Lemon water: is it worth the squeeze or just sour hype?

Do you want to lose weight, boost your metabolism, improve your digestion, detox your body, and have glowing skin all while keeping your body nicely alkalised and in balance? You can. All you need do is start each day with a glass of water with the juice of a freshly squeezed lemon in it. I mean water is good for you. And lemons, being a fruit, are good for you. So why not combine the two and get a quantum level of health-boosting synergy? Okay, so now for a dose of reality as I explore the whole lemon water trend and pull apart those amazing health claims to see what is hype and what is reality.

Links referred to in the podcast

Effect of lemon juice on the glycaemic response to bread https://pubmed.ncbi.nlm.nih.gov/35013789
Effect of lemon juice on kidney stone recurrence https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8683665

Episode transcript
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Lemon water is all the rage these days. And a quick search of the Internet finds no shortage of glowing health reports to do with improved digestion, ridding the body of toxins, boosting weight loss, turbo-charging your immune system and balancing the body's pH. And it’s also great for your skin. Sign me up.

So what is lemon water? It’s simply the juice of a lemon added to hot or cold water usually drunk first thing in the morning. Some people may add a few additional ingredients like honey, mint, turmeric or cayenne pepper, but it is the lemon water that is the base drink and what I’ll focus on for this podcast.

See let’s dive straight into all of the nutritional goodness you get in your glass of lemon water. If you used a very generous squeeze of lemon, let’s call it 50 grams of juice, then you’ll be getting about 40 kilojoules or 10 Calories and about 20 milligrams of vitamin C. That amount of vitamin C is a bit under half the recommended daily amount using Australian and New Zealand recommendations and about a third if you use US recommendations.

So a not insignificant amount of vitamin C to be sure. And let’s not forget that over 250 years ago (well before vitamin C was characterised and named as a vitamin), thanks to the work of British physician James Lind, he all but eradicated the terrible disease scurvy which was rampant among British sailors on long sea voyages because of the lack of vitamin C from fresh foods in their diet. And he did this through controlled experiments to finally settle on the juice of lemons or limes as the key food to restore them to health and prevent scurvy from occurring in the first place. Vitamin C is important as among its many roles is being essential for the production of collagen. Collagen is responsible for the elasticity and strength of the skin and why some of the symptoms of scurvy relate to bleeding gums, poor wound healing, and bruising.

So yep, if you’re at risk of scurvy, then lemon water will certainly be of huge benefit. Of course, any citrus fruit will give you loads of vitamin C and eating an orange or kiwi fruit would give you four-times the amount compared to your lemon water. And foods like broccoli, tomatoes, red capsicum and a whole bunch of others are also great sources. So if you’re relying on just lemon water to get your vitamin C for the day for months on end, then you’ve got some serious problems going on with your diet and lifestyle – maybe get that checked out first. But after vitamin C though, it is a fail as far as the nutritional profile goes for lemon water for getting close to any other nutrient needs you may have apart from the biggest one of all: water.

So, let’s look at water. If you’re struggling to get enough water each day, then lemon water will certainly help here and if the citrus tang encourages you to drink more, then that isn’t such a bad thing. Especially if you are replacing soft drinks, sports drinks and even fruit juices with lemon water – that’s a lot less sugar and calories you’ll be having in your diet. So, for the average person that’s a good thing so lemon water here will be better for your health, but so too would….plain water as you’re just replacing more calorie-dense sources of water with one low in calories. You could get the same result by drinking green or black tea by the way.

What about those weight loss claims? Any claims about weight loss to do with lemon water all stem from this: that if you’re drinking lemon water in place of food or other liquids full of calories then that can be enough to kick start weight loss. And research studies have found that when people increase their water consumption, especially before meals, and replace calorie-filled beverages with water, then at least in the short -term, it can result in a small amount of weight loss if the habit is maintained. But adding lemon to the water doesn't make it any better or worse for increasing the rate of weight loss or ‘fat burning’.

So let’s call that two wins for lemon water so far: vitamin C and water. But neither property is owned by lemon water and their effects are well-and-truly overhyped when you consider a person’s whole diet over the course of the day and all the other sources of vitamin C they would have and how much water they would drink in other beverages and contained naturally in food too.

