What is the best way to increase Haemoglobin level?

Not really enough info to go but in a nutshelll – Find the cause of the low heamoglobin and correct it.

Iron, D3 and B12 is what I have heard, but I’m not a DR.

Eat a small amount of blueberries.

What you’re talking about is anemia. There are many causes of anemia. There may be a kydney problem which requires a specific pharmacological treatment. The bone marrow may not be producing new red blood cells, or there might be a deficiency in hemopoetic cells in the marrow. There’s a million reasons for anemia, each with a different specific therapy.

Most of these require prescription:
Carbonyl Iron
Cyanocobalamin
Ferrous Fumarate

There’s one relatively new drug that produces a lot of RBCs very quickly. It requires a weekly injection at a cost of about a grand a pop. They use it on cancer patients mostly, leukemia and Sickle Cell anemia victims. Serious stuff. Epoetin beta-methoxy poly blah blah blah. You might find some down at the racetracks. They illegally shoot up race horses with it sometimes. Makes ‘em run super fast and forever. Blood becomes packed with RBCs. Almost unlimited O2 to the muscles. High risk of stroke, but what the hell, as long as they win.

Or you could just take the old lady down to see a doctor.

Iron. Either iron supplements, and dark green leafy vegetables. Raisins have iron too, and they can help counteract the constipation from supplements. I recommend Slowfe iron, which you can but at the drugstore. Too much iron is a serious problem and very dangerous, so you should monitor your iron.

But, the only way you would know you have low numbers is if a doctor did a blood test, and you should check with your doctor about taking iron, and follow up with a blood test to see if everything is going in the right direction.