Make Sure Iodine is in Your Prenatal

Although severe iodine deficiency was eliminated in the United States nearly a century ago after the introduction of iodized salt, iodine intake has declined in recent decades. “Public health efforts to limit salt intake to decrease cardiovascular risk, in conjunction with increasing use of kosher salt and sea salt (neither of which contain iodine),” may in part be to blame. Not adding salt to foods is a good thing, as sodium is considered the second leading dietary killer in the world (second only to not eating enough fruit), but if you do add table salt, make sure it’s iodized. “It is a myth (often also false advertising) that ‘natural’ sea salt contains significant amounts of iodine.”

Fruits and vegetables provide iodine, but the amounts can vary depending on where it’s grown and how much iodine is in the soil. Because iodine is particularly important for fetal brain development, there’s a recommendation that “all US women who are pregnant, lactating, or even planning a pregnancy should ingest dietary supplements containing 150 mcg of potassium iodide per day,” which I discuss in my video Iodine Supplements Before, During, and After Pregnancy.

Is there evidence they’re not getting enough? We’d like to see urine levels over 150 mcg/L in pregnant women, but in the United States, pregnant women only average about 125 mcg/L. For example, a recent survey in New York City showed only about half of pregnant women were making the cut.

Don’t most pregnant women take prenatal vitamins, though? Only about half of prenatal multivitamins contain any iodine at all, and so only about one in five pregnant women in the United States are following the recommendations of the American Thyroid Association to take a daily iodine supplement, specifically in the form of potassium iodide rather than seaweed, as the levels in seaweed are subject to natural variability. Though the iodine content was as much as 90 percent off in some of the potassium iodide prenatal supplements, the kelp supplements varied even wider, off by as much as 170 percent.

Now, the American Thyroid Association admits it doesn’t have evidence that the current borderline insufficiency levels are leading to undesirable outcomes and so its rationale that all pregnant women take iodine supplements is a bit tenuous. Until such data are available, though, it figures better safe than sorry.

A randomized, placebo-controlled, interventional trial would answer the question once and for all, but the existing evidence for iodine supplementation during pregnancy is so convincing that it would be considered unethical to randomize pregnant women to a placebo.

When it comes to sufficient iodine intake during pregnancy, I’d recommend: Just do it.


Women eating plant-based diets may find this video of special importance: Pregnant Vegans at Risk for Iodine Deficiency.

This isn’t to say sea vegetables aren’t good for you in their own right. See Which Seaweed Is Most Protective Against Breast Cancer?.

For more videos on having a healthy pregnancy, see:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

Why We Should Cut Down on Salt Independently of Blood Pressure

If you put people on a low-salt diet, meaning only getting twice as much sodium as they need, as opposed to a usual salt diet where they’re getting five times more, you get a significant improvement in artery function. Lower salt begets better arterial function, suggesting heart-protective effects beyond just blood pressure reduction. Now, this was after dropping people’s salt intake by about a teaspoon a day for two weeks. What if you only dropped salt intake by a half teaspoon or so a day? You still get a significant improvement in artery function, and it happens within just two days of reducing one’s salt intake—or, even after a single meal. A high-salt meal, which is to say just a “typical amount of salt consumed in a commonly eaten meal, can significantly suppress [artery function] within 30 [minutes].” In my video Sodium and Arterial Function: A-Salting Our Endothelium, I show what happens 30, 60, 90, and 120 minutes after consuming a meal with just a pinch of salt in it versus eating the same meal, but made with a quarter teaspoon of salt rather than a pinch: a significant suppression of arterial function. Now, is this in addition to the spike in blood pressure from salt or because of the spike in blood pressure?

If you take people with normal blood pressure and give them a bowl of soup containing the amount of salt a regular meal might contain, their blood pressure goes up over the next three hours compared to the same soup with no added salt. Now, this doesn’t happen to everyone; this is just the average response. Some people are resistant to the effects of salt on their blood pressure. So what if you repeated the artery function experiment on them? You get a paper entitled (*spoiler alert*): “High dietary sodium intake impairs endothelium-dependent dilation in healthy salt-resistant humans.” Indeed, even in people whose blood pressure is unresponsive to salt intake, they still suffer significant suppression of their artery function. So, independent of any effects on blood pressure, salt hurts our arteries, and that harm begins within minutes of consumption for our major arteries and even our tiny blood vessels.

Using something called laser Doppler flowmetry, you can measure blood flow in the tiny vessels in our skin. In the video, you can see the measurement of blood flow at baseline. Now, to get the blood vessels to open up, they warmed the skin. The reason we may turn pink when we get into a hot bath is that the blood vessels in our skin are opening up, and that’s what happened: a big increase in blood flow with the warming. That was on the low-salt diet, however. A high-salt diet starts out the same, but after the same warming, there’s significantly less blood flow. The arteries just don’t seem to open up as well on a high-salt diet, unless you inject vitamin C into the skin. That seems to reverse the salt-induced suppression of blood vessel function. So if an antioxidant reverses the salt effect, then the way salt may be damaging our artery function is through oxidative stress, the formation of free radicals in our blood stream. But, how?

