Everything you want to know about B vitamins

Executive Summary

There are at least eight different B–vitamins. They function in a similar way and are interdependent. They are found in the same food sources. Hence, they are grouped together.

B–vitamins are catalysts and cofactors in many body processes. They are vital for nerve function, cell production, immunity, energy production, and healthy pregnancy.

As one becomes older, one may develop vitamin B₆, B₉, and B₁₂ deficiencies. Vegetarian and vegan people are often severely deficient in B–vitamins. Read the full article below for many sources of B–vitamins, including vegan sources.

B–vitamins are linked to vascular integrity and can lead to medical conditions that involve blood vessel damage such as dementia, stroke, and heart disease.

It may not be worthwhile to test for deficiencies of various B–vitamins unless there is a specific medical reason or your doctor advises them. It is better to look at blood homocysteine levels, instead. Aim to keep it below 6.3 µmol/L.

B–vitamins are a group of water-soluble vitamins that are important for the metabolic activities of our body cells.

While they are chemically different compounds, they are often found in the same food sources. Also, their functions are similar or interdependent. Hence, they are grouped together as B-vitamins. Individually, they are named or numbered separately, such as folate or vitamin B₉.

Cofactors

Cell metabolism needs many enzymes and cofactors, which act as catalysts for the body’s processes and speed them up. In the absence of these catalysts, the processes progress very slowly, often by many orders of magnitude.

Let us say that a process takes 0.6 seconds to complete, with the help of catalysts. Without those catalysts, it may take 1,000 times more time. So, it will need 600 seconds, or 10 minutes, to complete. If a cell uses that process to generate energy, it will take 10 minutes for the cell to get any energy to work.

No wonder such a person will not be able to walk. From the time his brain tells his legs to start walking, it will be 10 minutes before they muster the energy to do so. This is a figurative example of how enzymes and cofactors, such as B–vitamins, work.

Some B–vitamins are not cofactors but are precursors, or raw materials, for such cofactors.

Members of the B–Vitamin Family

In literature, you will find a mention of more than twenty-five of B-vitamins. They were numbered from B₁ to B₂₀. Some others were named B_f, B_m, B_p, B_v, etc.

Now, for a chemical compound to be called a vitamin, it has to fulfill two criteria:

1. It should be required in the functioning of the body; and
2. The body should not be able to make it on its own.

It was found later that many of these twenty-five B–vitamins could be synthesized by the body. And some others were not required by the body, after all. So vitamins, such as B₄ and B₈, are no more B–vitamins.

Some B–vitamins are made by our body, but not by the bodies of some animal species. So they are B–vitamins for those animals, but not for us humans. That is, they are not vitamins in the first place for humans.

So, effectively, there are eight B–vitamins relevant for us, viz. from B₁ to B₁₂, except B₄, B₈, B₁₀, and B₁₁.

There are some claims by people that vitamin B₁₇ or amygdalin is able to prevent or cure cancer. But I could not find any good published studies to support those claims. Since this is a controversial matter, I would stay out of the debate and not consider it a B–vitamin for this article.

As an aside, vitamin D is not a vitamin either. It is synthesized by the body in the skin, on exposure to sunlight or ultraviolet rays.

Consumption of B–Vitamins

B–vitamins are water-soluble vitamins. So if you consume them in excess, they are excreted out of your body. As a result, their levels will rarely reach toxic levels in the body.

Your body cannot store B–vitamins, except vitamin B₁₂, for long periods of time. So, you need to regularly consume B–vitamins through foods.

Functions of B-Vitamins

Vitamin B₁ (Thiamine)

• Helps in nerve function
• Helps in energy production (carbohydrate breakdown to produce energy)
• Helps in cell growth

Vitamin B₂ (Riboflavin)

• Supports nervous system
• Helps in red blood cell production
• Helps in growth and development
• Helps in the use of other B–vitamins
• Helps the eyes and skin

Vitamin B₃ (Niacin)

• Produces cholesterol
• Helps in the use of other B–vitamins
• Essential in hormone production
• Helps skin
• Helps digestive system
• Helps nervous system

Vitamin B₅ (Pantothenic Acid)

• Helps in hormone production
• Helps in the use of other B–vitamins
• Helps in making cholesterol
• Helps in making red blood cells
• Helps in energy production (by the breakdown of carbohydrates and fats)

Vitamin B₆ (Pyridoxine)

• Helps in hormone production
• Helps in the production of red blood cells
• Helps digesting system
• Helps nervous system
• Helps immune system
• Helps in metabolising carbohydrates, proteins, and fats
• Helps in retaining proteins and carbohydrates as fuel
• Helps in enzymatic reactions
• Helps in making neurotransmitters
• Helps in making hemoglobin

Vitamin B₇ (Biotin)

