend to have a higher sex drive than those who are not.
81. Thirty four per cent of men have told lies in order to have sex. Ten per cent of women have done the same.
82. More than 50% of all cheating wives choose married men as their lovers.
83. About 1% of women can achieve orgasm solely through breast stimulation.
84. Within the week, 22% of women tell at least five friends about their first sexual experience with a partner.
85. 70% of men and women admit to having fantasised about someone else while having sex.
86. Two thirds of runners admit to having thought about sex while running.
87. 68% of men and 59% of women had a sexual liaison with someone in their past, which they have not told their current partner about.

About | Amazing Facts | Privacy | Contact
© Lustability 2011