Salt

Salt is probably the single most unhealthy element in the human diet.  Sodium intake should be at most half (1150mg/day) of the maximum the U.S. government recommends (2500mg/day) and one-quarter as much as most people consume.  Only 225-500 mg/d is needed for health since the body is extremely good at conserve sodium if levels get low.  It is almost impossible to get too little sodium in the diet because many foods have some sodium in them naturally (diary, meat, many vegetables).  The only natural case of low sodium I have heard recently was a marathon runner consuming huge quantities of plain water, while thousands of dying of too much salt every month.  

The best policies are no salt shaker, no added salt in the cooking, no ham or lunch meats, and home-made soup instead of canned soup.  Indeed, most canned and processed foods are high in salt.  Look at the label.  If the milligrams of sodium (mg.) is higher than the calories, the food is a high salt food.  If it is more than double the number of calories, you should really look hard to find out if you can't find a substitute. Oddly, bread is a major source of sodium accounting for 15%. Store bought crackers and mixes are often high in salt.  Recipes turn out fine when the salt is simply left out.  "No Salt" potassium chloride is an excellent salt substitute.

Salt causes the large majority of high blood pressure, although obesity is another significant factor.  An incredible 90% of us will develop high blood pressure before we die.  Half of all high blood pressure is untreated and half of the others are inadequately treated.  High blood pressure is a major cause of the #1 and #3 causes of death in America, i.e., heart disease and stroke, as well being a cause of osteoporosis, kidney stones, kidney disease, stomach cancer, and gastric ulcers.  Salt also appears to exacerbate asthma, at least somewhat, especially exercise-induced asthma.  Some research even suggests salt increases the chance of developing cataracts. and fibromyalgia.

Low Salt, Low Meat for Kidney Stones: A random assignment study of kidney stone sufferers found 20% on low salt/meat diet had recurrence in 5 yr vs. 38% on low calcium diet. U Parma. NEJM 1/10/02. 10% US get stones with 80% being men. 15% of cases need surgery or shockwave. Salt has been found to increase stones.

Low Salt Vegan Diet Helps Fibromyalgia: 18 patients shifted to low salt, uncooked vegan diet and 15 stayed omnivorous. Urine sodium dropped 2/3s. Pain, joint stiffness, sleep quality improved dramatically. Cholesterol and weight also showed sizable decreases. Scand J Rheumatol 2000;29(5):308-13

BP Not Improving: Framingham study found an increase of BP from 30 years of age to 65 years of age of 20 mm Hg systolic and 10 mmHg diastolic the norm. Nationally, no improvement over last 40 years despite improved detection and Rx. Author says need weight loss, decreased salt, and decreased alcohol consumption. JAMA ’96;275:1571. Nationally, weight has increased considerably over the last 40 years.

HBP up 100% in 6 Years in Phillipines; No Salt, No HBP; Don't Feed Your Baby Salty Food: In 1992, 11% had high blood pressure; now 22% do. HBP is highest in Mindanao where salty preserved fish, shrimps, and sauces are popular. Fatty salty fast foods also held a factor although there is no research. Some still undeveloped countries have HBP rates as low as 7% v. US 26%. Lancet 8/22/98. BP is not increased by nonchloride salts of sodium. The author notes the INTERSALT study (Br Med J ’88 297:319-28) where there was very little HBP in four populations who had no salt intake. A randomized Dutch study of infants fed low salt for first 6 months found lower BP with a difference still found after 10 yr. Ed: While I haven't read it, I strongly suspect that the salt level of breast milk is strongly dependent on the salt intake of the mother.  A very low salt diet is best.

Avoiding Salt Avoids Heart Attacks: An Australian study found relative risk for non-vigorous exercise was 0.5 and for avoiding added salt 0.6. in a case-control study of 336 AMI and 735 controls. Int J Epidemiol 1999 Oct;28(5):846-52

Salt Harmful for Obese in NHANES: 9400 obese and non-obese found high sodium intake is strongly and independently associated with an increased risk of cardiovascular disease and all-cause mortality in overweight persons but not for non-obese. JAMA 1999 Dec 1;282(21):2027-34; Data from 11,346 NHANES adults shows sodium intake was inversely associated with all-cause (p=0.0069) and cardiovascular disease (CVD) mortality (p=0.086). Surprisingly, total calorie intake was also inversely linked to mortality (25.03 to 18.40, p<0.0001). Finally, the sodium/calorie ratio was directly associated with all-cause (p=0.0004) and CVD mortality (p=0.0056). By contrast, calorie intake in the presence of the two measures of sodium intake was not independently associated with mortality. Lancet 1998 Mar 14;351(9105):781-5; Lancet. 1998 Sep 19;352(9132):987-8; Lancet. 1998 May 16;351; favoring restriction = Med J Aust. 1999 Feb 15;170(4):176-8. (Ed: These slightly odd findings still support avoiding salt. Perhaps the reason people who ate more lived longer was that they were exercising more and therefore healthier.)

