L-Methylfolate 5-MTHF Capsules

Each capsule provides 1,000 mcg of folate as calcium L-methylfolate, which is 500% of the nutrient reference value. Take 1 capsule per day with food, as the label directs. A pot holds 60 capsules, a 60-day supply. The capsule contains the methylfolate with cellulose as the carrier in a vegetarian cellulose shell, no folic acid, and it is vegan.

Sources: Product label.

Methylfolate is folate in the form that makes up most of the folate circulating in blood. Its full name is 5-methyltetrahydrofolate, shortened to 5-MTHF. L-methylfolate, L-5-MTHF and calcium L-methylfolate all name the same compound; the last is its stable salt, the form that goes in a capsule. Folate is the family name for vitamin B9. Food folates, folic acid and folinic acid are the other members, and the body converts each of them into methylfolate before use.

Sources: NIH Office of Dietary Supplements; peer-reviewed review (PMC7760477).

Folic acid is the synthetic form used in fortified flour and most supplements. The liver must convert it in two enzyme steps, the second run by the MTHFR enzyme, before it becomes methylfolate, and methylfolate skips both. Comparative studies find the two raise blood folate at least equally well. A large share of people carry an MTHFR variant that slows the conversion, but NIH notes that standard folic acid still normalises homocysteine in people with the common variant. So the case for methylfolate rests on form, not on folic acid failing. For pregnancy, NHS advice names folic acid at 400 mcg a day, and a supplement does not change that advice.

Sources: NIH Office of Dietary Supplements; NHS; peer-reviewed review (PMC7760477).

Folate contributes to normal blood formation and to the normal function of the immune system. It also contributes to normal psychological function, to normal homocysteine metabolism and to the reduction of tiredness and fatigue. The vitamin has a role in the process of cell division and contributes to maternal tissue growth during pregnancy. Those are the functions the GB register of nutrition and health claims recognises. Underneath them is one job: supplying the single carbon units cells use to make DNA and to recycle homocysteine into methionine. A shortage therefore shows first in fast-dividing cells such as red blood cells.

Sources: GB register of nutrition and health claims; NIH Office of Dietary Supplements.

UK adults need 200 mcg of folate a day from all sources. NHS advice for anyone who could become pregnant is 400 mcg of folic acid a day until the twelfth week. One capsule at 1,000 mcg is five times the reference value. It also sits at the ceiling the European authority set for supplemental folate, 1,000 mcg a day, a ceiling set because high folate can hide a vitamin B12 deficiency. That is why this is a one-a-day capsule, not two. Anyone with unexplained tiredness or a low blood count should have B12 checked before starting it. The 5 mg dose used for high-risk pregnancies is a prescription, not a supplement.

Sources: Food Standards Scotland; NHS; EFSA; NIH Office of Dietary Supplements.

Any time of day, with food. Folate dissolves in water and is not stored in quantity, so a capsule a day matters more than the hour. Blood folate rises within a week or two of starting, because the serum level reflects the last few days of intake. Methylfolate raises it at least as fast as folic acid. Red cell folate averages the previous three to four months and takes that long to reflect the change, which is why a course for deficiency runs about four months. Anyone who started because of a low result should keep the retest date a GP has set.

Sources: NIH Office of Dietary Supplements; peer-reviewed review (PMC7760477).

Methylfolate is most often taken with vitamin B12, and the two are partners. Each is needed for the other to work in the cycle that recycles homocysteine. Taken together at ordinary doses they do not interfere, and a combined B12 and folate capsule is sold for that reason. The one rule is order: B12 is checked before folate is corrected. Folate can put the blood count right when the real problem is low B12, leaving that problem unseen. Prescription drugs are the interactions that matter: methotrexate works by blocking folate, and some antiepileptic drugs lower folate levels while folate can lower theirs in turn. Anyone on regular prescriptions should ask a pharmacist first.

Sources: NIH Office of Dietary Supplements; NICE.

Folate from food has no reported side effects, and supplements at up to 1 mg a day are unlikely to cause harm. The known risk of high folate is not a side effect but a mask. It corrects the anaemia of a vitamin B12 deficiency while the nerve damage carries on, which is why the B12 check comes first. Some people report feeling wired or restless on methylfolate. That comes from user reports rather than trials, and starting on alternate days is the usual answer. Anyone pregnant or planning to be should follow the NHS folic acid advice, and speak to a GP or midwife before using this capsule in its place. People on prescribed tablets should speak to a GP or pharmacist first.

Sources: Food Standards Scotland; NIH Office of Dietary Supplements; NHS.