In my misspent youth, I foolishly attended a number of super boring networking events. I have clear memories of nibbling celery stalks (or "crudites" as we like to say in Europe) while desperately pretending to feign indifference to other high calorie, delicious, pastry covered food choices.
I really dislike the smell and taste of celery (it reminds me of Irish stew from my childhood) and I usually try to mask the taste and smell of celery by smothering the little green stalk in blue cheese.
As the holiday party season is around the corner, I have to ask if there is any benefit to nibbling celery?
Does the blue cheese dip offset any potential health benefits of the celery?
Time for a celery unboxing.
What Is Celery?
Celery (Apium graveolens L.) is a seed spice which belongs to the Umbelliferrae family. As mentioned above, it has a very distinctive flavor and aroma. About 2% of celery is made up of volatile oils including limonene, selinene and 3-n-butul-4-5-fatty oil.
Anatomically speaking, celery has a stalk, seeds, and leaves.
Practically speaking, celery has oil, seeds, stalk, and leaves which are used for a wide variety of culinary and medicinal purposes.
The average nutritional content of 100 gm of celery is:
- Water 95 gm
- Energy 18 kcal
- Protein 1.18 gm
- Fat 0
- Carbohydrate 3.53 gm
- Fiber 1.2 gm
- Sugar 1.8 gm
- Calcium 40 mg
- Iron 0
- Potassium 260 mg
- Sodium 82 mg
- Vitamin D 0 mg (1).
There are over 2000 celery products for sale on Amazon including celery salt, oil, flakes, seeds, stalks, juices, and capsules. A 500mg celery capsule costs about $0.10.
Is There any Research?
There are 1,109 articles related to celery in the scientific literature which includes just 14 clinical trials. To put this into context, there are over 3,000 publications related to carrots which include over 90 clinical trials. Go carrots.
Does Celery Fight Infections?
There are no clinical trials looking at celery as an anti-infective agent.
There are a handful of papers related to infections but the majority of these have to do with plant infestations and not the anti-infective properties of celery per se.
I have been working as an infectious diseases physician for years and have never come across celery as a folk cure in clinical practice, however, according to the literature, it is a popular folk cure for infections.
There is a 2009 paper from China which studied the effects of celery against laboratory strains of Helicobacter pylori (cause of peptic ulcer disease), Campylobacter jejuni (cause of food poisoning) and Escherichia coli (cause of kidney infections) (2). The study showed that celery inhibited the growth of Helicobacter but not the Campylobacter or the Escherichia coli.
A 2013 study looked at the "antiulcerogenic and antibacterial" activities of celery (an odd combination in one study) (3). This study again looked at laboratory strains of bacteria and found that celery inhibited the growth of Escherichia coli, Pseudomonas and Staphylococcus aureus.
This is not consistent with the results of the 2009 study which makes it difficult to draw any meaningful conclusions. Plus the proclivities of laboratory strains of bacteria tell us little about their activity in humans.
There are some interesting papers that I came across linking celery and infection (not anti-infection though).
In February 2010, the Texas Department of State Health Services identified an outbreak of listeriosis which appeared to be related to visits or in-patient stays in hospitals (4). A major investigation was carried out by local health care officials and the Center for Disease Control.
They discovered that the same distributor supplied food items such as meat, poultry, prepared, and frozen foods to the hospitals. They subsequently identified that diced celery in a chicken salad was the culprit. Oops.
There is no clinical research to support celery as an anti-infective agent.
Does Celery Help Prevent Urinary Tract Infections?
A 2018 paper shows that celery helps prevent Escherichia coli from sticking to bladder cells in mice who were deliberately infected with the bacteria by injection it into their urethras (Ouch) (5). On the plus side, this is consistent with the 2013 paper from China mentioned above (2).
On the negative side, this is inconsistent with the 2009 study results (3) and anyway, this is an extremely artificial system which is totally divorced from the clinical reality of patients with kidney or bladder infections.
There is no clinical data to support the use of celery in the prevention of urinary tract infections.
Does Celery Lower High Cholesterol?
A comprehensive review of natural products with lipid-lowering effects was carried out by Iranian researchers and formed part of a PhD thesis for a local academic (6). Kudos to the PhD candidate for publishing the results of his/her PhD in a scientific journal as far too many PhDs sit gathering dust in libraries.
The PhD candidate cast a wide net and looked at products such as ginger, dandelion, ginseng, blueberries and primrose oil. The review looked at 2,183 papers and extracted 92 relevant publications and found that celery can reduce lipid, cholesterol and triglyceride production.
There is evidence that celery can reduce levels of total lipids, cholesterol and triglycerides.
Does Celery Help in Weight Loss?
There are no studies showing that celery helps with weight loss. I see that other blogs extrapolate that celery can help people lose weight as it is relatively nutrient-dense, water-rich and low in calories. So yes, I can see that choosing celery over a carbohydrate-rich pastry at a soiree could help from weight gain.
