Nutritional Medicine , Separating Fact from Fiction
You have heard it before. Cut down on salt. It’s bad for you. You know that already. But, do you know how much is too much? Or, how to tell if you are taking in too much sodium? What about if salt is the same thing as sodium and how do you figure all of this out?Is there a downside to limiting sodium? Well, if you are like most people, you just try not to use the salt shaker or buy a salt substitute. Right? Wrong…
What about the iodine in iodized salt? If sodium is limited will enough iodine be obtained through the diet to prevent goiter or non-immune forms of hypothyroidism? What does iodine have to do with the thyroid gland and its function in metabolism, weight control, thermogenics? Iodine is necessarily obtained from the diet as we cannot make it and if sufficient iodine (along with other nutrients) are not present fatigue, weight gain, mental retardation (in infants of deficient mothers) among other maladies, may occur.
How did iodine get in our salt anyway? In 1924, iodized salt was introduced in the United States to reduce the goiter rate. This intervention rapidly reduced the incidence of iodine deficiency. India also followed suit with this preventive health measure. "Goiter" hypothyroidism quickly dropped. Worldwide, iodine deficiency affects about two billion people and is the leading preventable cause of intellectual and developmental disabilities. Iodizing salt was a cheap and effective public health treatment program.
What is salt? Many conceptualize salt as the same thing as sodium. False. Salt is a combination of 40% sodium and 60% chloride, so it is not all sodium. Salt substitute is potassium chloride, no sodium at all. And, a teaspoon of iodized salt (6 grams) contains about 2,300 mg of sodium and 300 mcg of added iodine. Appalachian salt and sea salt contain negligible iodine.
How much sodium is healthy? The 2015-2020 Dietary Guidelines for Americans recommend no more than 2,300 mg per day for optimal health. Too much sodium can cause high blood pressure (in sodium sensitive individuals), water retention or edema, increased weight, a slow loss of bone mass and will increase a child’s blood pressure. However, as nasty as too sodium can be, we need some sodium to function and even more sodium in high heat or periods of intense sweating. Most Americans eat 3,400 mg of sodium per day.
How can limiting sodium cut my health risks?
Limiting sodium can prevent 32,000 myocardial events per year or 20,000 strokes. It may reduce the number of people with hypertension in the US by nearly 11 million. Thinking in terms of a decade over $100 billion healthcare dollars could be saved.
Has anyone thought about how limiting salt will affect iodine deficiency?
Cutting down on sodium is not the same as limiting salt. Many Americans (and other cultures as well) consume little iodine. Iodine is necessary for proper thyroid function and the thyroid regulates among other things, metabolism, weight and growth. At one time, it was common to take care of iodine deficiency by adding it to the salt. Incidences of hypothyroidism due to iodine deficiency declined. Now, according to recent studies, we are at almost epidemic levels again in both the US and India for low thyroid function. Iodine in the amounts of about 100 micrograms/day is needed for adult men and women. The need in pregnancy almost doubles.
Now, here is the oxymoron. You want to get enough iodine in your meals, but most doctors agree that taking iodine supplements and getting too much iodine can be dangerous as well possibly even initiating an autoimmune type of low thyroid called Hashimoto's thyroiditis.
How to lower sodium yet preserve iodine intake thus optimizing thyroid function
Where is most of the sodium found lurking in our diet? Well, take a look at any processed food label. Is it iodized salt that you see? No. It is sodium. And, it is sodium used in restaurant foods (you never can really tell) and fast foods where an abundance of our people eat. So, how do you cut down on sodium without compromising your thyroid?
Egg 1 large 24 mcg
Cod 3 oz 99 mcg
yogurt 1 cup 75 mcg (low fat)
Milk 1 cup 56 mcg (reduced fat)
Seaweed 1 g varies between 16 & 2,984 mcg
Iodized Salt 1/4 tsp. 71 mcg
* National Institutes of Health accessed 8/21/17
Sodium Content of Select Foods*
Cocoa Powder 950 mg per 5 grams
Cornflakes 1,170 mg per 30 grams
Mac 'n Cheese 280 mg per 180 grams
Apple 2 mg per apple
So, a low sodium diet should include the proper attention to where sodium is often hidden (fast foods, restaurant foods, packaged/processed foods). Attention at the same time should be on achieving adequate, but not excessive, iodine preferably from foods. And, if you happen to have hypothyroidism, try to get the daily recommended amount of iodine in without resorting to supplement such as kelp or Thyroid Support Supplements. A balanced eating plan will meet iodine needs while still reducing sodium to less than 2,300 mg/day.
Frieden, T. Sodium reduction – Saving lives by putting choice into consumers’ hands. 2016. JAMA. Soi:10.1001/jama.2016.7992
Note on Comment: Salt can be unhealthy in excess. However, the body does need some sodium to survive, not salt necessarily, but sodium. Salt comes in two forms, iodized and uniodized. The important point to take home is that since we are no longer relying on salt fortification for iodine, we need to pay attention to getting adequate amounts of iodine, particularly if on a low sodium diet and have abandoned the salt shaker or if you choose not to use iodized salt.