Potassium Found Highly Protective in Scottish: 11,300 followed for 8 years. Smoking, HBP (especially systolic), and fibrinogen found to be other important risk factors for mortality. Potassium measured in urine strongly protective. Inactivity, both leisure and at work, were associated with higher mortality. Modest alcohol intake was protective against heart disease. Height was protective. Weight, like alcohol, showed a U-shaped mortality curve. Lower salt excretion and early menopause very weakly associated with higher mortality. Oddly, uric acid (very high not good), energy intake all not significant. Vitamins C, E, and carotenoids were a little protective. BMJ 1997;315:722-729 (20 September)

Review of Controlled Studies Reducing Salt Lower BP: Author reviews 11 studies of over 6 months duration and finds slight decrease in BP (1.1 mm Hg systolic), but that the studies had few deaths or cardiovascular events and no conclusions on benefit are possible. BMJ 2002;325:628 ( 21 September ). Ed: The harm of salt accumulates very slowly.  Epidemiologic studies show that the harm is probably less than 1.0 mm Hg per year, but the damage accumulates year after year after year.

Diet Factors for Cataracts: Bad = Butter, Fat, Salt, Good = Spinach, Tomatoes, Cruciferae, Citrus: Alcohol, coffee, decaffeinated coffee, tea, and cola intakes were not associated with cataract extraction. Among food items, reduced ORs for cataract extraction (highest tertile of intake compared to the lowest), with a significant inverse trend in risk, were found for intake of meat (OR 0.6, 95% CI 0.4 to 0.9), cheese (OR 0.7, 95% CI 0.5 to 1.0), cruciferae (OR 0.5, 95% CI 0.3 to 0.8), spinach (OR 0.6, 95% CI 0.4 to 0.9), tomatoes (OR 0.5, 95% CI 0.4 to 0.8), peppers (OR 0.7, 95% CI 0.4 to 1.1), citrus fruit (OR 0.5, 95% CI 0.2 to 1.3), and melon (OR 0.5, 95% CI 0.4 to 0.8). A significant increase in risk was found for the highest intake of butter (OR 2.8, 95% CI 1.2 to 6.4), total fat (OR 1.8, 95% CI 1.2 to 2.8), and salt (OR 2.4, 95% CI 1.4 to 4.0) compared to the lowest, and for consumption of oil other than olive oil (OR 1.6, 95% CI 1.1 to 2.2). Among micronutrients, lower ORs for cataract extraction (highest quintile of intake compared to the lowest) were found for intake of calcium (OR 0.5, 95% CI 0.3 to 0.8), folic acid (OR 0.4, 95% CI 0.2 to 0.7), and vitamin E (OR 0.5). 207 cases. 600 controls. Ann Epidemiol 1996 Jan;6(1):41-6

Potassium Helps Some of Those Not Restricting Sodium: JAMA 5/28/97 277:1624 Whelton. Reviewed 33 DB PC trials of 2609 patients given potassium supplements.  Potassium decreased systolic pressure 3.11 mmHg and diastolic 1.97mmHg. Helps those with high sodium intake especially. Supplements did not help with normal blood pressure.  A biased health food store magazine Energy Times misrepresented a study from the journal Hypertension (’98;31:131-8) claiming that it found potassium supplements lowering BP for 300 women. But the actual article found potassium supplements helped only those with low intakes and that Ca++ and Mg++ supplements were not of benefit despite low intake, a fact left out by Energy Times.  Fruits, nuts, beans, cereals, and dairy are all high in potassium.

