Linus Pauling Institute: Micronutrients for Depression

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Sun, 7 Nov 2004 12:01:52 -0500

Subject:[sSRI-Research] Linus Pauling Institute: Micronutrients for

Depression

 

Depression

 

http://lpi.oregonstate.edu/infocenter/vitamins/vitaminB12/index.html#depression

 

Observational studies have found as many as 30% of patients

hospitalized for depression to be deficient in vitamin B12 (19). A

recent cross-sectional study of 700 community-living, physically

disabled women over the age of 65 found that vitamin B12 deficient

women were twice as likely to be severely depressed as non-deficient

women (20). The reasons for the relationship between vitamin B12

deficiency and depression are not clear. Vitamin B12 and folate are

required for the synthesis of S-adenosylmethionine, a methyl group

donor essential for the metabolism of neurotransmitters, whose

bioavailability has been related to depression. Because few studies

have examined the relationship of vitamin B12 status and the

development of depression over time, it cannot yet be determined if

vitamin B12 deficiency plays a causal role in depression. However, due

to the high prevalence of vitamin B12 deficiency in older individuals,

it may be beneficial to screen them for vitamin B12 deficiency as part

of a medical evaluation for depression.

 

SOURCES

 

Food sources

 

Only bacteria can synthesize vitamin B12. Vitamin B12 is present in

animal products such as meat, poultry, fish (including shellfish), and

to a lesser extent milk, but it is not generally present in plant

products or yeast (1). Fresh pasteurized milk contains 0.9 mcg per cup

and is an important source of vitamin B12 for some vegetarians (5).

Those vegetarians who eat no animal products need supplemental vitamin

B12 to meet their requirements. Also, individuals over the age of 50

should obtain their vitamin B12 in supplements or fortified foods like

fortified cereal because of the increased likelihood of food-bound

vitamin B12 malabsorption.

 

Most people do not have a problem obtaining the RDA of 2.4 mcg/day of

vitamin B12 in food. In the United States, the average intake of

vitamin B12 is about 4.5 mcg/day for young adult men, and 3 mcg/day

for young adult women. In a sample of adults over the age of 60, men

were found to have an average dietary intake of 3.4 mcg/day and women

2.6 mcg/day (5). Some foods with substantial amounts of vitamin B12

are listed in the table below along with their vitamin B12 content in

micrograms (mcg). For more information on the nutrient content of

foods you eat frequently, search the USDA food composition database.

 

Food Serving Vitamin B12 (mcg)

Clams (steamed) 3 ounces 84.0

Mussels (steamed) 3 ounces 20.4

Crab (steamed) 3 ounces 8.8

Salmon (baked) 3 ounces* 2.4

Rockfish (baked) 3 ounces 1.0

Beef (cooked) 3 ounces 2.1

Chicken (roasted) 3 ounces 0.3

Turkey (roasted) 3 ounces 0.3

Egg (poached) 1 large 0.4

Milk 8 ounces 0.9

Brie (cheese) 1 ounce 0.5

 

*A three-ounce serving of meat or fish is about the size of a deck of

cards.

 

Supplements

 

Cyanocobalamin is the principal form of vitamin B12 used in

supplements but methylcobalamin is also available. Cyanocobalalmin is

available by prescription in an injectable form and as a nasal gel for

the treatment of pernicious anemia. Over the counter preparations

containing cyanocobalamin include multivitamin, vitamin B-complex, and

vitamin B12 supplements (21).

 

SAFETY

 

Toxicity

 

No toxic or adverse effects have been associated with large intakes of

vitamin B12 from food or supplements in healthy people. Doses as high

as 1 mg (1000 mcg) daily by mouth or 1 mg monthly by intramuscular

(IM) injection have been used to treat pernicious anemia, without

significant side effects. When high doses of vitamin B12 are given

orally only a small percentage can be absorbed, which may explain its

low toxicity. Because of the low toxicity of vitamin B12, no tolerable

upper intake level (UL) was set by the Food and Nutrition Board in

1998 when the RDA was revised (5).

 

Drug interactions

 

A number of drugs reduce the absorption of vitamin B12. Proton pump

inhibitors (e.g., omeprazole and lansoprazole), used for therapy of

Zollinger-Ellison syndrome and gastroesophageal reflux disease (GERD),

markedly decrease stomach acid secretion required for the release of

vitamin B12 from food but not supplements. Long-term use of proton

pump inhibitors has been found to decrease blood vitamin B12 levels.