But one bit of intriguing research has profiled the effect of lemon juice on digestion when consumed at the same time as a meal containing starch. Here, it is the effect of all that lemony acidity that reduces the activity of the enzyme alpha-amylase found in saliva in the mouth. Alpha-amylase is involved in the process of starch breakdown which commences in the mouth. All this translates to a lower glycaemic response when lemon juice is drunk with starch-containing food which could have some relevance to people with diabetes. And I’ll link to the research study about this in the show notes. https://pubmed.ncbi.nlm.nih.gov/35013789

But it doesn’t mean you won’t absorb any of the starch if you drink lemon water with a meal, only that it may take a bit longer to absorb. And there is nothing special about lemon juice – similar effects have been seen with vinegar - be it apple cider vinegar or home brand vinegar off the supermarket shelf – it all does the same thing because of its acidity. So there could be some truth to the claims about lemon juice improving digestion, but the disclaimer here is that you have to drink it at the same time you are eating a meal containing starch. Contrast that with the typical claims made about lemon water to do with starting your day with a glass of it to help with digestion – that will have zero effect on your digestion of food as most of the food you eat will be later in the day.

Metabolism-boosting claims

And what about those claims you hear of lemon water ‘boosting your metabolism’? There are many pills, supplements and foods that claim to boost metabolism and burn fat. Most of these claims are unproven. Some substances such as caffeine and chilli do have a small effect on metabolic rate, but the effect is very small.

And there is really no plausible metabolic mechanism for why a glass of diluted lemon juice should do anything to your metabolism short of the tiny amount of energy that your body uses to digest and absorb and move that lemon water along your gut. That is called the thermic effect of food and it is the energy required to digest and assimilate food. It can differ depending on the macronutrient content of the meal with fat having an energy cost of about 5%, carbohydrates about 10% and protein around 25%. Before you get too excited about all of this, you can’t ‘eat yourself thin’. Think of the thermic effect of food as more of an energy tax on food, but most of the energy in the food you will still make use of. So considering the amount of energy in a glass of lemon juice is tiny to start with, at just a few calories, then the thermic effect of food here is so small as to be effectively zero but to be kind, let’s call it 1 Calorie for that glass of lemon juice. Ozempic it is not.

But does lemon juice boost your energy? The answer is ‘probably’ but it would all be from the placebo effect if you were drinking lemon juice because you felt it was good for you and you were all Carpe dieming each morning with your lemon water ritual.

But one area where there could be some health benefits of lemon juice relates to reducing the risk of recurrence of kidney stones. Kidney stones are hard deposits of minerals and acid salts that stick together in concentrated urine. They are quite common, and people who get them often get them repeatedly. The citric acid found in lemons, and of course, all other citrus fruits, may help reduce the risk of kidney stones recurring by binding with urinary calcium and preventing crystal growth by creating a less favourable environment for kidney stone formation.

And there is now clinical trial evidence to support this with a recent randomised-controlled trial published in 2022 that built on previous research finding that in 203 people with recurrent kidney stones who took either 60 mL of fresh lemon juice twice per day or nothing at all, there were lower rates of kidney stone recurrence over 2 years. And I’ll link to this study in the show notes. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8683665

So there could be something to this story of citric acid and kidney stones as there is also some mixed evidence that lemonade could do something similar. But again, it is from the citric acid that is added to these types of drinks, so don’t use it as an excuse to down a litre of Sprite each day for your kidney health.

Alkalising your body

But one claim made about lemon juice needs to be called out for the BS that it is: and that is to do with its ‘alkalising’ effect on your body. Alkaline diets have been promoted for years as a magical cure-all to treat or prevent cancer, heart disease, low energy levels, and a whole host of other illnesses. The premise behind the whole alkaline trend is related to something called the acid ash hypothesis which underlies this diet. It goes like this: when we eat certain foods like meat, poultry, cheese, fish, eggs, and grains, ash is produced in the body. The type of ash is determined by the relative content of acid-forming components in a food such as phosphate and sulphur, and alkali-forming compounds such as calcium, magnesium, and potassium. Most fruits and vegetables (and that includes lemons even though we think of them as an acid food) form alkali compounds in the body.