AHA On Salt: The AHA Nutrition Committee announced that there is no evidence that "limiting NaCl consumption to 6 g per day poses any health risk (Circ 98 98:613-17. A reduction of 2 mm Hg diastolic results in 15% decrease in stroke risk and 6% decrease in CHD risk. Chimp studies show adding 5g/d to usual low salt, high K diet increases BP dramatically. Two meta-analyses of 32 and 52 studies both found reducing salt reduces HBP. Two meta-analyses found adding K supplements of 60-120 Meq/day lowers BP. Low calcium intake (300-600mg/d) was associated with HBP but it is unclear if any diff at higher levels. Potassium and calcium help offset high salt intake especially in hypertensives. Calcium does not prevent preeclampsia. Magnesium supplementation has not been found of benefit.

Salt VIP: The rise in average blood pressure with age seen in Western populations does not occur in isolated traditional nomadic communities. Several factors contribute to the higher blood pressure in the West. Salt is particularly important, however, because its effect on blood pressure is large, the dietary intake by Western populations is high and a large reduction in its intake is realistic. The size of the relationship between salt and blood pressure depends on age and, in trials, the duration of reduction of intake of salt. Results of many of the randomized trials have suggested that reduction of dietary salt exerts only a small effect on average blood pressure; this is because their subjects have been young (average age 26 years) and trials have been of short duration (average 2 weeks). Analysis of observational data concerning various communities indicated that a reduction in dietary intake of sodium of 100 mmol/24 h (3 g of salt, a good reduction) lowers systolic blood pressure in subjects aged 50-65 years by 10 mmHg on average. Much evidence corroborates this estimate, including data from the Intersalt study and a randomized controlled trial of reduction of intake of salt by older persons. This reduction in blood pressure would reduce age-specific stroke mortality by an estimated 22% and mortality from heart disease by 16%. Reducing the amount of salt added to manufactured foods is an important public-health target. J Cardiovasc Risk 2000 Feb;7(1):5-8

Salt Restriction & Wt Loss Work Trials of Hypertension Prevention, phase 1, in Baltimore, Md. At baseline (1987 to 1988), subjects were 30 to 54 years old and had a diastolic blood pressure (BP) of 80 to 89 mm Hg and systolic BP <160 mm Hg. They were randomly assigned to one of two 18-month lifestyle modification interventions aimed at either weight loss or dietary sodium reduction or to a usual care control group. At the posttrial follow-up (1994 to 1995), BP was measured by blinded observers who used a random-zero sphygmomanometer. Incident hypertension was defined as systolic BP > or =160 mm Hg and/or diastolic BP > or =90 mm Hg and/or treatment with antihypertensive medication during follow-up. Body weight and urinary sodium were not significantly different among the groups at the posttrial follow-up. After 7 years of follow-up, the incidence of hypertension was 18.9% in the weight loss group and 40.5% in its control group and 22.4% in the sodium reduction group and 32.9% in its control group. In logistic regression analysis adjusted for baseline age, gender, race, physical activity, alcohol consumption, education, body weight, systolic BP, and urinary sodium excretion, the odds of hypertension was reduced by 77% (odds ratio 0.23; 95% confidence interval 0.07 to 0.76; P=0.02) in the weight loss group and by 35% (odds ratio 0.65; 95% confidence interval 0.25 to 1.69; P=0.37) in the sodium reduction group compared with their control groups. Hypertension 2000 Feb;35(2):544-9

Salt Sensitive Die Young: 17 yr study of 708 found that salt sensitive twice as likely to die. Weinburger, Indiana Univ, 10/25/00 meetings of American Heart Association's Council for High Blood Pressure Research. Only 10% salt from shaker and 85% in processed foods. Also increases calcium loss and osteoporosis. DASH study found reduced sodium diet cut BP in almost everyone.

Eat Less Animal Protein & Salt for Kidney Stones: A diet of less than 2500 mg sodium and 50 mg animal protein reduced both calcium and oxalate in urine in 5 year prospective study of 68 men. Those on reduced calcium diet actually had an increase of oxalate in urine. NEJM 346:77, 124, 2002

ACE-2 Deficient Rats Salt Sensitive: Angiotensin-converting enzyme 2 (ACE2), might also link lifestyle and health. Rats with low levels of the protein develop high blood pressure on a high-salt diet. They also have difficulty with heartbeat in middle age. Angiotensin-II makes BP go up. ACE-2 chops a bit off and makes BP go down. ACE is enzyme producing Angiotensin-II, so ACE-inhibitors are used to block HBP. Nature 6/20/02

Cutting Salt Nationally Would Hurt Pop Sales: 9/21/01 Nature. England’s government refused to go along with expert panel recommendation to lower national sodium intake from 9 to 6 grams. Cross-ownership of pop and salty snacks is quite extensive. Sales of both cause HBP and obesity.  The industry successfully lobbied the government to disregard the recommendations. 

