Is Apple Cider Vinegar a Miracle Food?

ACVfood

Is Apple Cider Vinegar a Miracle Food  – What is the Evidence?

By: Peter Fitschen, PhD

Read Time: 6.7 oz of coffee

Vinegar can be made from nearly any fermentable carbohydrate source, including apples.  To make vinegar, yeast ferment sugars into alcohol which is then converted into acetic acid by bacteria.  The final acetic acid concentration of commercially available vinegar is 4-7 percent [1].

Recently, mainstream media has marketed apple cider vinegar as a cure for literally everything.  From weight loss to cancer to detoxification and many other claimed uses, it can seem like all you need to do is take some apple cider vinegar and all of your problems will be solved.

Coming from a science background, any time I hear these types of claims I ask, “What is the evidence?” 

To answer this question, I dug into the scientific literature on apple cider vinegar (and vinegar in general) to determine which of these claims have sound scientific backing and which do not.  Below is a summary of the current peer-reviewed scientific evidence for a number of claims made about apple cider vinegar.

Blood Sugar

This is a claim that has been investigated.  Studies in rodents have found that both vinegar [2] and apple cider vinegar [3] have positive effects on blood glucose control.

In humans, consumption of vinegar prior to a carbohydrate containing meal has been shown to reduce blood glucose response by approximately 20-30 percent [4, 5].  However, it should be noted that total area under the curve for blood glucose 2hrs after a meal was not different between a group that consumed vinegar and one that did not [6].  What this means is that while vinegar consumption reduces the initial increase in blood glucose, it does not prevent glucose absorption and instead delays it. 

Indeed, vinegar consumption has not been shown to interfere with carbohydrate absorption [7].  Instead, consumption of apple cider vinegar [8] or regular vinegar (most often made from rice) [9] has been shown to reduce gastric emptying rate. 

Although vinegar has been shown to reduce the initial glycemic response to a meal, it should be noted that the significance of the glycemic index and glycemic response of a meal to overall health in non-diabetic individuals has been debated [10].

In insulin resistant individuals, increases in insulin sensitivity have also been observed following consumption of vinegar with a high carbohydrate meal [11].  In addition, a small, short-term intervention in type 2 diabetics observed a small reduction in fasting blood glucose when apple cider vinegar was consumed prior to bed [12].  Similarly, a small study in diabetics observed a slight decrease in hemoglobin A1C levels after consumption of 2 tablespoons vinegar twice daily for 12 weeks [13].  However, it should be noted that this effect was not observed in a larger controlled trial in non-diabetics [14].

Although more research is needed on this topic, it does appear that consumption of vinegar with high carbohydrate meals may help to blunt the glycemic response and also may help blood glucose control diabetics.

Weight Loss

Many in the health and fitness community promote apple cider vinegar for weight loss.  Fortunately, some scientific investigation has been made into this claim. 

Rodent studies have found that acetic acid administration increases fatty acid oxidation and prevents fat accumulation [15, 16].

In humans, consumption of a vinegar with a high glycemic meal had a non-significant trend to reduce caloric intake throughout the rest of the day by 200 calories [17].  This was thought to be due to a decrease in gastric emptying rate resulting in increased satiety.  However, there is some evidence that the appetite suppressing effect may actually be due to nausea caused by vinegar consumption [18].

To date, only one study has investigated the effects of a vinegar intervention on weight loss in humans.  Kondo et al. [19] recruited 155 obese Japanese individuals and assigned them to either 15ml vinegar, 30ml vinegar or placebo daily for 12 weeks.  Weight loss was observed in a dose-dependent manner.  The 15ml group lost 1.2kg, 30ml group lost 1.9kg and placebo group body weight remained unchanged following the intervention despite no differences reported in caloric intake. 

However, it should be noted that participants self-reported nutrition intake which has been shown to be highly inaccurate in obese individuals [20].  Moreover, it should be noted that since this study was published in 2009, the results have not been replicated.

Therefore, although vinegar consumption may increase satiety to some extent (as a result of either delayed gastric emptying and/or nausea); far more research needs to be done before claims of accelerated weight loss can be made.

Cardiovascular Disease

A number of claims related to cardiovascular disease risk factors and mortality have been made about apple cider vinegar.  However, much of the existing data to support these claims are from rodent studies and very little research has been done in humans.

In rodents, apple cider vinegar consumption improved blood lipids [3, 21] and reduced oxidative stress [22].  Black vinegar has also been shown to reduce oxidative stress in rodents [23].  In addition, high doses of vinegar have been shown to reduce blood pressure in an animal model of hypertension [24].

In humans, an observational study observed a correlation between consumption of oil and vinegar salad dressings and reduction in cardiovascular disease mortality in women [25].  However, it should be noted that these individuals also consumed a greater amount of polyunsaturated fatty acids; therefore, it is not clear if the reduction in cardiovascular disease mortality observed was due to vinegar, polyunsaturated fatty acids or some other factor.

To date, few trials looking at vinegar consumption and cardiovascular risk factors has been conducted.  In addition to weight loss, Kondo et al. [19] observed a reduction in triglycerides; however, as previously discussed after publication of this data in 2009, the findings have not been replicated.  Panetta et al. [14] observed no significant change in blood lipid after 8 weeks of daily apple cider vinegar consumption in a randomized controlled trial of 97 non-diabetics.

Moreover, no studies to date have been performed examining the effects of regular vinegar consumption on outcomes such as cardiovascular events or mortality.  Therefore, much more research is needed before any claims can be made about vinegar and reduction of cardiovascular disease risk.

