Introduction: The Belief that Added Salt is Paleo
Look no further than the increasing number of bestselling “Paleo” diet cookbooks1-7, or “Paleo” diet website recipes8-16 and you can fully appreciate the near unanimity of authors whose recipes embrace sea salt or salt as fundamental ingredients in an otherwise Paleo-friendly meal. Somehow, somewhere most people in the Paleo community have been led to believe that added sea salt or salt can be safely included in contemporary Paleo diets with no long-term, adverse health effects, and that high salt intakes were a normal part of ancestral, hunter-gatherer diets.
At least, this is a notion gaining popularity among many bloggers in the Paleosphere4-7,16-22. But the internet is somewhat of a wild west of information that doesn’t go through the rigorous checks and balances of scientific publishing. In contrast, scientists and physicians from the Paleo community, including S. Boyd Eaton (M.D.), Staffan Lindeberg (M.D., Ph.D.), Pedro Bastos (M.S., Ph.D. candidate) Lynda Frassetto (M.D.), Anthony Sebastian (M.D.), James O’Keefe (M.D.), myself (Ph.D.) and others, have largely rejected the notion that high salt intakes were typically present in ancestral hunter-gatherer diets. We believe that high consumption of sodium does indeed produce long-term, adverse health effects in contemporary people23-43. Re-evaluation from numerous avenues of previously published data indicates that high salt/sodium consumption by our hunter-gatherer ancestors would have been implausible, or rare at best.
Further, important new evidence from an extensive 20-year study of salt ingestion on mortality, supports the physiological argument that high dietary salt intakes produce adverse health effects53-55.
New Scientific Evidence: Salt Consumption Increases Adverse Health Risks at Even Moderate Levels.
In 2005, the U.S. Department of Health and Human Services recommended that adults in the U.S. consume no more than 2300 mg of sodium per day (5.8 grams of salt)44. Additionally, people in specific groups (those 51 years of age or older, people with high blood pressure, diabetes, kidney disease and adults of African American ethnicity should consume no more than 1500 mg of sodium per day (3.8 grams of salt)44. Other worldwide organizations including The American Heart Association45, the World Health Organization46 and the government of England and Wales46 have made similar recommendations to reduce dietary sodium.
Okay – scientific agencies and organizations worldwide have made near universal recommendations to reduce dietary sodium intake to 2300 mg per day, corresponding to 5.8 grams of salt. Admittedly, we have disagreed with these organizations on other recommendations – particularly dietary fat – however, 24-hour urinary tracking makes it much easier to study the effects of sodium consumption compared to nutrients like fat. So, in this case, we feel both the research and the Paleolithic template lines up well with the recommendations.
Yet, an article on one Paleo website stated, “I feel that the data supports an intake between 3000 and 7000 milligrams of sodium . . . per day”17. Other Paleo bloggers16 have made similar claims4-6, 7, 18, 19-22.
So, what are the health effects if you decide to eat salted foods and increase your sodium intake above 2300 mg/day as almost all of these bloggers4-6, 7, 18, 19-22 advise?
This is a question that even the scientific community has been exploring more extensively in recent years. Some researchers have suggested “U” or “J” shaped relationships may exist between sodium intake and cardiovascular disease (CVD) risk56-58, meaning that high sodium consumption increases the risk of CVD, but so does low sodium consumption. This “U” shaped relationship has led some scientists to suggest that we should consume more than the recommended daily allowance of sodium.
However, methodological issues exist with studies showing a “U” or “J” shaped relationship between CVD risk and sodium intake. First, these studies used overnight or spot urinary sodium evaluations rather than the “gold standard” 24-hour urinary sodium measurements. Hence considerable errors may exist in the estimation of dietary sodium intake in these studies56-58. This may invalidate their results53.
Second, these studies may have incorrectly attributed cause and effect. When a patient is diagnosed as hypertensive and at high risk for CVD, the primary recommendation of doctors practicing western medicine is to significantly reduce sodium intake. This recommendation could explain why low sodium intakes are associated with higher rates of CVD and the “U” or “J” shaped relationships exist. It appears that the low sodium consumption wasn’t causing CVD, but rather the disease was causing the low consumption53.