HBP Linked to Bone Loss: 3676 white women over 65 followed for 3 ½ yr. Those with Systolic BP >147 suffered twice the bone loss as those <124. Jos. Zmuda, U Pitt, Lancet 9/18/99. 97% of calcium in bones. Anti-hypertensive drugs didn’t change bone-loss. Hormone replacement reduced the loss by half. Salt siphons calcium out of the body and high-salt diets lead to HBP and may be the cause of the association.

63% Increase in CVD Death in Overweight High in Salt: NHANES study found the 25% of subjects who were overweight were more sensitive to salt. Also, there was an 89% increase in strokes for each 100 mmol sodium (about 2200 mg salt). JAMA 21/1/99 or 00

Spinach, Cabbage, Tofu Help Stomach CA, Salty & Pickled Bad: Stomach cancer Korea’s most prevalent cancer. case-control study increased risk from broiled meats and fishes, salted side dishes (salted/fermented fish products) and salty stewed foods, such as soybean paste thick stew. Frequent consumption of mung bean pancake, tofu, cabbage, spinach and sesame oil decreased the risk. For meat and fish, pan frying was associated with decreased risk, whereas stewing or broiling was associated with increased risk. Pickled vegetables increased the risk, whereas fresh vegetables did not. In a recent cohort study in Seoul, green vegetables and soybean foods were associated with a decreased risk of stomach cancer. Case-control and cohort studies have reported that ginseng intake decreased the risk of gastric cancer. : Int J Cancer 1997;Suppl 10:7-9

Salt Linked to Stomach Cancer: Sodium, red meat and protein are all positively associated with stomach cancer, while citrus and fresh fruit, sugar, garlic, legumes, vegetables, and olive oil and anti-oxidants are all negatively associated. Italy. 382 cases, 561 controls. If there is a positive family history and high red meat, the Relative Risk of stomach cancer is 25.7 or 2400% higher! Cancer Res 7/2001;5415-9

Salt, Soy Sauce, Cigs Cause Gastric Ulcers: A study of over 7000 Jap-Americans in Hawaii for 20 years found 280 gastric and 150 duodenal ulcers. Both were increased with smoking and gastric were increased with salt or soy sauce. Alcohol had no impact. Fruit and milk no benefit. Am J Epidemiol 1992 Mar 1;135(5):521-30

Fruits, Vegetables, Low Salt, Low-Fat Dairy Lower BP Dramatically: DASH: Randomized feeding study. 412 adults with untreated systolic 120-160, diastolic 80 to 95 mm Hg. Followed the DASH diet or a control (typical U.S.) diet for three consecutive 30-day feeding periods, during which sodium intake (50, 100, and 150 mmol/d at 2100 kcal) varied according to a randomly assigned sequence. Body weight was maintained. In all subgroups, the DASH diet and reduced sodium intake were each associated with significant decreases in blood pressure; these two factors combined produced the greatest reductions. Among nonhypertensive participants who received the control diet, lower (vs. higher) sodium intake decreased blood pressure by 7.0/3.8 mm Hg in those older than 45 years of age (P < 0.001) and by 3.7/1.5 mm Hg in those 45 years of age or younger (P < 0.05). Ann Intern Med 2001 Dec 18;135(12):1019-28; Reducing the sodium intake from the high to the intermediate level reduced the systolic blood pressure by 2.1 mm Hg (P<0.001) during the control diet and by 1.3 mm Hg (P=0.03) during the DASH diet. Reducing the sodium intake from the intermediate to the low level caused additional reductions of 4.6 mm Hg during the control diet (P<0.001) and 1.7 mm Hg during the DASH diet (P<0.01). The effects of sodium were observed in participants with and in those without hypertension, blacks and those of other races, and women and men. The DASH diet was associated with a significantly lower systolic blood pressure at each sodium level; and the difference was greater with high sodium levels than with low ones. As compared with the control diet with a high sodium level, the DASH diet with a low sodium level led to a mean systolic blood pressure that was 7.1 mm Hg lower in participants without hypertension, and 11.5 mm Hg lower in participants with hypertension. The reduction of sodium intake to levels below the current recommendation of 100 mmol per day and the DASH diet both lower blood pressure substantially, with greater effects in combination than singly. Long-term health benefits will depend on the ability of people to make long-lasting dietary changes and the increased availability of lower-sodium foods. Sacks, Harvard, N Engl J Med 2001 Jan 4;344(1):3-10

Salted and Smoked Fish, Cured Meat Linked to Stomach Cancer: A 24 year follow-up study found 189 cases in 9985 Finnish adults. High salted and smoked fish had an RR of 2.45 and high cured meat an RR of 1.85. No link with other fish intake.

