How to lower homocysteine

The table ranks the levers by effect size from controlled studies. The supplement trials report percent or absolute change against placebo; diet studies compare a full diet with a control diet.

How much you lower depends on where you start. Folic acid gives bigger drops when homocysteine is higher and folate lower to begin with, and the effect is larger in women than in men [1][7]. In people who already eat folic-acid-fortified food, the room to lower is smaller [8].

The bar chart puts the main absolute changes side by side: folic acid plus B12 lowered homocysteine by 3.8 µmol/L in SEARCH [9] and HOPE-2 lowered it by 3.2 µmol/L against placebo [10]; riboflavin lowered it by 3.6 µmol/L in TT carriers [2]; folic acid 0.8 mg and betaine 6 g lowered it by 2.7 and 1.8 µmol/L [11]; and coffee raised it by 1.5 µmol/L [5].

The Homocysteine Lowering Trialists' Collaboration pooled individual data from 25 trials and 2,596 people. Standardised to a starting homocysteine of 12 µmol/L, daily folic acid lowered it by 13% at 0.2 mg, 20% at 0.4 mg, 23% at 0.8 mg, 23% at 2 mg and 25% at 5 mg [1]. The authors concluded that 0.8 mg or more is typically needed for the maximal effect.

Higher doses add little to homocysteine and are less studied for safety. A 2026 meta-analysis of 36 trials in people with hyperhomocysteinemia found larger drops at 5 to 15 mg a day, but the trials were small and biased, none measured heart attacks or strokes, and the three studies at 15 mg a day reported more cardiovascular events [12].

Folic acid can also mask the anaemia of B12 deficiency, so clinicians usually check B12 before high doses. Dose decisions belong with a clinician.

B12 is the cofactor for methionine synthase. Added to folic acid at 0.4 mg a day it lowered homocysteine by a further 7% [1]; the earlier pooled analysis gave a similar 7% for about 0.5 mg [7]. When B12 is actually deficient, the effect is larger: metformin users who became B12 deficient averaged 23.7 µmol/L, against 14.9 µmol/L in those with normal B12 [13].

People most likely to benefit from B12 are those with a reason to be low: long-term metformin [13], vegan or vegetarian diets without supplements [14] and older age. A whole-food plant-based diet keeps B12 on its checklist for this reason.

Vitamin B6 is needed for the transsulfuration exit, but it did not significantly lower fasting homocysteine when added to folic acid [1][7]. In NORVIT, the group given B6 with folic acid and B12 trended toward more cardiovascular events (RR 1.22) [15], so high-dose B6 offers no clear advantage.

Diet. In a controlled feeding study, a DASH-style diet rich in fruit, vegetables and low-fat dairy lowered homocysteine by about 0.8 µmol/L compared with a typical American diet, and the change tracked a rise in serum folate [4]. Folate-rich foods include leafy greens, legumes and fortified grains; B12 comes from animal foods or fortified foods and supplements [14]. The Mediterranean diet and MIND diet both emphasise these foods.

Betaine (trimethylglycine) remethylates homocysteine through a separate liver enzyme. Six grams a day lowered fasting homocysteine by 1.8 µmol/L [11], and five trials of 4 g or more gave 1.23 µmol/L [3]. Beets, spinach and whole grains contain betaine.

Riboflavin (vitamin B2) stabilises the MTHFR enzyme. At 1.6 mg a day for 12 weeks, it lowered homocysteine from 16.1 to 12.5 µmol/L in people with the TT genotype, and had no effect in CC or CT carriers [2].

In a randomised crossover trial, drinking 1 litre a day of paper-filtered coffee for 4 weeks raised fasting homocysteine from 8.1 to 9.6 µmol/L, an 18% increase, in 24 of 26 volunteers, without changing B-vitamin levels [5]. Ordinary intakes have smaller effects.

In the Hordaland study of 16,176 adults, homocysteine rose with the number of cigarettes smoked per day, especially in women, and heavy-smoking older men averaged 4.8 µmol/L more than young non-smoking women [16]. These are observational differences; there is no trial of quitting and homocysteine, but quitting has many other benefits.

Physical activity was linked to lower homocysteine and higher blood pressure and cholesterol to higher levels in the same population [16][17].

Betaine and folic acid lowered homocysteine within 6 weeks [11], and riboflavin within 12 weeks [2]. The betaine meta-analysis included trials of 6 to 24 weeks [3]. In the big outcome trials, the reduction lasted: SEARCH held a 28% reduction for 6.7 years [9] and HOPE-2 for an average of 5 years [10].

If you retest, use the same conditions as the first test, ideally fasting and with prompt processing, because single values vary by about 8% [18]. See the homocysteine test for preparation.

• Heart attack and death: no benefit. Across 15 trials and 71,422 people, heart attack risk was RR 1.02 and death RR 1.01 [6]. Eight large trials pooled gave RR 1.01 for major vascular events [19].
• Stroke: small benefit. The same Cochrane review found stroke RR 0.90 [6]. In low-folate China, folic acid plus enalapril cut first stroke from 3.4% to 2.7% (HR 0.79) [20].
• Brain: promising but unproven for dementia. In VITACOG, B vitamins slowed brain atrophy from 1.08% to 0.76% a year and by 53% in people above 13 µmol/L [21], but pooled effects on global cognition are very small [22].
• B12 deficiency: real benefit. Treating true deficiency prevents anaemia and nerve damage, and homocysteine is one way to monitor it [23][24].

So the strongest reason to lower homocysteine is to correct a deficiency. Using B vitamins mainly to prevent heart disease is not supported. Talk to a clinician before starting high-dose supplements, especially with kidney disease, after a heart event or on medication.