Diet gun

Usually, excessive intake of vitamins is done from vitamin supplements and not from food and can lead to health complications.

The toxicity of most known vitamins when they accumulate in the body is mentioned below.

Vitamin A

Vitamin A (retinol) toxicity can be acute or chronic. Acute toxicity can be caused by accidental ingestion of 300,000 IU or more with symptoms such as headache, blurred vision, dizziness, nausea, vomiting, decreased motor coordination.

Chronic toxicity can occur with regular ingestion of more than 10,000 IU daily in supplement form. Symptoms of chronic hypervitaminosis A include vision loss, skin peeling, liver dysfunction, and intracranial hypertension.

Vitamin A supplementation >10,000 IU/day or >15,000 IU/day from combined food and supplement sources by pregnant women is associated with birth defects such as craniofacial malformations, central nervous system, heart, and limb anomalies.

Vitamin D

The human body produces 15,000–20,0000 IU of vitamin D with approximately 30 minutes of sun exposure.

Vitamin D (cholecalciferol) in doses up to 4000 IU/day is well tolerated.

Toxicity usually develops after taking very high doses 50,000–100,000 IU/day for at least 1 month.

Vitamin D toxicity causes high blood calcium that leads to kidney stones or damage, nausea, vomiting, weakness, dehydration, mental changes, calcification of organs like heart, lungs, kidneys.

Vitamin E

Vitamin E is related to the body’s antiplatelet activity and the increased risk of hemorrhagic stroke in excessive intake.

Vitamin E doses above 400 IU/day for one year have been associated with an increased risk of bleeding (mainly in people taking anticoagulants) and an increased risk of prostate cancer.

Vitamin K

Vitamin K toxicity is extremely rare, especially with natural forms (K1 and K2)..

It is not toxic in high doses orally in healthy people because the excess is excreted effectively or absorbed poorly by the body. Vitamin K3 is synthetic and not used in human supplements anymore because it can be toxic, especially in infants (over 10 mg/day) and in adults in high doses or injectable forms.

Vitamin B1

Vitamin B1 (thiamine) is extremely safe in high doses because it is rapidly excreted in the urine and has low absorption.

High intravenous doses of 500 mg or more can cause an allergic reaction (anaphylaxis) within minutes.

Oral administration of thiamine is very unlikely to cause toxicity.

Vitamin B2

Vitamin B2 (Riboflavin) is extremely safe in high doses because it is rapidly excreted in the urine and has low absorption even at doses above 1000 mg/day.

Vitamin B3

Moderate to high doses of vitamin B3 (niacin) 500 mg/day or more for more than 1 month are usually associated with peripheral vasodilation causing flushing of the skin, burning sensation, generalized itching and possible hypotension, lasting about 30 minutes and decreasing in severity and frequency over time.

At doses of 3-4.5 grams per day it can create cystoid macular edema in the eyes, blurred vision, eyelid swelling, loss of eyelashes or eyebrows.

At doses of more than 6 grams/day for a few days or 1 week it can create serious liver damage and glucose intolerance.

Vitamin B6

Vitamin B6 (pyridoxine) has been associated with severe peripheral neuropathy, most commonly at doses greater than 200 mg/day for 2 to 12 months, and at doses greater than 1000 mg/day for only a few weeks. The neuropathy may be irreversible.

Vitamin B9 – Folic acid

Folic acid at doses greater than 1 mg/day for months or 1 year may mask a possible B12 deficiency.

At doses of 5 mg – 15 mg/day for more than 1 year, it may cause abdominal cramps, diarrhea, flatulence, and a bitter taste in the mouth.

Vitamin B12

Excess B12 (Cobalamin) is excreted in urine, and absorption is self-limiting because only a small fraction is absorbed via active transport.

Even at therapeutic injectable doses of 5,000–10,000 mcg/day it is safe.

Vitamin C

Intake of vitamin C (ascorbic acid) supplement in doses as low as 250 mg/day can precipitate kidney stones from cysteine, uric acid, or oxalate in men predisposed to kidney stones.

Intake of 2,000–3,000 mg/day can cause mild gastrointestinal symptoms, while intake of more than 3,000 mg/day can cause immediate abdominal cramps and if this dose is continued for more than 1 month it will cause kidney stones.

Vitamin C in doses of 1,000–5,000 mg/day can directly reduce the effectiveness of antineoplastic drugs.