Natural Ingredients and Kidney, Liver or Thyroid Conditions

Urgent first. If someone collapses, has trouble breathing or has a seizure after swallowing a mineral salt, a "cleanse" or a supplement, call 911. For a swallowed product with milder symptoms, call Poison Help at 1-800-222-1222 (US), free and confidential. [1] Other countries: Poison Help by Country.

Short answer. For most healthy people, everyday foods are not the concern here. The cautions in the sources we read cluster around concentrated or swallowed products: kelp and seaweed supplements (thyroid), magnesium salts and baking soda (kidneys and salt balance), and herbal or multi-ingredient supplements (liver). "Natural" does not always mean "safe." [2]

The thyroid: seaweed and iodine

Iodine is needed to make thyroid hormones, and seaweed can be a rich source. MedlinePlus calls kelp a rich source of iodine and says very high intake can reduce thyroid function. [3] A 2019 review says that in some people too much iodine may bring on an overactive or underactive thyroid, goiter or thyroid autoimmunity, and that people with existing thyroid disease or past iodine deficiency may be more susceptible. [4]

The American Thyroid Association (ATA) says many iodine, potassium iodide and kelp supplements contain iodine in amounts up to several thousand times the daily tolerable upper limit, and it advises against iodine and kelp supplements containing more than 500 mcg iodine daily. [5] It names infants, older adults, pregnant and breastfeeding women and people with thyroid disease as more susceptible. [5]

MedlinePlus also lists seaweed-based supplements among sources of iodine that can push the thyroid to make too much hormone, and advises people with an overactive thyroid to ask their provider which foods and supplements to avoid. [6] For the full picture see Seaweed, Iodine and the Thyroid and Thyroid Conditions: Iodine, Biotin and Herbal Products.

The kidneys: magnesium salts, baking soda and colon cleanses

Healthy kidneys remove extra magnesium, so side effects from high magnesium intake are uncommon except in people with significantly reduced kidney function. MedlinePlus says excess most often occurs with too much magnesium in supplement form or with magnesium-containing laxatives. [7] Epsom salt is magnesium sulfate, and swallowing it is the risky use.

Two case reports show the stakes. In one, a 60-year-old woman with earlier stomach surgery lost consciousness 30 minutes after swallowing Epsom salts; the authors report near-fatal high magnesium despite normal kidney function, and she recovered with emergency treatment. [8] In another, a woman with long-term constipation treated with magnesium laxatives died; the authors say severe high magnesium often ends in death even when kidneys are normal. [9] These are rare, individual cases, not a measure of how often harm happens.

Baking soda is sodium bicarbonate. Poison Control says a large amount can cause seizures, dehydration and kidney failure, and advises against using it as a homemade antacid. [10] See Epsom Salt Taken by Mouth as a Laxative and Baking Soda for Heartburn.

NCCIH says colon-cleansing procedures can have serious side effects and harm is more likely with a history of kidney disease, among other conditions. [11] It also says there is some evidence that colloidal silver can cause kidney, liver or nervous system problems, and that it can reduce absorption of thyroxine, a thyroid medicine. [12]

The liver: herbal and multi-ingredient products

NCCIH says more cases of sudden liver damage are being reported in people taking dietary supplements, and it can be severe. [2] A 2017 symposium report says herbal and dietary supplements account for 20% of cases of liver toxicity in the United States based on research data, and that most cases involve multi-ingredient products where the responsible ingredient is often unknown. [13]

Proper evidence not found, in the sources we read, for ingredient-by-ingredient liver ratings of the foods and oils in this library. We could not read the NIH LiverTox database (it blocked our access), so we do not quote it. That gap is not proof of safety.

Liver disease often causes no symptoms early on. [14] The NHS says yellow skin or eyes can signal something serious such as liver disease and needs urgent medical help. [15] More: Liver Safety and Supplements.

What the sources found, at a glance