Cancer

Recently, there have been an increased number of claims regarding apple cider vinegar consumption and cancer; however, as a whole there is not a lot of evidence to support this claim.  Studies from cell culture [26] and animals [27, 28] have shown anti-cancer effects of vinegar.  However, observational studies in humans have been mixed showing both an increase [29] and decrease [30] in cancer with increased vinegar consumption.  Thus, this claim is not supported at this time.

Skin

Numerous skin-related claims have been made about apple cider vinegar including: acne treatment, improvement of wrinkles, wound healing, mole removal, reduction in bruise discoloration and others.  However, to date there is no evidence to support these claims.  Vinegar has not been shown to be effective for wound care [31] or lice treatment [32].  Moreover, chemical burns have been reported from attempted mole removal [33] and prolonged skin exposure [34] with vinegar.  Based upon these findings you would be better served staying away from vinegar for skin treatment.

Oral Health

Apple cider vinegar has been claimed to whiten teeth and improve bad breath.  However, there is not evidence to support these claims.  Vinegar is acidic; therefore, prolonged exposure can erode tooth enamel like any other highly acidic food [35].  With that being said, there is some evidence that vinegar may be an effective denture cleaner [36].

Antibacterial

There have been a number of claims made about the ability of apple cider vinegar to cure illness such as the common cold or reduce the duration of a sore throat.  However, the evidence to support these claims is poor.

Much of the research on the antibacterial effects of vinegar has been focused on its ability to kill pathogenic bacteria in food [37].  It has also been investigated as a cleaner, but has been shown to not be as effective as commercially available cleaners [38].

In shrimp, high dosages of apple cider vinegar (1-4% of the diet) enhanced expression of immune related genes [39].  However, the relationship between vinegar and immunity, illness or throat soreness has not been studied in humans.  In fact, esophageal injury has been reported from consumption of apple cider vinegar supplements.  This lead to a follow up study which found wide variability in the composition of apple cider vinegar supplements [40].

Allergies

Apple cider vinegar has been claimed to reduce a wide array of allergies.  However, the supporting data for this claim is lacking.  To date, only one study on vinegar and allergies has been performed in humans.  In this study 7 subjects with food allergies to egg, chicken and lentils were subjected to skin prick tests in which foods were prepared with or without white wine vinegar.  The foods prepared with vinegar resulted in a reduction in reaction during the skin prick tests [41].  However, it should be noted that vinegar is acidic and likely denatured proteins similar to the denaturation of proteins that occur in the stomach as part of dietary protein digestion.  Therefore, it is unclear if denaturation of proteins by vinegar prior to oral intake would have a different outcome than protein denaturation that occurs in the stomach.  It should also be noted that this is only one study in 7 individuals and far more research is necessary before vinegar can be claimed as effective against allergies.

Inflammation

Many individuals claim apple cider vinegar will reduce inflammation from arthritis or other inflammatory conditions.  However, evidence to support this claim is scarce.  In an animal model of colitis, large doses of vinegar reduced inflammation, improved gut bacterial populations and attenuated body weight loss [42].  To date, this data has not been replicated in humans and there is no human data supporting these claims.

Fertility

There have been some claims that apple cider vinegar improves fertility.  The only human study along these lines to date was a small study of 7 Japanese women with polycystic ovary syndrome (PCOS) that did not have a normal menstrual cycle.  After consumption of 15g vinegar daily for 90-110 days, 4 of the 7 women re-gained their menstrual cycle and this was thought to be due to vinegar’s effect on normalizing insulin resistance commonly associated with PCOS [43].  However, far more research is necessary before any claims about apple cider vinegar and fertility can be made.

Detoxification

Detox diets are increasingly popular fad diets based around the premise that “toxins” have accumulated in the body and to remove them a dietary intervention is required.  These diets often contain apple cider vinegar due to the claim that it can help detoxify the body.  However, an individual with a healthy liver and kidneys is continuously removing chemicals from the body to prevent them from building up to toxic levels.  Moreover, a recent literature review concluded that there was no evidence that detox diets removed toxins form the body [44].  Therefore, there is no evidence that apple cider vinegar or any other food removes toxins from the body.

pH Balance

Claims have been made that apple cider vinegar can help to make the body’s pH more alkaline.  However, the pH of blood is tightly controlled at 7.35 – 7.45 by the kidneys.  Even slight variations from this range can result in severe illness, hospitalization and death.  Fortunately, there is no evidence that human diets have a significant effect on blood pH in individuals with normal kidney function [45] and there is no evidence to support this claim.

Other Claims

Many other claims about apple cider vinegar and health have been made.  These include reduced acid reflux, osteoporosis prevention, dandruff treatment, energy booster, a reduction in cramps, hiccups and many other claims.  To date, there is no evidence to support these claims.

What’s the verdict?

A majority of claims made about apple cider vinegar and health are not supported by the current body of scientific literature.  There is some evidence that vinegar consumption can reduce the glycemic response to a meal and potentially increase satiety.  Therefore, individuals who are diabetic or who may be trying to lose weight may notice some benefit to consumption.  At 3 calories per tablespoon it won’t eat up all of your daily caloric allotment if you are in one of those situations and want to give it a try [46].  It also likely isn’t going to be detrimental to health or weight loss progress in any way.  However, if you think apple cider vinegar alone will be the solution to your weight loss, you will be greatly disappointed because there is no magic pill.  Ultimately, for weight management and overall health your best bet is to consume an adequate calorie intake for your goals from a nutrient-dense diet, stay active and maintain a healthy body weight. 

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