There is one big problem with this theory. It assumes that people choose celery over a high carb food alternative and (unlike me) don't smother the celery in blue cheese.
Celery is nutrient-dense and low calorie but has not been shown to result in weight loss.
Does Celery Lowers Inflammation?
It is commonly said that celery is as potent an anti-inflammatory as aspirin or non-steroidal anti-inflammatories without the gastric side effects. The studies that underpin this are as follows.
Australian investigators looked at the effects of a range of over the counter pain killers versus celery in rats who were artificially induced to have fevers and arthritis (7). Celery seed extract was as effective as the non-steroidal anti-inflammatory, ibuprofen, without the associated gastric irritation. That sounds good.
However, the small print in the study also says that not all brands of celery seed extract are created equally. Some extracts had no efficacy at all, while others were highly effective. The authors concluded the paper by calling for quality control systems for herbal over the counter products and not that celery is a great pain killer/anti-inflammatory.
A follow-up paper from the same research group states that celery seed extract can '(i) amplify the potency of salicylates and prednisone for treating pre-established chronic inflammation (arthritis, fibrosis) and (ii) reduce the steroid's gastrotoxic and lymphopenic side effects' in rats. The full details of the studies that led to these claims were not available for analysis (8).
A 2017 study from China showed that glycosides from celery reduced inflammation (nitric oxide production from macrophages) in a laboratory model (9).
There are no human clinical trial data to show that celery is an effective anti-inflammatory agent.
Does Celery Prevent or Treat High Blood Pressure?
A 2014 cross-sectional study looked at the association between vegetable intake and blood pressure for 2195 Americans ages 40-59 in the International Study of Macro/Micronutrients and Blood Pressure (INTERMAP) (10). This is an observational study. The study team used 24-hour dietary recalls and eight blood pressure measurements per patient.
Dietary recalls can be flawed and there is always the chance that patients may tell you what they think you want to hear. As an example, I may have told you in the past that I ate celery in the past 24 hours and conveniently left out the blue cheese bit.
Cooked (but not raw) celery was associated with significantly lower blood pressure. I am not sure why there was a difference between raw and cooked celery - if anything, we might have expected that raw celery would have been better. Just goes to show that guessing has no place in science.
A study from Iran looked at the effects of celery on blood pressure in two groups of rats: rats with normal blood pressure and rats with high blood pressure (11). This study showed that celery had no effect on blood pressure in rats with baseline normal blood pressure.
Celery reduced blood pressure and increased heart rate in rats with high blood pressure. Again this is confusing. Decreasing blood pressure would be considered to be a good thing in the presence of hypertension. However, increasing heart rate might not be considered to be very heart-friendly. N-butylphthalide was identified in the study as the active anti-hypertensive agent.
Celery does seem to lower blood pressure (especially in people with hypertension) but in view of the fact that it may also raise the heart rate, I could not recommend this as an intervention until we have a better understanding of the mechanism of action and clinical effect of celery in humans.
Does Celery Help Prevent Ulcers, Boost Digestion or Reduce Bloating?
As mentioned above, celery can inhibit the growth of Helicobacter which is a causative agent in peptic ulcer disease (2). However, this data was not taken from a human clinical trial.
A 2010 study in rats deliberately induced peptic ulceration in rats using non-steroidal anti-inflammatories (indomethacin), cold temperatures and high concentrations of alcohol (12).
Pre-treatment of these rats with celery extract at doses of 250 and 500 mg/kg showed significant protection of the stomach mucosa and a reduction in the secretion of gastric acid. Moreover, the celery was well tolerated and had a wide margin of safety.
Finally, a study from Iran looked at 150 patients with functional dyspepsia which refers to feeling full, abdominal pain, bloating and vomiting (13). The patients were randomized to either placebo, omperprazole or a combination of celery plus Trachyspermum copticom (another member of the Umbelliferrae family which is used in Iranian traditional medicine).
The study took place over a period of 8 weeks. The researchers found that the combination of celery plus Trachyspermum copticom significantly reduced symptoms of burning, fullness, bloating and fullness as compared to the placebo or omeprazole arms of the study.
The combination of celery plus Trachyspermum copticom was as effective as omeprazole for pain. As with any study looking at combination interventions, it is hard to isolate out the relative contributions of celery versus the Trachyspermum copticom.
Available data suggest that celery may help with a range of gastrointestinal symptoms but it has to be said that there is a paucity of human clinical data.
Does Celery Help Protect Against Cancer?
There are no randomized human clinical trials to help us answer this important question.
A 2013 study from China looked at 132837 men and women and evaluated the effect of diet on liver cancer risk (14). This was another 'eat and tell' study design. The study took place over 11 years for women and over 6 years for men.
A vegetable based diet was protective against liver cancer and especially in people with chronic liver disease. On deeper analysis, intake of certain vegetables, including celery, was associated with a lower liver cancer risk.
A laboratory based study showed that celery extract was shown to prevent cell growth and promote cell death in a laboratory model of stomach cancer cells (15).
