Vitamin B complex: benefits and dosage 

Your body needs eight essential B vitamins for optimal health and brain function. Explore the benefits in this guide.

We all require a continuous flow of nutrients, and B vitamins are some of the most important for keeping our brains and bodies healthy.

While you can find B vitamins in many foods, Harvard Medical School warns that running low on your B vitamins can be a “ sneaky ” problem. Many people don’t get enough B vitamins from their food, especially if they follow a strict diet. For instance, up to 86.5% of vegetarians and vegans are low on vitamin B12, which is only found in animal-based foodstuffs.

Other people might consume the recommended B vitamins, but their bodies simply have a hard time absorbing them effectively.

Whether you’re trying to add more B vitamins to your daily meals, or you’re trying to figure out the source of your brain fog, the following supplement guide will outline everything you need to know about B vitamins, including:

  • The eight different types of B vitamins

  • The important roles that each B vitamin plays in your body and brain

  • How B vitamins support, enhance and strengthen your brain, your immune system and your general well-being

  • How much of each B vitamin you need every day, and how to hit those targets

  • What to look for in a B-complex vitamin supplement

The functions of each B vitamin

Blue background with pill box lying flat and pills coming out of it

There are eight specific B vitamins that you’ll want to focus on:

You can find all eight B vitamins in a B-complex supplement, but each vitamin has a distinct role to play:

Vitamin B benefits

You need various B vitamins for core processes like DNA formation, gene expression (the process by which your cells take action based on instructions from your DNA), and the production of blood cells. That’s how integral they are in every single process and system in your body.

Benefits of B vitamins on the body

B vitamins aren’t just good for your brain and cognitive function. They may also:

  • reduce the risk of cognitive decline and age-related illnesses reducing your homocysteine levels

  • boost your energy, in part by improving the cellular metabolic processes that convert food into energy and also by supporting the development of oxygen-rich red blood cells

  • help you achieve more balanced hormone health (for instance, 30% of people with thyroid problems are low in B12 )

  • help you to manage daily pressures, and have been shown to assist in balancing your endocrine system and cortisol levels

How much vitamin B complex do you need?

For optimal braincare and general wellness, aim for the following daily nutritional targets:

  • B1 (thiamine): 1mg

  • B2 (riboflavin): 1.3mg

  • B3 (niacin): 16.5mg

  • B5 (pantothenic acid): 6mg

  • B6 (pyridoxine): 1.2-1.4mg

  • B7 (biotin): 0.9mg

  • B9 (folic acid): 0.2mg

  • B12 (cobalamin): 0.002mg

Food sources for B vitamins

Citrus fruits as a food source for B vitamins

With the exception of vitamin B12, most B vitamins can be found in plant-based foods or fortified cereals and beverages.

Some of the best foods to add to your diet if you want to boost your intake of B vitamins include:

  • B1 (thiamine): citrus fruits, whole grains, liver and pork

  • B2 (riboflavin): dairy, eggs, leafy greens, and almonds

  • B3 (niacin): fatty fish, peanuts, avocado, and poultry

  • B5 (pantothenic acid): fatty fish, sweet potatoes, dairy and organ meats

  • B6 (pyridoxine): oats, bananas, peanuts, dairy and fish

  • B7 (biotin): leafy greens, peas, legumes, nuts and seeds, and salmon

  • B9 (folic acid): leafy greens, apples, corn, and many types of seafood

  • B12 (cobalamin): organ meats, beef, salmon, and fortified foods

Vitamin B complex supplements

If you aren’t getting enough of each B vitamin, or if you’re experiencing symptoms of a B-vitamin deficiency, consider taking a B-complex supplement. As its name suggests, a B-complex product provides all of the essential B vitamins you need without requiring you to take eight different supplements.

What other vitamins and minerals should I take with B vitamins?

Some supplements block the absorption of other nutrients, while others do the opposite and actually improve a specific nutrient's bioavailability. And don’t forget the importance of timing timing. Because B vitamins can be energising, take your B-complex vitamins in the morning to give yourself a physical and mental boost all day long.

FAQ about vitamin B supplements

1. What are vitamin B-complex supplements for?

B-complex vitamins protect the healthy functioning of your brain and body by:

  • Generating new red blood cells that carry nutrients and oxygen throughout your body

  • Lowering your homocysteine levels, which protects your blood vessels, your organs, your brain and other important systems

  • Supporting the production of neurotransmitters

  • Contributing to all cellular processes

2. Who should take a vitamin B-complex supplement?

Anyone who wants to proactively support their health from the cellular level on up will benefit from taking B vitamin supplements.

B-complex supplements may also be especially beneficial to people who are more prone to experience a B-vitamin deficiency, including:

  • Older people over the age of 50

  • Individuals who are pregnant or breastfeeding

  • Those on a strict diet that eliminates entire food groups, including those who are vegan, vegetarian, or keto

4. Is taking a B-complex supplement safe?

B vitamins are water-soluble, meaning your body flushes it out of your system when it has used up all the B vitamins it needs in a day. Research shows that most B vitamins are safe in high doses , with potential health drawbacks if you consistently take extremely large doses of B3, B6 or B9.

5. Can you overdose on a B-complex supplement?

Because B vitamins are water-soluble, you can’t overdose on B vitamins the way you would with a fat-soluble vitamin.

6. What are vitamin B-complex side effects?

Some people experience rare side effects of consuming too much of a specific vitamin B. Some side effects may include:

  • Increased urination

  • Excessive thirst

  • Nausea, cramping and gastrointestinal discomfort

  • Blurry vision

  • Skin conditions


Here's a handful of relevant scientific studies on B-complex supplementation:

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Sophie Medlin

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