There’s an enzyme in our body that can detoxify a million free radicals per second (!), 24 hours a day, 7 days a week. But, compared to a low-salt diet, if we consume a normal-salt diet, we suppress the activity of this detoxifying powerhouse of an enzyme. That may help explain why our artery function is much lower on salt. With our antioxidant enzymes crippled by the salt, all the excess free radicals may be crippling our arteries. Mop up those extra free radicals by infusing vitamin C into the bloodstream, however, and artery function returns to normal. In contrast, on a low-salt diet, if you drip vitamin C into people’s veins, nothing happens because our antioxidant enzymes are already taking care of business and haven’t been shackled by the sodium of a normal-salt diet.

Whereas potassium, concentrated in fruits and vegetables, softens the cells that line our arteries and increases the release of nitric oxide that allows our arteries to relax, sodium in our blood stiffens the artery lining within minutes and reduces nitric oxide release. The more salt, the less nitric oxide is produced. Consume one salty meal, and not only does our blood pressure go up, but our arteries literally stiffen. That’s why we could figure out four thousand years ago that too much salt was bad for us. Maybe we don’t need a double-blind trial. Maybe we don’t need to follow people around for a decade. We may just have to feed someone a bag of potato chips and take their pulse.


My video Sodium and Arterial Function: A-Salting Our Endothelium is part of an extended video series on sodium, trying to set the record straight on the “controversy” manufactured by the processed food industries. Check out the other installments:

Other salt-related videos of interest include:

I touched on potassium in Preventing Strokes with Diet and Lowering our Sodium-to-Potassium Ratio to Reduce Stroke Risk, but I’m looking forward to doing a deep dive into the mineral when I get a chance.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

Reversing Massive Obesity With Diet

Dr. Walter Kempner introduced the first comprehensive dietary program to treat chronic kidney disease and, in doing so, also revolutionized the treatment of other disorders, including obesity. Kempner was Professor Emeritus of Medicine at Duke, where he came up with the so-called rice diet, which basically consisted of rice, sugar, fruit, and fruit juices, was extremely low in sodium and fat, and included no animal fat, no cholesterol, and no animal protein. The sugar was added as a source of calories so people wouldn’t lose too much weight. But some people need to lose weight, so he started treating obese patients with a lower calorie version of the diet, which I discuss in my Can Morbid Obesity Be Reversed Through Diet? video.

He published an analysis of 106 patients who each lost at least 100 pounds. Why 106? Kempner simply picked the last 100 people who lost more than 100 pounds, and, by the time he finished reviewing their charts, 6 more had joined the so-called century club. Average weight loss among them was 141 pounds. “This study demonstrates that massively obese persons can achieve marked weight reduction, even normalization of weight, without hospitalization, surgery, or pharmacologic intervention…[O]ne important fact to be gained from this study is that, despite the misconception to the contrary, massive obesity is not an uncorrectable malady. Weight loss can be achieved, massive obesity can be corrected, and it can be done without drastic intervention.”

Well, Kempner’s rice diet is pretty drastic, so definitely don’t try this at home. In fact, the rice diet is dangerous. It’s so restrictive that it may cause serious electrolyte imbalances, unless the patient is carefully medically supervised with frequent blood and urine lab testing. Dangerous? Says who? Said the world’s number-one advocate for the rice diet: Dr. Kempner himself.

The best, safe approximation of the diet, meaning low in sodium and without fat, protein, or cholesterol from animals, would be a vitamin B12-fortified diet centered around whole, unprocessed plant foods. However, even a medically supervised rice diet could be considered un-drastic compared to procedures like getting one’s internal organs stapled or rearranged, wiring someone’s jaws shut, or even undergoing brain surgery.

Attempts have been made to destroy the parts of the brain associated with the sensation of hunger, by irradiation or going in through the skull and burning them out. “It shows how ineffective most simpler forms of treatment are that anyone should think it reasonable to produce irreversible intracranial lesions in very obese patients.” The surgeons defended these procedures, however, explaining that their “justification in attempting the operation is, of course, the very poor results of conventional therapy in gross obesity, and the dark prognosis, mental and physical, of the uncorrected condition.” In reply, a critic countered, “Such strong feelings [about how dark the prognosis is] run the risk of being conveyed to the patient, to the effect of masking the operative dangers and steam-rolling the patient’s approval.” The surgeon replied, “If any ‘steamrolling’ is taking place, it comes rather from obese patients who sometimes threaten suicide unless they are accepted for experimental surgical treatment.”

As of 2013, the American Medical Association officially declared obesity a disease, by identifying the enormous humanitarian impact of obesity as requiring the medical care and attention of other diseases. Yet the way we treat diseases these days involves drugs and surgery. Anti-obesity drugs have been pulled from the market again and again after they started killing people—an unrelenting fall of the pharmacological treatment of obesity.

The same has happened with obesity surgeries. The procedure Kempner wrote about was discontinued because of the complication of causing irreversible cirrhosis of the liver. Current procedures include various reconfigurations of the digestive tract. Complications of surgery appear to occur in about 20 percent of patients, and nearly one in ten of which may be death. In one of the largest studies, 1.9 percent of patients died within a month of the surgery. “Even if surgery proves sustainably effective, the need to rely on the rearrangement of [our] anatomy as an alternative to better use of feet and forks [that is, diet and exercise] seems a societal travesty.”


For more on Kempner and his rice diet, see my videos:

Learn more on the surgical approach in Reversing Diabetes with Surgery and Stomach Stapling Kids.

And, for more on weight, see:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations: