The jury is still out on whether apple cider vinegar, which has been said to kill E. coli, reduce cholesterol, lower blood sugar and aid weight loss, is the cure for all ills, with experts saying while there are undoubted benefits, more research is still needed before they will be convinced of its powers.
In 2017, Darshna Yagnik, an immunologist and lecturer in biomedical science at Middlesex University, slugged back some apple cider vinegar (ACV) in efforts to ward off a potential case of food poisoning – and felt much better after half an hour, which is when she realised the ACV might possibly be having an effect on E. coli.
She decided to test it in the laboratory, and went on to do “a multitude of experiments” throughout the pandemic, resulting in a 2021 paper demonstrating that ACV kills E coli and MRSA in petri dishes almost as effectively as common antibiotics.
However, it is not clear how this would translate to the human body, reports The Guardian.
Nonetheless, this is one of the many promising results in recent studies into the benefits of ACV, now being touted by health influencers as a quick fix for gut health.
However, while research into some of the claims made for the fermented apple juice is promising, without large, robust clinical trials, medical staff can’t countenance recommending ACV.
Dietician Nichola Ludlam-Raine said although ACV has a reputation for aiding digestion, “there is no evidence supporting that”. But organic, unfiltered ACV is probiotic, as long as there is a brown, blobby fog called “the mother” floating around in it.
This, she said, “includes different proteins, enzymes and bacteria”.
“Some people believe this is responsible for the health benefits of apple cider vinegar, although there are no studies documenting this.”
ACV also contains 5% to 6% acetic acid, thought to play a key role in the health claims. Acetic acid is found in most fruits, which are also key sources of vitamins, minerals and fibre – unlike apple cider vinegar.
With Yagnik’s work, too, much more research is needed before the vinegar can be recommended officially for fighting pathogens, but what she has found so far is compelling.
“I started researching different ways the vinegar might be acting on the bacteria,” she said. “and it was amazing how it was working – it just destroyed them. Even my microbiologist friends were amazed.”
So far, it seems only to kill nasty bugs. “It has different effects on different microbes,” she said. “The effects seem to vary according to the microbe type, whether it is E coli or candida.”
Yagnik also doused white blood cells in ACV, and they were able to clear infections much faster than normal, “so it also seems to work on immunity”.
Her hypothesis may explain why so many people claim ACV makes them feel better in general (although this could be the placebo effect): “Vinegar that contains the mother has enzymes and antioxidants that support cell metabolism and function … It’s high in flavonoids and beneficial bacteria, which contribute to the human microbiome – vital for cellular immunity and defence.”
She suggests ACV has a two-pronged approach to fighting bugs: killing the bugs and strengthening our cellular defences. That said, the effects always depend on the individual, she says: “Everyone’s got a different immunity.”
While studying the effects on cells, she saw signs that ACV could help reduce inflammation, too. Again, this could be due to many components working together, from the enzymes to the flavonoids. “All of these in combination would optimise cells, boosting their function, and bring immune balance.”
The evidence on ACV controlling blood sugar is also intriguing. A 2019 meta-analysis of six small studies found that taking it daily resulted in lower fasting blood-glucose levels, as well as reduced cholesterol. A study in 2004 of people with insulin resistance or type 2 diabetes found that taking ACV after a high-carb meal reduced blood-sugar spikes (regular blood-sugar spikes and subsequent crashes are associated with chronic disease).
This means it could be helpful, alongside medication, in controlling blood sugar for people with type 2 diabetes.
At present, however, it is not medically recommended and could cause problems in blood-sugar control for people with type 1 diabetes.
The cholesterol finding from one of the blood-sugar studies is backed up by a meta-analysis of nine trials, which concludes that taking one tablespoon of ACV daily is most effective after doing so for eight weeks or more.
While the weight-loss studies are small and inconsistent, and give only a short-term picture, one found that, with two groups on a calorie-controlled diet for 12 weeks, the half that also took 30ml of vinegar daily lost on average 1.5kg more. Another found that overweight participants lost 1kg to 2kg over 12 weeks with no dietary restrictions.
But all of these results should be interpreted with caution.
“Drinking apple cider vinegar should not replace medicines for diabetes management and could be bad news for teeth health,” says Ludlam-Raine. “Apple cider vinegar is strongly acidic, so there are risks of enamel erosion – and reflux (heartburn), too.”
There have also been warnings that people with kidney disease or ulcers should avoid such acidity.
Ludlam-Raine says: “Evidence is minimal at present regarding appetite suppression and improving blood-sugar levels after a high-carb meal. You’re better off eating an apple (there’s more fibre, to keep gut bacteria happy, and it contains antioxidants, too).
“However, if you want to include AVC in your diet, use it in a salad dressing – alongside olive oil and black pepper – rather than drinking it.”
She concedes that much more research needs to be done; her own work continues. “There are so many different pathways that it’s acting on and it’s very exciting,” she says. “I think we’ve only scratched the surface.”
Study details
Antibacterial apple cider vinegar eradicates methicillin resistant Staphylococcus aureus and resistant Escherichia coli
DarshnaYagnik, Malcolm Ward & Ajit Shah.
Published in Nature Research in November 2021
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) and resistant Escherichia coli (rE.coli) infections can spread rapidly. Further they are associated with high morbidity and mortality from treatment failure. Therapy involves multiple rounds of ineffective antibiotics alongside unwanted side effects, alternative treatments are crucial.
Apple cider vinegar (ACV) is a natural, vegan product that has been shown to have powerful antimicrobial activity hence we investigated whether ACV could ameliorate these resistant bacteria. The minimum dilution of ACV required for growth inhibition was comparable for both bacteria (1/25 dilution of ACV liquid and ACV tablets at 200 µg/ml were effective against rE. coli and MRSA).
Monocyte co-culture with microbes alongside ACV resulted in an increase in monocyte phagocytosis by 21.2% and 33.5% compared to non-ACV treated but MRSA or rE. coli stimulated monocytes, respectively. Label free quantitative proteomic studies of microbial protein extracts demonstrated that ACV penetrated microbial cell membranes and organelles, altering the expression of key proteins.
This resulted in significant reductions in total protein expression, moreover we could only detect ribosomal proteins; 50 s 30 s, enolase, phosphenol pyruvate and the ATP synthase subunit in rE. coli. Elongation factor iNOS and phosphoglycerate kinase OS were the only proteins present in MRSA samples following ACV treatment.
See more from MedicalBrief archives:
Probiotics not always beneficial – US study
One beer daily could boost your gut microbiome – Portuguese study