Life Extension Two-Per-Day Multivitamin Review 2026: Review

Possible side effects

• High blood calcium from vitamin D toxicity can lead to nausea, vomiting, muscle weakness, and other symptoms.

Serious risks

• Toxicity can cause high blood and urine calcium. In extreme cases it may lead to kidney failure, soft tissue calcification, heart rhythm problems, and death.
• Toxicity is almost always caused by taking too much vitamin D through supplements.

Avoid or ask a doctor first if

• The source says people on regular medications should talk with their health care providers about vitamin D intake and status.

Medication interactions

• Vitamin D supplements may interact with orlistat, statins, steroids, and thiazide diuretics.
• Taking calcium supplements with vitamin D supplements may raise the risk of certain adverse effects.

Serious risks

• The Food and Nutrition Board set no upper limit for B12 because its potential for toxicity is low.

Avoid or ask a doctor first if

• People who regularly take certain medications are told to talk with their health care providers about their B12 status.

Medication interactions

• B12 supplements may interact with some medications. Gastric acid inhibitors and metformin may affect B12 levels.
• Several types of medications might adversely affect B12 levels.

Serious risks

• High biotin intakes, possibly even intakes above the AI, may pose a health risk tied to lab testing.
• Biotin beyond recommended intakes can cause clinically significant falsely high or falsely low lab results, depending on the test.
• In a small study of six healthy adults taking 10 mg/day for 1 week, biotin falsely lowered N-terminal pro-brain natriuretic peptide, which could result in a failure to identify congestive heart failure. Thyroid stimulating hormone was also falsely lowered.
• Case reports describe findings falsely indicating Graves' disease and severe hyperthyroidism in patients taking 10–300 mg biotin per day.
• A single 10 mg dose of biotin has interfered with thyroid function tests given within 24 hours.
• Per FDA, a patient with a high intake of supplemental biotin died after a troponin test gave a falsely low result because of biotin interference.

Medication interactions

• Biotin can interact with certain medications, and some medications can have an adverse effect on biotin levels.

Possible side effects

• Some people taking large doses of pantothenic acid supplements develop mild diarrhea and gastrointestinal distress. The cause is not known.

Serious risks

• The FNB found no reports of pantothenic acid toxicity in humans at high intakes.

Medication interactions

• Pantothenic acid is not known to have clinically relevant interactions with medications.

Possible side effects

• High iodine intakes can cause goiter, elevated TSH levels, and hypothyroidism, some of the same symptoms as iodine deficiency.

Serious risks

• Iodine-induced hyperthyroidism can result from high iodine intakes, including when iodine is given to treat iodine deficiency.
• Studies have shown that excessive iodine intakes cause thyroiditis and thyroid papillary cancer.
• Acute iodine poisoning is rare and is usually caused by doses of many grams. Symptoms include burning of the mouth, throat, and stomach, fever, abdominal pain, nausea, vomiting, diarrhea, weak pulse, and coma.
• Long-term intakes above the UL increase the risk of adverse health effects.

Avoid or ask a doctor first if

• People with autoimmune thyroid disease or iodine deficiency may have adverse effects at iodine intakes considered safe for the general population.
• The ULs do not apply to people receiving iodine for medical treatment, who should be under a physician's care.

Medication interactions

• Iodine supplements have the potential to interact with several types of medications. People taking these medications on a regular basis should discuss their iodine intakes with their health care providers.

Possible side effects

• High doses from supplements or medications can cause diarrhea, nausea, and abdominal cramping.
• Magnesium carbonate, chloride, gluconate, and oxide are the forms most commonly reported to cause diarrhea.

Serious risks

• Very high doses can lead to magnesium toxicity, with low blood pressure, vomiting, difficulty breathing, irregular heartbeat, cardiac arrest and other signs.
• A few cases of fatal hypermagnesemia have been reported.
• Very large doses of magnesium-containing laxatives and antacids have been associated with magnesium toxicity.
• The risk of toxicity increases with impaired kidney function or kidney failure.

Avoid or ask a doctor first if

• People with impaired kidney function or kidney failure face higher risk of magnesium toxicity.
• People taking medications regularly should discuss their magnesium intake with their health care providers.

Medication interactions

• Magnesium may interact with oral bisphosphonates, tetracyclines, and quinolone antibiotics.
• Some medications, including diuretics and proton pump inhibitors, can affect magnesium status.

Serious risks

• Acute molybdenum toxicity is rare but can occur with industrial mining and metalworking exposure.
• In one study of high dietary molybdenum intake in an area of Armenia, affected people had achy joints, gout-like symptoms, and abnormally high blood uric acid.

Avoid or ask a doctor first if

• Infants up to 12 months should get molybdenum only from breast milk, formula, and food.

Medication interactions

• The source says molybdenum has no known, clinically relevant, interactions with medications.

Possible side effects

• Accidental swallowing of boric acid or borax, found in some household cleaners and pesticides, is linked to digestive, skin and nervous system symptoms.
• Boron toxicity can also cause headache, hypothermia, restlessness, and other symptoms.

Serious risks

• Extremely high doses of boron can be fatal in adults.
• In infants, high boron intakes have caused anemia, seizures, erythema, and thin hair.
• The upper limits are based on reproductive and developmental effects seen in animals.

Avoid or ask a doctor first if

• Infants should get boron only from breast milk, formula, and food.

Medication interactions

• Boron is not known to have any clinically relevant interactions with medications.

Possible side effects

• High zinc intakes can cause nausea, dizziness, headaches, gastric distress, vomiting, and loss of appetite.

Serious risks

• Doses of 50 mg or more taken for weeks can interfere with copper absorption, reduce immune function, and lower HDL cholesterol.
• Very high supplemental doses (142 mg/day) might interfere with magnesium absorption and disrupt magnesium balance.
• According to a few reports, overuse of zinc-containing denture adhesive creams can lead to neurological symptoms and anemia.

Avoid or ask a doctor first if

• The upper limits don't apply to people receiving zinc for medical treatment, who should be under a physician's care.
• Zinc-free denture adhesive formulations are available to prevent the effects linked to zinc-containing creams.

Medication interactions

• Zinc may interact with quinolone antibiotics, tetracycline antibiotics, and penicillamine.
• Some diuretics can lower serum zinc by increasing zinc excretion in urine.
• People taking medications regularly should discuss their zinc status with their health care providers.

Possible side effects

• Early signs of too much selenium are a garlic odor on the breath and a metallic taste in the mouth.
• Hair loss and nail brittleness or loss are the most common clinical signs of chronically high selenium intake.
• Other signs of chronically high intake include skin rash, nausea, diarrhea, fatigue, irritability, and nervous system abnormalities.

Serious risks

• Acute selenium toxicity can cause severe gastrointestinal and neurological symptoms, respiratory distress syndrome, heart attack, kidney failure, cardiac failure, and, in rare cases, death.
• Acute toxicity has resulted from misformulated over-the-counter products containing very large amounts of selenium. In 2008, 201 people had severe adverse reactions to a liquid supplement with 200 times the labeled amount.
• Brazil nuts contain very high amounts of selenium and could cause selenium toxicity if eaten regularly.

Avoid or ask a doctor first if

• The upper limits do not apply to people taking selenium under a physician's care.
• People who take medications regularly should discuss their selenium status with their health care providers.

Medication interactions

• Selenium supplements may interact with medications, and some medications, such as cisplatin, can affect selenium levels in the body.