Samantha Jenkins, 19, from Llanelli, fell into a coma and died in 2011.
Her inquest heard she had low mineral levels, which may have been the result of malabsorption caused by chewing gum.
Maria Morgan told BBC's Jason Mohammad programme: "It's something that happens over a period of time - eight or 10 months."
After her death, Mrs Morgan said she found receipts showing Miss Jenkins had been buying chewing gum almost every day.
"The pathologist said it was going down a road he doesn't know enough about, but he said there was enough evidence there to say it was a huge thing that it could be."
Her husband, Wayne Morgan, said they believed Miss Jenkins's death could be linked to sweeteners used in chewing gum.
Colin Phillips, acting senior coroner for Swansea, said the cause of death was a shortage of oxygen to her brain, resulting from a convulsion caused by an imbalance of minerals in her body.
"The chewing gum inside her system did not end her life, but it's a possibility the over consumption of sorbitol and aspartame was the result of all her salts going low and that's what ended her life," said Mrs Morgan.

PC Jonathan Adams part-owns a horse with a racing syndicate and on one of the occasions was seen celebrating a win on television, the panel heard.
He faces three allegations of gross misconduct under "honesty and integrity" but denies lying.
If proven he could be dismissed from Gloucestershire Police. The hearing continues.
The panel was told that in September 2015 and April 2016, the probationary police officer had reported in sick and went to Nottingham racecourse to watch the horse he part-owned, named Little Lady Katy.
In June 2016 he reported in sick again and went to Royal Ascot to watch Quiet Reflection, another horse owned by his syndicate, win the Commonwealth Cup.
The misconduct panel was shown a television clip of PC Adams jumping around and celebrating which had been shown on Channel 4 Racing.
PC Adams said he had acted to avoid a "toxic" environment at Barton Street station in Gloucester where he worked as an investigation officer.
He described suffering stomach cramps, migraines and being in an emotional place which was affecting his irritable bowel syndrome.
He told the hearing if he had gone into work instead of going to Ascot he "wouldn't have lasted" and would have been "sent home, not fit for duty".
Stephen Morley, presenting the case for the force, told the hearing: "It is not good enough to report in sick and go on a jolly.
"He is a public servant and he is obligated to do what he could for the public."
Barrister Richard Shepherd, representing PC Adams, said the officer was of "impeccable character" who "did his best" to manage the symptoms of a "stress-related" condition.
The hearing heard PC Adams transferred to Gloucestershire Police in 2014 from the Civil Nuclear Constabulary.
The mother of a Carmarthenshire teenager whose death may have been caused by chewing gum wants families to be aware of the potential dangers.
[NEXT_CONCEPT]
A police officer threw a "sickie" three times in order to watch horse racing, a misconduct hearing has been told.