Most recently, a large randomized controlled trial (The TOPH trial) involving 3,126 subjects over a 24-year period, explored the health impact of sodium consumption while addressing the above two methodological issues with previous studies. The two TOPH randomized controlled trials – one for all-cause mortality53 and the other for cardiovascular disease (CVD) risk54 – employed the “gold standard” 24-hour urinary sodium collection procedure to estimate dietary sodium intake55. The researchers also did not include subjects who had been previously diagnosed as hypertensive55.
The results clearly showed an increased risk of all-cause mortality (death) with increasing sodium intake53. An important point stands out from this trial – the authors demonstrated that at even the lowest levels of sodium intake, a direct linear relationship existed with mortality (see Figure 1 below).
This information paints a grim picture about adding salt or sea salt to your diet. Your risk of dying from all causes increases proportionately with increased sodium intakes. The results of this study are consistent with an earlier TOPH trial, also demonstrating a linear and decreased risk of CVD, as sodium intake was lowered from 3600 mg/day to 2300 mg/d and then to 1500 mg/day54.
A recent meta-analysis (examination of multiple studies) of 34 randomized controlled trials of salt restriction, involving 3,230 participants and lasting for at least four weeks, showed a mean reduction in systolic blood pressure of 4.2 mm Hg with an accompanying decline in diastolic blood pressure of 2.1 mm Hg59. The authors concluded, “A modest reduction in salt intake for four or more weeks causes significant and, from a population viewpoint, important falls in blood pressure in both hypertensive and normotensive individuals, irrespective of sex and ethnic group”. Further, a meta-analysis of 13 prospective studies (following an event before it occurred and then after it occurred) involving 177,025 participants, demonstrated that a higher salt intake was associated with a greater risk of stroke60.
Further, many studies are revealing that the ratio of potassium to sodium in our diet is as important as sodium levels alone. A meta-analysis of eleven studies that included 247,510 male and female participants showed that higher daily potassium consumption was associated with a 21% reduction in the risk of stroke61.
Other Adverse Effects of High Salt Consumption
If you decide to not worry about sodium and cook with sea salt and refined salt, your risk of cardiovascular disease and all-cause mortality will increase. But these are not the only known adverse effects of adding mined sea salt and refined salt to your diet. Higher intakes of sodium increase the risk of certain cancers62-64, autoimmune and immune diseases65-68, as well as multiple diseases involving chronic low level, systemic inflammation65-70. Further high salt ingestion is known to disturb sleep patterns and cause insomnia71.
Sodium may also affect the length of our telomeres – the “caps” on the end of our DNA. Shortening of telomeres has been associated with aging72,73. A recent 2015 study found that salt consumption correlated with telomere length in overweight and obese adolescents. However, this study suffered from methodological issues tracking sodium consumption74.
Where’s the Salt?
Perhaps the best evidence for a low salt diet comes simply from inspection of the foods we eat. If high salt diets were a normal part of human physiology, then you would expect to find high concentrations of sodium in many of the natural, unsalted foods we eat. As we will shortly point out, nothing could be further from the truth. Almost all non-processed, non-salted foods in contemporary Paleo Diets contain low concentrations of sodium. Similarly, virtually, all wild, non-domesticated foods are quite low in sodium, as we will demonstrate in a future blog.
Fortunately, you don’t have to be a trained nutritionist to evaluate sodium in the USDA food tables and understand that high sodium foods are rarely or infrequently consumed in their natural, unsalted condition. This is simply because, with few exceptions, they don’t exist.
Let me summarize the USDA food data on sodium so you can see for yourself that it would be nearly impossible to consume a high salt diet on unadulterated natural foods. Table 1 below lists the sodium and potassium concentrations of contemporary foods in their natural, unsalted, unadulterated state:
Table 1. Sodium and potassium concentrations in contemporary natural foods.
