Hello LaineyX75 and welcome to the forum. 

I'm sorry to hear about your brothers diagnosis. Unfortunately we're not able to suggest or recommend any brands of honey. It may be that other members who have used it see your post and are able to share their experiences. 
Alternatively you could chat to the team responsible for your brothers care who may be able to give you some advice and information. 

Best wishes, 
Jenn
Cancer Chat moderator

Dear Lainey, i'm sorry to hear about your brother's diagnosis, which must be a shock for you all. I work with cancer patients as a clinical nutrition consultant and unfortunately there is no evidence that Manuka honey helps GBM. If you are interested in evidence-based nutrition information for people with GBM, can I suggest you look at this information from a hospital in Liverpool, they are studying diets for people with brain cancers like GBM.

According to the latest research, sugar including honey would really not be a good idea for someone with a GBM diagnosis.

www.hra.nhs.uk/.../

There is an unanswered question about the natural antibiotic proprties of honey.

Most if not all honey's  contain chemicals from the plants the nector is taken from including hydrogen peroxide, the main chemical considered responsible for the natural antibiotic effect (although different honeys can contain different chemicals including some even more toxic).

The honey is then converted into the suger form/s the body uses including what glioblastoma can use. 

It is whether those sugars converted from honey then retain any of the antibiotic properties of the honey and reach & have a deliterous effect on the glioblastoma.

Manuka honey boasts a second chemical harvested with the manuka nector that when the peroxide is removed, manuka honey still retains antibiotic properties & in this GBM case, could that survive the gut, sugar conversion processes & passing the blood brain barrier to further mal effect the cancer.

I researched glioblastoma for a lot of hours but I couldn't find enough valid professional tests to support or disprove this theory & you have to be mindful of false vested interests in any such secondary / suppliment theory's but the NHS & Mayo say honey is OK so if you are a  hedge your bets person,  you could sway to honey as we did  in coffee when my wife was diagnosed with GBM & maybe Manuka honey as we swaped to later on when I heard about it. 

 I just thought it was healthier along with everything else but I do wonder how much difference ordinary honey or manuka honey really made  that is, did it do a lot more than I realised - she lived for 2 years after falling ill or 21 months from diagnosis & then died of covid-19 & at 12 months had had a 1/4 of the treatment she should have with an oncolgist hell bent of shoving her down the end of life path with cheap tricks & lies & only treated her properly from month 13 after he saw my complaints desperately trying to get her away from him & privately treated & then hid an edema & let it progress & ruined her health & too soon after covid-19 hit.

looking  back I question how much honey or manuka honey really helped as she did so well despite not having the proper treatment, so I'd love to see an extensive professional non vested interest test on honey.