Move aside coconut oil, your time in the superfood spotlight has passed. Today it is apple cider vinegar, the latest all-natural, all wholesome, all singing, all dancing superfood that's here to save you from just about anything that ails you. With claims ranging from sterilising toothbrushes, curing diabetes and melting away waistlines, in this podcast I’ll look behind the apple cider trend to see what the science has to say.
Apple cider vinegar is one of the latest additions to the superfood revolving door family. But there is nothing new under the sun about apple cider vinegar – it's been around as an ingredient in folk medicine for centuries.
Let’s take a step back first and talk about vinegar in general, which is just a fairly dilute form of good old acetic acid. Vinegar is made by fermentation of alcohol or sugar by acetic acid bacteria with the flavouring of it coming from the source from which the vinegar is made which can be just about any type of fruit or grain.
Apple cider vinegar is made from fermented apples which are first chopped up, covered with water and left until the natural sugar ferments and forms ethanol. The second stage is when bacteria converts the alcohol into acetic acid and there you have it – apple cider vinegar. There really is nothing that special about this process as it can be repeated with hundreds of different types of foods.
Apple cider vinegar has a distinctive cloudy-brown colour due to it being unstrained and containing strands of material often called "the mother", which is a mixture of proteins, yeast and bacteria that look a bit like cobwebs floating in the liquid. Many people attribute apple cider vinegar’s effects to the "mother." And there’s some truth to this since the mother counts as a probiotic. But, the importance of the mother has not been established with research so there is really zero to say about it at this time.
So, if we left the story here, it would just be a nice tale about a condiment you may care to keep in your pantry. But enter the Internet… Do a Google search for apple cider vinegar and you’ll find all sorts of amazing health claims: from cutting your risk of cancer to even getting rid of dandruff. But the most common claims centre around its benefit for weight loss and controlling blood sugars. So, let’s delve into those ones and spoiler alert: they are the only ones that have even a skerig of science behind them.
Weight
The claims that a shot of ACV will melt away body fat does have a small amount of scientific evidence behind it - coming from two human clinical trials. A 2009 study from Japan showed that a group of overweight men and women who took two tablespoons of ACV each day for 12 weeks did see a small benefit on body weight of just under 2 kilograms and waist circumference and blood triglycerides fell too compared to people who weren’t drinking ACV. I’ll link to the study in the show notes https://www.jstage.jst.go.jp/article/bbb/73/8/73_90231/_article
A more recent study randomly assigned 39 people to follow a restricted-calorie diet with or without apple cider vinegar for 12 weeks. While both groups lost weight, the apple cider vinegar group did lose a bit more, by a bit under 2 kilograms. And I’ll link to this study in the show notes https://www.sciencedirect.com/science/article/abs/pii/S1756464618300483
These two studies are certainly interesting, but was it thanks to the metabolic miracle that is ACV? Most likely no as there have been several taste studies done finding that drinking vinegar, in general, can induce a slight feeling of nausea and a lessening of appetite in some people which is hardly surprising. That does not in any way negate that apple cider vinegar may have a small benefit on weight loss, but the mechanism here is probably making a person feel a little ill and reducing their appetite. You can drink plain old private label supermarket vinegar and get the same results if you want. There could though be a benefit for weight loss by regulating blood sugar levels which is an interesting area I’ll explore next.
Blood sugars
Another claim that is hard to miss is that apple cider vinegar will reduce blood sugar and insulin levels. This is a rare situation where there actually is some reasonable evidence to support the claim, but spoiler alert: it is nothing miraculous to do with apple cider vinegar – it’s related to the acetic acid, for which any vinegar will do the trick.
Way back in 1987, Japanese researchers found that giving a small group of healthy volunteers vinegar containing 5 per cent acetic acid could blunt the rise in blood glucose after having a dose of sucrose on an empty stomach. https://www.tandfonline.com/doi/abs/10.1080/00021369.1988.10868833 Likewise, another small study in 2005 found that different levels of acetic acid could also blunt blood glucose and insulin responses in healthy volunteers after a meal of white bread while also increasing the feeling of fullness. https://www.nature.com/articles/1602197
There have been other studies in this area too, and the sum of the findings were included in a meta-analysis published in 2017 which I’ll link to in the show notes. And the conclusion? The pooled analysis of studies revealed a significant reduction in glucose and insulin in people who consumed vinegar compared with a control group. Note here though that there is no mention of apple cider vinegar? It is just generic vinegar that it relates to, which of course ACV falls under because of its acetic acid content. https://pubmed.ncbi.nlm.nih.gov/28292654
Most of the research in this area has been with healthy volunteers, but there have been some small studies in people with type 2 diabetes which is of interest and the research seems to show a benefit, but by not as much as that seen in people with normal glucose responses. If you want to dig more into this research, I’ll link to a review paper in the show notes on this topic and which also delves into the potential mechanisms for why vinegar may be beneficial. Vinegar may help mediate the production of hormones involved in glucose regulation, reduce the activity of carbohydrate digesting enzymes, improve insulin sensitivity and even increase blood flow to tissues. But a key point in that the benefit of vinegar seems to mostly apply to meals that contain starch, it will do very little for high-fat meals. https://pubmed.ncbi.nlm.nih.gov/27213723
So, does this mean everyone should be drinking vinegar shots with their meals? No. If you don’t have diabetes, then your blood glucose is being regulated just fine. But if you do have type 2 diabetes, there likely is not as great a benefit as the underlying condition is already a symptom of impaired glucose regulation and insulin resistance so vinegar can’t overcome all of that. But you absolutely must talk to your doctor if you are considering this approach especially if you are taking medications to help treat diabetes.
Other claims
What about all those other health claims you may have read about for apple cider vinegar? Just about all of them are not supported by much evidence nor is there any strong reason why apple cider vinegar should even give these benefits over and above any other type of mild acid.
Because of apple cider vinegar's antimicrobial properties (albeit fairly weak compared to well-established disinfection agents), it is often suggested as a natural clean er for the home. And yes, it will do the job as a cleaner as the acid is effective against mould, but so are salt, lemon juice, hydrogen peroxide, tea tree oil and baking soda. Apple cider vinegar because of its low pH, is great against alkaline grime such as hard water and mineral deposits as well as soap scum. But again here, supermarket private label vinegar will do the same job.
And beyond that, there are actually some pretty compelling health reasons NOT to be taking ACV as a daily health tonic. ACV has a pH of around three, so it can dissolve the tooth structure when it comes into contact with the teeth. And if the erosion is severe, this can lead to the need for extensive and expensive dental care. And the risk is not just a theoretical one, because in at least one of the clinical trials with vinegar that I’ve been mentioning it also monitored dental erosion over 8 weeks and it went up 18 percent in those taking vinegar. So, if you still want to take a daily shot of apple cider vinegar or any other type of vinegar, please dilute it first. https://www.liebertpub.com/doi/abs/10.1089/jmf.2020.0108
Summary
Apart from it making a nice salad dressing or even a handy all-purpose domestic cleaning agent, there aren't that many compelling health reasons to be taking apple cider vinegar. But at least some of those claims have some evidence behind them, but perhaps you should ask yourself if any of it is worth it if it means taking vinegar shots.
So that’s it for today’s show. You can find the show notes either in the app you’re listening to this podcast on if it supports it, or else head over to my webpage www.thinkingnutrition.com.au and click on the podcast section to find this episode to read the show notes.
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I’m Tim Crowe and you’ve been listening to Thinking Nutrition.