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Can you take vitamin B complex and multivitamins together

Last reviewed by Editorial Team on September 5th, 2018.

B complex vitaimins and multivitamins basic facts

Vitamin B complex. The vitamin B-complex refers to all essential water-soluble vitamins excluding vitamin C that play important roles in cells metabolism.

These vitamins are: vitamin B1 (thiamine), vitamin B2 (riboflavin), vitamin B3 (niacin), vitamin B5 (pantothenic acid, vitamin B6 (pyridoxine), vitamin B7 or vitamin H (biotin), vitamin B9 (folic acid) and the cobalamins (vitamin B12).

Each vitamin of the B-complex has a unique chemical structure and has specific functions in the human body. Vitamins B1, B2, B3, and B7 have important role in energy production, vitamin B6 is essential vitamin for the metabolism of amino acids, and vitamin B12 and folic acid enable steps that are required for the division of cells.

However, each of these vitamins has many other functions. It is important to know that no functions require all B-complex vitamins simultaneously actions.

These preparations are used to provide B vitamins that are not taken enough through the diet or for treating vitamin deficiencies caused by different diseases.

Multivitamins are preparations containing multiple micronutrients, such as vitamins and dietary minerals. These preparations contain 3 or more vitamins and minerals at doses which are below the tolerable upper level, as determined by the Food and Drug Board, and they have no risk and adverse health effects.

Multivitamins do not contain drugs, herbs or hormones. These preparations are used to provide vitamins that are not taken enough by diet. They are also used to treat vitamin deficiencies caused by poor nutrition, pregnancy, illness, digestive disorders, and many other conditions.

Common commercial multivitamin supplement products usually contain the following ingredients: vitamins, B1, B2, B3, B6, B12, B5, vitamin C, folic acid, vitmains A, D, E, K, potassium iodide, zinc, calcium, manganese, magnesium, chromium, molybdenum, beta carotene, selenomethionine, and borates.

Other formulas may include additional ingredients such as lutein, lycopene, inositol, choline, PABA, trimethylglycine, vitamin K2, betaine, lecithin and higher amounts of B, C or E vitamins.

Vitamins can be used for the treatment of many health conditions such as: wound healing, canker sores, acne rosacea, alcohol withdrawal, anxiety, attention deficit hyperactivity disorder, hives, osteoporosis, indigestion, heartburn, low stomach acidity, vitiligo, anemia and other conditions.

How does vitamin B complex and multivitamins work in the body

Vitamin B1 Thiamine has a central role in the production of energy from carbohydrates. It is also involved in RNA and DNA production and neurons function. Coenzyme called thiamine pyrophosphate (TPP) is thiamin’s active form which takes a significant part in metabolism.

Vitamin B2 – Riboflavin is important in the production of energy in electron transport chain, in the citric acid cycle and the catabolism of fatty acids.

Vitamin B3 – Niacin is composed of 2 structures: nicotinamide and nicotinic acid. Niacin has two co-enzyme forms: NAD – nicotinamide adenine dinucleotide and NADP – nicotinamide adenine dinucleotide phosphate. Both has important role in energy transfer in the metabolism of glucose, fats and alcohol.

Vitamin B5 – Pantothenic acid has important role in fatty acids and carbohydrates oxidation processes. Coenzyme A is formed from pantothenic acid, and it is involved in the synthesis reactions of many compounds in the body.

Vitamin B6 – composed of 3 structures: pyridoxine, pyridoxal, pyridoxamine. The active form pyridoxal 5′-phosphate is a cofactor in many enzyme reactions such as amino acid metabolism that includes neurotransmitters biosynthesis.

Vitamin B7- Biotin is important in the metabolism of lipids, proteins and carbohydrates.

Vitamin B9 – Folic acid is involved in the transfer of single-carbon units in the anabolism of nucleic and amino acids. It is needed for normal cell division, during pregnancy and infancy, and for rapid growth processes. Folic acids also has important role in erythropoiesis – the production of red blood cells.

Vitamin B12 – cobalamins is involved in the cell metabolism of carbohydrates, proteins and lipids. It is very important in production of blood cells in bone marrow, and also for proteins and nerve sheaths production.

Vitamin C is very significant for bones and connective tissues, muscles, and blood vessels. Vitamin C also helps the body to absorb iron. Vitamin C may also act as a very potent antioxidant against oxidative stress.

Vitamin A is important for the normal function of eyes, skin, and for normal growth. Body uses vitamin A for gene transcription, immune cell functioning, embryonic development and reproduction, bone metabolism and as an antioxidant.

Vitamin D has important role in bone and homeostasis of calcium homeostasis.

Vitamin K has a key role in blood clothing and preventing excessive bleeding.

Vitamin E is important for strong immunity and healthy eyes and skin. It also has antioxidant properties.

Can patients take vitamin B complex and multivitamins together

Taking vitamins on a daily basis is a healthy habit, however, if patients are taking vitamins in amounts that are more than they need, this can be trouble, especially for a liver and gastrointestinal health. So, patient should always consult their doctors first and check nutrition facts labels, before they take any Vitamin B complex and multivitamins together.

Many multivitamins contain appropriate amounts of B vitamins, but there are many preparations that can contain higher doses of certain B vitamins. If such preparations are taken together with vitamin B complex there is a high probability of exceeding high upper levels for any of the B vitamins.

Too much of certain B vitamins, can cause toxicity symptoms such as: increased risk of heart disease, stroke, stomach ulcers and liver damage.

Niacin and vitamin B-6 are two B-vitamins that have toxicity concerns. By taking both, a B-complex vitamin and a multivitamin, tolerable upper intake level for niacin can be exceeded. The recommended dietary allowance for vitamin B-6 for adults is 1.3 mg, compared to an upper limit of 100mg.

The recommended dietary allowance for niacin, however, is 16 mg daily for men and 14 milligrams daily for women, and the upper limit for adults is only 35 mg daily.

Thus, taking two different supplements that each contains the recommended dietary allowance will put patients almost at the limit, without counting niacin that patient may take from food. Niacin overdose can cause vomiting, nausea, liver problems, blurred vision, and high-blood sugar.

The table below shows the recommended daily intake of vitamins and over dosage side effects:


Recommended daily intake

Over dosage

(mg or µg/d)

30 µg No information
400 µg Anemia, vitamin B12 deficiency symptoms masking
Vitamin A 600 µg Loss of appetite, dry skin, fatigue, nausea, bone and joint pains and headaches
Vitamin B1 (thiamin) 1,4 mg No toxic effects have been observed
Vitamin B2 (riboflavin) 1,6 mg Urine colour alteration
Vitamin B3 (niacin) 18 mg Facial flushing, liver disease
Vitamin B5 (patothenic acid) 6 mg Nausea and heartburn
Vitamin B6 (pyridoxine) 2 mg Numbness and tingling in hands and feet
Vitamin B12 (cobalamine) 6 µg Eye conditions
Vitamin C (ascorbic acid) 75 mg No toxic effects have been observed
Vitamin D (cholecalciferol) 5 µg Eating problems, disorientation, coma and death
Vitamin E (tocopherol) 10 mg Blood clotting, haemorrhage
Vitamin K 80 µg Liver damage or anaemia

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