There is growing interest in the possible role of the flavonoid, apigenin, in the prevention and treatment of cancer. Apigenin is found in celery. A study from the Brigham Women's Hospital, Boston looked at the dietary intake of 3234 women with cancer (16). The women were all aged 45 years or older.
Intake of apigenin was assessed using a questionnaire. Using complex statistical analysis, the investigators drew a blank and found no significant relationship between intake of foods such as celery and the risk of breast, colorectal, endometrial or ovarian cancer.
Finally, Serbian investigators showed that celery reduced the toxicity of a commonly used chemotherapy drug called doxorubicin (17).
The data on a possible role for celery in cancer is inconclusive at this time. More detailed studies looking at the impact of celery on the prevention and treatment of different types of cancer are needed.
Does Celery Protect Liver Health?
Thai investigators showed that celery extract protected against the development of free radicals and increased liver antioxidant enzyme activity in an experimental rat model of liver toxicity (18).
Serbian investigators carried out a suite of laboratory studies looking at carbon tetrachloride induced liver damage (19). The results of the in vitro studies showed that celery root and leaf extract protected the liver against carbon tetrachloride damage.
The results of the in vivo studies showed mixed results. Sometimes the celery extract helped. Other times it made the liver damage worse. The authors concluded that the mixed effects were probably due to different flavonoid components in different celery extracts.
Indian investigators designed a study to see of celery could protect against liver damage caused by paracetamol or acetaminophen (20). They used a freshwater fish, Pangasius sutchi experimental model. In this study, 24 fish were divided into 4 groups:
- a control arm
- an acetaminophen arm
- a celery arm and
- an acetaminophen and celery arm.
The fish exposed to acetaminophen developed an acute liver injury. These acute liver changes reversed in the cetaminophen plus celery arm of the study.
Speaking of the liver and celery, an extraordinary case report came from a group of doctors in China in 2013 (21). They were looking after a 51-year-old lady who presented with abdominal distension.
The cause of her symptoms was identified as an intact celery stalk blocking her biliary tree (a network of tubes that lead from the liver to the gallbladder). The doctors think that the celery stalk somehow migrated from the duodenum into the biliary tree. Curiouser and curiouser.
There is insufficient human clinical data to make a call on the effect of celery on liver status.
Is Celery Safe?
Many restaurants have a disclaimer on their menus which says that their food has been prepared in an area that may contain celery and that people with food allergies should consult with the waiter. Reason being that celery root is a known cause of food allergy.
Sometimes, patients report that they are "allergic" to various things but the diagnosis may/not always be correct. Allergies can be fatal which means it could be dangerous to de-label people as "non-allergic" unless this is definitively proven to be the case.
Swiss investigators carried out skin prick tests with celery extracts, crude celery, and different pollen extracts in 32 patients with a history of an allergic reaction to celery (22). Skin testing in a safe, controlled environment confirmed that 22 of the 32 patients were truly allergic to celery.
A further 4 patients were confirmed to be allergic to celery using other testing modalities. The authors concluded that celery is an important food allergen.
The same Swiss research group set about understanding whether or not cooking celery made any difference to people with known celery allergy (23). Again they used an extremely controlled environment in order to ensure the safety of their patients and showed that celery can cause allergy when cooked or when used as a spice.
This means that the allergenic part of the celery is not killed off during the cooking process.
From a clinical perspective, people who are allergic to celery can be cross-allergic to other agents such as carrot, zucchini, mugwort, ragweed, and birch pollen. French investigators report two cases of anaphylaxis to celery in patients who were allergic to ragweed and mugwort (24).
This has been called the "celery-carrot-mugwort-spice syndrome," or the "celery-mugwort-birch-spice" syndrome.
Celery allergy can be severe and life-threatening. Polish investigators report a case of a 28-year-old lady with seasonal allergies who developed anaphylactic shock after eating fresh celery (25).
Raw celery can contain compounds called psoralens. These are chemicals that can make the skin really sensitive to sunlight and UV light. The celery does not actually contain the psoralens itself. The psoralens are made by a pink rot fungus that shows up as brown spots on the celery. Choosing celery without brown spots is a workaround to avoid this problem.
Finally, a study from China showed that pesticide residue was found in 58% of 300 samples of celery tested. Any health benefits of celery could be offset by eating a pesticide contaminated brand (26).
Celery can interact with thyroid replacement therapy and care needs to be taken in patients taking thyroid supplements.
Celery also can cause uterine contractions and so is best avoided during pregnancy.
Alright, I confess that I am no great fan of celery. It has to be said that I did disclose my bias in just the same way that doctors are expected to disclose any financial conflicts of interest. Even if I am biased, I am also a self-confessed research nerd and always bow to research. That being said, I only like high quality, well-designed studies in real live humans. Problem. Celery does not score well for high quality, well-designed clinical trials.
The best data on celery relates to lipid-lowering properties and possible relief of gastrointestinal symptoms.
Nothing that I read has convinced me that celery has the type of unequivocal health benefits that make it worth eating and especially for people who do not care for it.