• Helps store energy
• Helps metabolize carbohydrates, proteins, and fats
• Helps energy production
• Helps with hair, nail, and skin health
• Help product fatty acids

Vitamin B₉ (Folic Acid)

• Helps in the production of red blood cells
• Helps in female fertility and conception
• Helps in pregnancy, to prevent birth defects, such as spina bifida
• Helps in DNA creation

Vitamin B₁₂ (Cobalamin)

• Helps in the production of red blood cells
• Helps in DNA creation
• Helps immune system
• Helps nervous system
• Helps in protein metabolisation

RDIs of B–Vitamins

Daily Recommended dietary intakes or RDI of various B–vitamins are given in Table 1 below. There are different RDIs for men and women. Note that these are the new numbers for the USA.

In some special conditions, such as pregnancy, the numbers might be different. For example, in pregnancy, vitamin B₉ RDI is 600 µg and not 400 µg.

Also, note that the numbers are sometimes different for different countries. That is because a country’s government takes a call on those numbers, based on its ethnic composition. For reference, I have also mentioned RDI numbers for the Indian population as given by an Indian government agency.

The upper limit is the level above which harmful effects can be seen. Since B–vitamins are water-soluble, they are excreted out of the body in the urine. So, their upper limit level is not, or cannot be, established.

Read on this website, a comprehensive article on Recommended dietary intakes of various nutrients.

Table 1. RDIs of various B–vitamins in the USA and India

Vitamin	USA RDI (M)	US RDI (F)	India RDI	Upper limit
Vitamin B1	1.2 mg	1.1 mg	1.4 mg	Unknown
Vitamin B2	1.3 mg	1.1 mg	1.6 mg	Unknown
Vitamin B3	16 mg	14 mg	18 mg	35 mg
Vitamin B5	5 mg	5 mg	–	Unknown
Vitamin B6	1.7 mg	1.3 mg	2 mg	100 mg
Vitamin B7	30 μg	30 μg	–	Unknown
Vitamin B9	400 μg	400 μg	200 μg	1000 μg
Vitamin B12	2.5 μg	2.4 μg	1 μg	Unknown

Signs of B–Vitamins Deficiency

Deficiencies of different B–vitamins show signs specific to their shortfalls:

Vitamin B₆ Deficiency

• Anemia
• Mouth ulcers
• Chapped lips, cracks at the corner of the mouth
• Tingling, or numbness, in hands and feet
• Red, scaly, greasy, itchy, and inflamed skin, especially near oil-producing glands in the scalp, face, and chest
• Mood disorders, such as irritability, confusion, and depression

Vitamin B₉ (Folate or Folic Acid) Deficiency

1. Anemia
2. Mood disorders, such as irritability, confusion, and forgetfulness
3. Sore mouth
4. Diarrhea
5. In pregnancy, an increased risk of birth defects such as spina bifida

Vitamin B₁₂ Deficiency

1. Anemia
2. Tingling, or numbness, in hands and feet
3. Mood disorders, such as irritability, confusion, and forgetfulness
4. Poor muscle coordination, loss of balance

Sources of B-vitamins

Many foods contain some amount of nutrients. So when is a food item considered a good source of any nutrient? The rules of thumb for any food item to be called:

1. A good source of a nutrient: one serving of the food item must contain at least 10 to 19% of the recommended daily intake (RDI) of the nutrient.
2. High in a nutrient: one serving of the food item must contain at least 20% of the RDI of the nutrient.

Serving Size

Here is a simple rule for the size of a single serving:

• Fruits: 150 gm
• Vegetables: 75 gm
• Grains, nuts, seeds, legumes, beans, fish, egg, and meats: a quantity that gives about 120 calories

Read more about this: What is a serving size?

Now, just to make life more miserable, remember that this serving size is given by the Department of Health, Australia. They may be somewhat different in other countries.

Food Sources of B–Vitamins

• Vitamin B₁: Grains, port, tuna, and mussels
• Vitamin B₂: Mushrooms, almonds, dairy products, and chicken
• Vitamin B₃: Organ meats, beef, fish, chicken, eggs, dairy productions, and nuts
• Vitamin B₅: Leafy green vegetables, organ meats, meats, dairy products, legumes, and avocados
• Vitamin B₆: Liver, beef, white meat, fatty fish, potatoes, all non–citrus fruits
• Vitamin B₇: Beef, pork, sardines, egg yolks, whole grains, sweet potatoes, spinach, and broccoli
• Vitamin B₉: Leafy green vegetables, fatty fish, oranges, peanuts, asparagus, broccoli, and Brussels sprouts
• Vitamin B₁₂: Meats, eggs, and dairy products. There are no vegan sources, except nutritional yeast and Shitake mushroom

B–Vitamin Contents

I tried putting together a table of contents of various foods that are high in B–vitamins. But I gave up after some time when I found numbers all over the place. For example, two equally authentic sources claimed one large egg (50 g) contains 9% and 18% of RDI of vitamin B₁₂, respectively. So, look at the tables below as just rough numbers.

