If you find that methylcobalamin helps, especially with brain fog, fatigue, and other related issues, it's likely that your homocysteine was high. Methyl-B-12 lowers homocysteine.

Homocysteine is often high in mercury toxic persons because mercury blocks the methylation of B-12, which is why it's important to buy a pre-methylated type.

Elevated homocysteine over a long period will increase the risk of heart disease and raise cholesterol considerably.

Methyl-B-12 is also in the chemical pathway of glutathione, which is the body's natural defense against mercury.

So, mercury blocks the very process that enables the body to eliminate it—the methylation of B-12. Another reason that mercury is so dangerous.