These food items are categorized by food groups (meat, organ meats, seafood, eggs, milk, vegetables, nuts and seeds, fruits, starchy roots, legumes, and whole grains). Note that three of these categories (whole grains, milk and legumes) are not included in contemporary Paleo diets. The various items in each of the 11 food categories were not selected randomly, but represent the most commonly consumed foods in the U.S. in each category. For instance, the 20 fruits listed in the “Fruits” category represent 20 of the most commonly consumed fruits in the U.S.
A quick examination of Table 1 l shows that consumption of reasonable combinations of contemporary, unsalted, natural foods yields sodium intakes considerably lower than 2300 mg/day Note that suggested daily caloric intakes for women are 1600-2000 kcal/day and for men are 2400-2600 kcal/day.
Table 2 below averages the foods in each category from Table 1 to show daily sodium consumption for 11 food categories in men and women eating natural foods at normal daily caloric intakes without adding salt:
Table 2. Average sodium (Na) intakes for women eating between 1600 to 2000 kcal per day and for men eating between 2400 to 2600 kcal per day for 11 food categories if daily calories were met by eating only that food group.
Table 2 shows that consumption of fresh, unprocessed foods, yields daily intakes of sodium which could have rarely or infrequently exceeded the governmental and institutional limits of 2300 mg/day. In fact, to exceed limits would require a diet consisting almost entirely of seafood and even then, the seafood would have to be primarily shellfish. It is also technically possible to slightly exceed recommendations eating only vegetables, but that would require eating a lot of celery. However, try eating enough celery in a day to hit 2300 mg of sodium – that’s 72 stalks! Perhaps 55 carrots sound more reasonable?
Are you starting to see the measures you’d have to go to on a natural diet with no added salt to exceed current sodium recommendations? Under normal food category selection by free-living people, sodium consumption would be significantly lower than the recommended daily allowance. So, readers I encourage you again to ask the simple question; “where’s the salt in natural unadulterated foods?”
Paleo dieters, consider this data. Fresh fruits contain a paltry 70 mg of sodium per 1000 calories on average, nuts supply only 10 mg of sodium per 1000 calories on average, fresh meat yields low concentrations of sodium (377 mg Na/1000 kcal), and fresh vegetables average only 1020 mg of sodium/1000 kcal.
Both Tables 1 and 2 show the implausibility of regularly consuming a combination of contemporary, normal foods on a regular basis, which would exceed 2300 mg of daily sodium. Reaching a sodium intake of 7000 mg/day, day after day, week after week, and month after month (as suggested by one Paleo blogger17, would be virtually impossible. These kinds of excessively high sodium intakes can only be achieved by adding mined sea salt, or processed salt47, 48 to natural, real foods. The Paleo Diet is not about adding salt, preservatives or any other additives to food, but rather about eating real, unprocessed foods as they occur naturally.
The Ratio of Potassium to Sodium: The Most Important Dietary Factor
Inclusion of a significant amount (35% to 45%) of plant food (fruits, vegetables, nuts, certain tubers – without added salt or sea salt) into your diet virtually assures a low sodium intake, no matter what else you eat. But more importantly from Table 1 you can see that if you eat natural, unsalted foods, potassium intakes will always greatly exceed sodium intakes under all normal food group selections.
High potassium consumption has been demonstrated to override the negative health effects of a high salt intake38, 49-52. Unfortunately, the typical western dietary pattern not only produces high sodium intakes, but also low potassium intakes, because we so infrequently eat high potassium foods such as fruits and vegetables. Worse, the western diet is high in sodium-enriched, potassium-depleted processed foods (particularly sugar, refined vegetable oils, margarines and processed fats) 26. So the message here is to reduce your sodium intake from processed food; don’t add salt or sea salt to your Paleo recipes, and definitely include more potassium rich plant foods (fruits, vegetables, nuts and seeds) into your diet.
The Best Advice about Sodium in Your Paleo Diet
1. Be cautious when listening to dietary advice from Paleo bloggers.
2. Reduce your sodium intake mainly by eliminating or severely reducing processed food.
3. Don’t, or only infrequently, add salt or sea salt to your Paleo recipes.
4. Don’t worry about fresh meat or fish, they only contain moderate amounts of sodium.
5. Definitely include more potassium rich plant foods (fruits, vegetables, nuts and seeds) into your diet.
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