Hi all I just wanted to urge caution against attributing symptoms of breathlessness, fatigue and dizziness to low b12. I have low b12 and Vit D both of which can result in these symptoms. My breathlessness seemed to ease following b12 loading doses which I'd requested as a trial but didn't stay away for long. Thankfully GP had also referred me for an echocardiogram after noticing a murmur when examining me (I didn't think much of it as I had one when pregnant 15 years ago). The scan has picked up an undiagnosed ASD (hole in the heart) and I'm now waiting for another appointment with cardio to find out what happens next (most likely an op to repair). Please don't just assume these symptoms are all down to b12d as all the b12 injections in the world wouldn't have fixed this.