Sweet Potato, Poverty, Salt Assoc to Stomach CA: Risk factors of gastric cancer were living in high incidence area for a long period, low economic income, low animal protein intake, high sweet potato and inkfish intake, eating and drinking too much at one meal and mental injuring. The risk factors of severe dysplasia were low intake of protein, intake of non-fresh fish, large intake of inkfish and salted meat, a family history of gastric cancer. Zhonghua Liu Xing Bing Xue Za Zhi 1993 Oct;14(5):295-9

Japanese Finds Salt Linked Osteoporosis: 1658 adult females tested for sodium and calcium excretion and bone density. Urinary sodium and calcium excretion were found to be linked r=.438. Also found some evidence linking sodium intake and decreased bone mineralization. Clin Exp Pharm Physio 7/99;26:573

Salt Harmful to Calcium in Girls: 8- to 13-year-old girls used nearly all the calcium in their diets unless their were heavy salt users in which case they excreted large amounts of calcium even if they did not consume sizable amounts of sodium. Ohio State. Child Mag 11/2000 p. 43. The U.S. government says 225-500 mg/day of sodium is needed and a limit of 2000 mg recommended. However, boys average 3200 mg and girls 2800 or at least six times the maximum required. Even toddlers average 2600.

Salt increases Calcium Excretion: For every 100 mmol of sodium, 1 mmol of calcium is taken out of the body. Protein is another negative risk factor with 40-80 g/d increasing calcium excretion by 1 mmol. Ann NY Aca Sci 11/20/98

Salt Exacerbates Asthma: Epidemiological data show assoc between asthma mortality and regional purchases of table salt. Also, dietary salt restriction in asthmatics results in fewer symptoms with lower consumption bronchodilators. Clin Exp Pharm Physio 3/95;22:180

Salt Increases Left Ventricular Mass: Many studies show a correlation between sodium excretion and LV hypertrophy. Salt restriction shown reduce LV mass. Clin Exp Pharm Physio 3/95;22:180

Salt exacerbates asthma, osteoporosis, renal disease, and carcinoma of the stomach: Am J Hypertens 5/97

Asthma Not Associated with Dietary Salt in Montreal Study but Some Harmful Effects in Zurich, UK, Italy Studies: 145 kids with asthma and similar number of controls. Bronchial hyperresponsiveness did increase with high salt intakes. Usual dietary salt intake and asthma in children: a case-control study. Demissie K, Ernst P, Gray Donald K, Joseph L. Thorax. 1996 Jan;51(1):59-63. Small study and case-control studies are not as sensitive.; Zurich study found, "Patients with bronchial asthma seems to be salt-sensitive, the responsible ion being presumably sodium. A low-salt diet appears to have a favorable effect in patients with asthma and to reduce the need for anti-asthma drugs." Chest. 1993 Oct;104(4):1138-43; Also, in DBPC 27 mild-mod asthmatics in Leicester, "Our results suggest that large increases in dietary sodium result in physiological deterioration and increased morbidity in male asthmatic patients." Thorax. 1993 Jul;48(7):714-8; And Italy. "personal table salt use is related to an increased prevalence of bronchial symptoms" Eur Respir J. 1993 Apr;6(4):517-22

Asthma, Exercised-Induced Less on Low Salt: greater airway resistance during the high salt diet. In conclusion, the low salt diet improved and the high salt diet exacerbated pulmonary function during exercise in individuals with exercise-induced asthma. DB PC crossover study of 15 with exercise induced asthma. Univ Wales, Dietary salt alters pulmonary function during exercise in exercise-induced asthmatics. Mickleborough TD, Gotshall RW, Cordain L, Lindley M. J Sports Sci. 2001 Nov;19(11):865-73. The authors had previously shown that a low salt diet improves and a high salt diet exacerbates post-exercise pulmonary function in individuals with exercise-induced asthma. Med Sci Sports Exerc. 2000 Nov;32(11):1815-9.