However, vitamin B12 deficiency does not generally develop until after

at least three years of continuous therapy (22). Another class of

gastric acid inhibitors known as H2-receptor antagonists (e.g.,

Tagamet, Pepsid, Zantac), often used to treat peptic ulcer disease,

has also been found to decrease the absorption of vitamin B12 from

food. Because inhibition of gastric acid secretion is not as prolonged

as with proton pump inhibitors H2-receptor antagonists have not been

found to cause overt vitamin B12 deficiency even after long-term use

(23). Individuals taking drugs that inhibit gastric acid secretion

should consider taking vitamin B12 in the form of a supplement,

because gastric acid is not required for its absorption. Other drugs

found to inhibit the absorption of vitamin B12 from food include

cholestyramine (a bile acid-binding resin used in the treatment of

high cholesterol), chloramphenicol, neomycin (antibiotics), and

colchicine (anti-gout). Metformin, a medication for individuals with

type 2 (non-insulin dependent) diabetes, decreases vitamin B12

absorption by tying up free calcium required for absorption of the IF-

B12 complex. This effect is correctable by drinking milk or taking

calcium carbonate tablets along with food or supplements (4). Previous

reports that megadoses of vitamin C resulted in the destruction of

vitamin B12 have not been supported (24) and may have been an artifact

of the assay used to measure vitamin B12 levels (5).

 

Nitrous oxide, a commonly used anesthetic inhibits both vitamin B12

dependent enzymes and can produce many of the clinical features of

vitamin B12 deficiency, such as megaloblastic anemia or neuropathy.

Because nitrous oxide is commonly used for surgery in the elderly,

some experts feel vitamin B12 deficiency should be ruled out prior to

its use (3, 7).

 

Large doses of folic acid given to an individual with an undiagnosed

vitamin B12 deficiency could correct megaloblastic anemia without

correcting the underlying vitamin B12 deficiency, leaving the

individual at risk of developing irreversible neurologic damage (5).

For this reason the Food and Nutrition Board of the Institute of

Medicine advises that all adults limit their intake of folic acid

(supplements and fortification) to 1000 mcg (1 mg) daily.

 

LINUS PAULING INSTITUTE RECOMMENDATION

 

A varied diet should provide enough vitamin B12 to prevent deficiency

in most individuals 50 years of age and younger. Individuals over the

age of 50, strict vegetarians, and women planning to become pregnant

should take a multivitamin tablet daily or eat a fortified breakfast

cereal, which would ensure a daily intake of 6 to 30 mcg of vitamin

B12 in a form that is easily absorbed.

 

Older adults (65 years and over)

 

Because vitamin B12 malabsorption and vitamin B12 deficiency are more

common in older adults, some respected nutritionists recommend 100 to

400 mcg/day of supplemental vitamin B12, an amount provided by a

number of vitamin B-complex supplements. Vitamin B12 injections are

not necessary unless an individual has been diagnosed with pernicious

anemia.

 

 

 

 

[Guest guest]

I recently started taking a high-potency sublingual B12 supplement two

weeks ago which one is supposed to let melt under the tongue so that the

B12 can get directly into the bloodstream without having to go through

the digestive system. It is a formula patented by Dr. Alfred Libby,

who, judging from the info I was sent with the product, is an

orthomolecular doctor in the same league as Linus Pauling--or at least

that was the impression I got. (Moderator's Note: Pauling was a world class

scientist and was the recipient of two unshared Nobel prizes.)

 

I am taking it for depression and low energy. I have noticed some small

changes already, such as feeling less lethargic and " hung over " when I

wake up in the morning. But it is supposed to take 30 days before one

feels the full effect of the product. The product also contains B6 and

Folic Acid.

 

Cathy B.

 

>Supplements

 

>Cyanocobalamin is the principal form of

> vitamin B12 used in

>supplements but methylcobalamin is also

> available. Cyanocobalalmin is

>available by prescription in an injectable

> form and as a nasal gel for

>the treatment of pernicious anemia. Over

> the counter preparations

>containing cyanocobalamin include

> multivitamin, vitamin B-complex, and

>vitamin B12 supplements (21).