By Barbara E. Amsler, MD
Vitamin B9 otherwise known as folate, folic acid or folacin, got its name from the Latin word folium, meaning “foliage”. It was discovered in 1931, as a cure for anemia and finally isolated in 1945, from spinach. Although it is found in many green leafy vegetables, it is easily destroyed by light, heat and an acid pH less than 4. In order to reduce the risk of deficiency, it is added back to many foods, in the USA.
Once consumed, folate is actively transported across the upper small intestinal wall into the blood stream. There it is converted to its active form (tetrahydrofolic acid) in the presence of niacin and vitamin C. It then circulates in the blood bound to a protein. About 6-9 months of it is stored in the liver and the rest is excreted in the urine and bile. Intestinal bacteria, if healthy, are capable of producing folate.
Folic acid and its derivatives are necessary for the production of DNA and RNA which are fundamental to the growth and replacement of every cell in the body. It is integral in the production of the brain’s neurotransmitters (chemicals that allow nerves to communicate). Similarly, folate helps the fetus’ brain and spinal cord to develop properly and prevents spina bifida. It aids in the production of hemoglobin (the oxygen carrying part of the red blood cell) and has been shown to reduce homocysteine levels. High levels of homocysteine have been linked to both atherosclerosis (by direct damage to the blood vessel wall) and osteoporosis (by affecting the protein matrix of bone).
Like the other B vitamins, toxicity is rare. However, people taking supplemental folate in the range of 10-15 mg daily, have had intestinal irregularity, fatigue, insomnia and irritability. Folate and vitamin B12 work together to make functional red blood cells and supplemental doses of folate may mask the symptoms of B12 deficiency.
Much more common is the risk of folate deficiency. Reduced dietary intake is frequently seen in the elderly, the poor and alcoholics. People suffering from diseases such as celiac sprue, gluten enteropathy, Crohn’s disease, resection of the upper part of the small intestine, gastric bypass, congestive heart failure, lymphoma, diabetic enteropathy or scleroderma may all have folate malabsorption. Furthermore, those with increased utilization of folate such as occur with pregnancy, cancer, inflammatory diseases, dermatitis, dialysis or liver disease may develop deficiency states.
Some medications like the anti-seizure drugs (dilantin, valproic acid, gabapentin, phenobarbital), estrogen, birth control pills, anti-inflammatories (aspirin and many other non-steroidal anti-inflammatories) and antibiotics (erythromycin, bactrim, tetracycline, neomycin, sulfasalazine) reduce the absorption or function of folic acid. Similarly, medications that neutralize stomach acid (Mylanta, Maalox, Omeprazole, Zantac, Pecid, etc) will inhibit the absorption of folate. Those taking diuretics (hydrochlorothiazide, lasix, furosemide, etc) will have enhanced excretion of folate and may become deficient after taking the diuretic for longer than 6 months. Diabetics on metformin may also develop both B12 and folate deficiencies. Additional intake of calcium may improve this.
The symptoms of folate deficiency include anemia, fatigue, weight loss, headache, diarrhea, memory problems, irritability, withdrawal, heart palpitations, decreased appetite and a sore, inflamed tongue. The recommended intake of 400 micrograms for men and women will prevent these symptoms. Unfortunately, 20% of Americans get less than half of this requirement. Women who are pregnant or breast feeding should take more, as the baby will drain their folate stores. Similarly, those taking any of the medications above or more than 2000 mg of vitamin C daily should increase their folate. People under physical or emotional stress will have a higher rate of cell turnover and also need more folic acid. Doses up to 1 mg daily have no toxic effects.
Folate deficiency can be diagnosed by either obtaining serum levels (blood folate) or red cell levels (tissue folate). Serum levels will decrease in accordance with the diet and may be abnormal months before symptoms begin. It indicates a negative folate balance and not an absolute deficiency. Conversely, the rbc folate level reflects the folate status at the time the red cell was made and is not subject to a recent decline in dietary intake. It does not fall below the normal range until all the body stores have been depleted.
Good food sources of folate include green leafy vegetables (spinach, kale, chard, asparagus, broccoli, cabbage), nuts (walnuts, filbert, peanuts, almonds, pecans), peas, beans, oatmeal, mushrooms, avocado, wheat bran, figs, blackberries and oranges.
Healthy Habits for Folate Intake:
1) The average multiple vitamin has 400 micrograms of folate. Supplemental forms of 1-15 mg are available by prescription. No toxicity has been reported in doses of 1 mg or less.
2) Women who are pregnant, breast feeding, taking birth control pills or on hormone therapy should take an additional 400 micrograms of folate.
3) People with congestive heart failure, high homocysteine levels or on diuretics should also take an additional 400 micrograms of folate.
4) Alcoholics or those who have 2 or more drinks daily should increase folate intake. Discuss this with your doctor for prescription doses of folate at 1-2 mg daily.
5) Because of the high rate of folate deficiency, anyone experiencing memory loss or declining mental function should try increasing folic acid.
6) People under physical or emotional stress or those with rapid cell turnover (cancer, arthritis, diarrhea, inflammatory diseases, infections, recent surgery, etc.) should also supplement folate.
7) As with previous B vitamins, anyone on prolonged antibiotic therapy should take extra folate and a probiotic.