Is 1000 mg of B12 too much per day?
Even the lowest doses in B12 supplements are many times the recommended dietary allowance. Doses up to 1,000 mcg, though unnecessary, aren't harmful.
Left untreated, a vitamin B-12 deficiency can lead to anemia, fatigue, muscle weakness, intestinal problems, nerve damage and mood disturbances. The recommended daily amount of vitamin B-12 for adults is 2.4 micrograms.
It's common to start treatment for a significant vitamin B12 deficiency with weekly intramuscular shots (1000 micrograms of vitamin B12). This bypasses any absorption problems in the stomach or intestine, and is a good way to get an older person's vitamin B12 level back to normal quickly.
An abnormally high vitamin B12 status is anything over 900 pg/mL . This result may suggest liver or kidney problems, diabetes, or certain forms of leukemia.
The recommended daily amount for B12 is 2.4 mcg for adults. Pregnant and lactating women need higher amounts [1]. There is no upper intake limit for vitamin B12 because there is no known toxicity [2]. Most vitamin B12 supplements provide a range of strengths between 500 to 5,000 mcg [2].
Other side effects of vitamin B12 injections are more serious. Early on in treatment, these injections can cause pulmonary embolism (a blood clot that travels to one of your lungs from somewhere else in your body and blocks blood flow in the affected lung) and congestive heart failure.
Part of liver B12 is excreted in bile, and undergoes an enterohepatic circulation. The main causes of B12 malabsorption include inherited disorders (Intrinsic factor deficiency, Imerslund-Gräsbeck disease, Addison's pernicious anemia, obesity, bariatric surgery and gastrectomies.
Is taking high doses of B12 helpful or harmful? Since B12 is a water-soluble vitamin, it's generally considered safe, even at high doses. No Tolerable Upper Intake Level (UL) has been established for B12, due to its low level of toxicity.
How much vitamin B12 should you take? If your vitamin B12 levels are low, a common recommended OTC dose is about 1,000 mcg daily.
Dosages for Older People
When you're in your 60s you should officially start getting blood tests to test for vitamin B12 deficiency. Around this age, you should be getting around 2.4 micrograms of B12 a day.
Can too much B12 damage kidneys?
In diabetes patients with advanced kidney disease, high daily doses of B vitamins (folate, B6 and B12) were found in one study to worsen kidney function and double the risk of heart attack stroke and death (see the Cautions section of the B Vitamins Review for more information).
The usual dose for: diet-related deficiency is 50 micrograms to 150 micrograms, taken once a day. B12 deficiency not caused by your diet is one to two 1,000 microgram tablets, taken once or twice a day – this is usually if you cannot have vitamin B12 injections.
Make sure you have your levels checked. To much b-12 can aggravate the nerves.
1000 mcg is about 400 times as much as 2.4 mcg.
One large study found that women who took 1,000 mcg of vitamin B12, along with 2500 mcg of folic acid and 500 mg of vitamin B6 daily, reduced the risk of developing AMD, an eye disease that can cause loss of vision.
Supplementation with a highly bioavailable form of vitamin B12 5000 mcg is the most efficient way to ensure optimal levels. This is particularly important for vegans/vegetarians, the elderly, and anyone who is unable to absorb B12 efficiently.
This is particularly important if you experience any symptoms of high B12 levels in blood, including [9]: Gastrointestinal issues (like nausea, vomiting, and/or diarrhea) Headaches. Tingling in your hands and feet.
The common forms of vitamin B include vitamin B1 (thiamine), B2 (riboflavin), B3 (niacin), B6 (pyridoxine) and B12 (cyanocobalamin). Except for niacin (when given in high doses), there is no evidence that the other B vitamins, in physiologic or even super-physiologic high doses cause liver injury or jaundice.
Your doctor will give you the right dosage of vitamin B-12 supplement, especially if you will inject it. Taking too much can cause side effects like nausea, headache, dizziness, and in rarely, blood clots or cancer.
Summary: As summarized in the table provided, vitamin B12 (cobalamin) absorption and utilization by the body can be compromised with the chronic use of certain medications which include: colchicine, chloramphenicol, ethanol, histamine 2 receptor antagonists (H2RA), metformin, and proton pump inhibitors (PPI).
Does coffee affect B12 absorption?
Caffeine stimulates the production of stomach acid, which actually helps the body absorb B12. Caffeine may reduce the absorption of manganese, zinc and copper. It also increases the excretion of the minerals magnesium, potassium, sodium and phosphate.
There are other studies that found coffee drinkers tend to have higher hom*ocysteine levels which is a surrogate marker for b12 (and folate) deficiency. Overall it seems clear that coffee and caffeine increase excretion of B vitamins, including B 12.
In fact, 5000 mcg of Vitamin B12 supplementation is a safe dosing amount. Although, you do not need to consume that much. With the RDA at only 2.4 mcg for healthy adults, taking 5000 mcg just creates expensive urine. You can safely dose at lower levels and still reach the RDA.
A blood test showing a serum vitamin B12 level between 300 and 350 pg/mL is ideal for seniors, while anything between 200 and 900 pg/mL is considered normal. An elderly person should be getting 2.5 micrograms of B12 per day.
Cyanocobalamin injection
Once your vitamin B12 levels have stabilized, it's recommended to continue with 100 mcg once a month. But many healthcare providers follow a different dosing schedule for injectable vitamin B12. It's more common to inject 1,000 mcg (1 mL) once daily for 1 week.
References
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