Vegan Sources

Table 2. Percentages of RDIs of various B–vitamins in vegan food sources

Food Item	Category	Serving	B1	B2	B3	B5	B6	B7	B9	B12
Black beans	Legumes	100 gm							38%
Chick peas	Legumes	100 gm							41%
Edamame	Legumes	100 gm							71%
Green peas	Legumes	100 gm							14%
Kidney beans	Legumes	100 gm							34%
Lentils	Legumes	100 gm							53%
Pinto beans	Legumes	100 gm							44%
Roasted soy nuts	Legumes	100 gm							52%
Collard greens	Vegetables	100 gm							24%
Romaine lettuce	Vegetables	100 gm							34%
Spinach, cooked	Vegetables	100 gm							36%
Spinach, raw	Vegetables	100 gm							48%
Turnip greens	Vegetables	100 gm							29%

Vegetarian, Non–Vegan Sources

Table 3. Percentages of RDIs of various B–vitamins in vegetarian, non–vegan food sources

Food Item	Category	Serving	B1	B2	B3	B5	B6	B7	B9	B12
Cheese, cheddar	Dairy	100 gm								33%
Milk	Dairy	250 ml	7%	26%		9%				18%
Yogurt, frozen, vanilla	Dairy	250 gm		30%						17%
Yogurt, plain	Dairy	250 gm		24%						39%
Yogurt, plain, greek	Dairy	250 gm		54%						82%
Yogurt, vanilla	Dairy	250 gm		52%						52%

Non-Vegetarian Sources

Table 4. Percentages of RDIs of various B–vitamins in non–vegetarian food sources

Food Item	Category	Serving	B1	B2	B3	B5	B6	B7	B9	B12
Egg, large (two)	Eggs	100 gm		30%		14%		66%	10%	18%
Salmon, cooked	Fish	100 gm	18%	29%	50%	19%	47%			51%
Tuna, canned	Fish	100 gm								92%
Beef	Meat	100 gm	5%	8%	39%	6%	31%			29%
Beef, grilled	Meat	100 gm								64%
Beef, liver	Meat	100 gm	12	201	87	69	51	138	65	1386%
Beef, liver, grilled	Meat	100 gm								3500%
Chicken, breast	Meat	100 gm		7%	69%	10%	30%			6%
Chicken, dark meat	Meat	100 gm		13%	33%	12%	18%			5%
Ham	Meat	100 gm								16%
Pork	Meat	100 gm	69%	24%	24%	9%	27%			14%
Turkey, breast	Meat	100 gm		8%	37%	7%	28%			7%
Turkey, dark meat	Meat	100 gm		15%	17%	14%	19%			7%
Blue mussels	Shellfish	100 gm	20%	25%	15%				19%	400%
Clams	Shellfish	100 gm	10%	25%	17%				7%	1648%
Oysters	Shellfish	100 gm	8%	26%	18%				4%	480%

Testing for Deficiencies

The biggest problem that arises with B–vitamins deficiency is high homocysteine levels. Read a comprehensive article on this website talking about that: Are B–vitamins and dementias related? The article explains the damage caused in the body by high homocysteine levels. It shows that the B–vitamin deficiency is the main cause of those high levels. So, it makes sense to test if you have a deficiency of any B–vitamin.

To check for B–vitamin deficiencies that can raise your heart and brain disorder risks, people do just their blood vitamin B₁₂ tests. There are three limitations in such blood vitamin B₁₂ checking:

• It does not tell you about vitamins B₆ and B₉ levels in the blood. Deficiencies of either can cause trouble, as mentioned above, even if vitamin B₁₂ levels are fine.
• Blood homocysteine levels may go up, even before vitamins B₆, B₉, or B₁₂ levels dip low enough to be flagged abnormal.
• Homocysteine levels can go high in kidney disease, underactive thyroid (hypothyroidism), or alcoholism. In such patients, levels of vitamins B₆, B₉, or B₁₂ may be normal.

Of course, if your doctor has advised you vitamin B₁₂ test, you should go with that advice. For example, your doctor may have advised you blood vitamin B₁₂ test to rule out pernicious anemia. That is a different disease category than what high homocysteine levels lead to.

However, if it is allowed in your country, and so, if you are going to check your vitamin B₁₂ levels for your own satisfaction, do consider a blood homocysteine test, instead. It is a common and relatively inexpensive test.

First published on: 19th June 2019
Image credit: Steve Buissinne from Pixabay
Last updated on: 23rd May 2022