Where to start….As with any crazy diet, there is always a kernel of truth behind it. And it is true that different types of foods produce different types of metabolic by-products. Alkaline ash is produced by fruits, vegetables, nuts and legumes. Neutral foods are more natural fats. And the ‘evil’ acidic foods are meat, poultry, fish, dairy, eggs, grains, and alcohol.

Back to pH and why this diet is totally cray. pH is, of course, a measure of acidity or alkalinity. The pH scale ranges from 1 to 14 with 1 being strongly acidic, 14 being strongly alkaline, and 7 neutral. Anything below 7 is acidic, and anything above 7 is alkaline (also known as basic). Your stomach acid and also battery acid has a pH of about 1, lemons a pH of 2, grapefruit about 3 and black coffee a 5 or 6. While on the other end, seawater is about pH 8 and liquid drain cleaner has a pH of 14. I guess Draino would count as a health tonic supplement in the alkaline diet world then.

Advocates pushing the alkaline diet claim that since the normal pH of the blood is slightly alkaline at just above 7 at 7.4, then you should eat alkaline foods and shun acidic foods to keep it there. Here’s the thing: if food could really make an impact on blood pH in either an acidic OR alkaline direction, it would be life-threatening. A blood pH below 7.35 is called acidosis and above 7.45 it is alkalosis and both are medical emergencies that can result in death.

The body keeps blood pH in a very tight range thanks to the coordinated actions of the lungs and kidneys. But anyone who has studied physiology would know this sort of basic stuff. Those promoting an alkaline diet are not in that group.

Food though can change the pH of the urine and that's one of the regulatory mechanisms the body uses to buffer against too much acidity or alkalinity, along with respiration. Urine though is contained in the bladder so does not affect the pH of any other part of your body. So, while an alkaline diet may change the pH level in the urine it has not been shown to cause a sustained change in blood pH levels. That’s all because our natural acid-base regulatory mechanisms don’t need a special diet to work so any effect of food on blood pH is minimal and transient.

There is the argument that those pushing alkaline diets sometimes come up with when they actually look at a physiology textbook and acknowledge that acidic foods don't change blood pH, that they instead deflect this to the stress acidic foods place on the body from the need to buffer the pH against the acidity by pulling out alkaline-rich minerals like calcium, phosphorus, and magnesium from the bones, teeth and organs to buffer against the extra acid load. They say this leads to osteoporosis and fatigue, and compromises our immune system, making us vulnerable to viruses and disease. That claim just doesn't hold pH 7 neutral water. Yes, that's a great theory which if you want to apply to 'acidic foods' will apply equally to 'alkaline foods' so an all-alkaline diet would be just as harmful and ‘stressful’ from the need of the body to buffer the pH back into the tight range of 7.35-7.45.

And all this focus on blood pH pushed by alkaline diets ignores the one simple observation: pH differs all throughout different body compartments. You want a very acidic stomach to help with good digestion. While your mouth salvia is slightly acidic at about pH 6 which is optimal for salivary amylase that helps with starch breakdown. While a lower pH in the colon from bacterial fermentation is linked to favourable changes in disease risk profile. Then there is your skin which has a pH of about 5. Just what on earth is an alkaline diet trying to achieve by just targeting the blood?!

An alkaline diet 'works' because it gives a person a selective list of foods to eat and avoid which means lots of fruits and vegetables (and lemon water too obviously) and less highly processed food, foods high in sugar and alcohol. That's it. You don’t have to believe in the crazy that is the alkaline diet, spend money on alkalinised water, or squeeze a lemon into your water while needlessly cutting out otherwise healthy foods like grains from your diet to make a positive change to your diet and life.

The downsides

So, what of the downsides to lemon water? The only ones of note are an effect on your tooth enamel if you’re making this a regular habit and more stomach acid production. So consider using a straw and rinsing your mouth with plain water afterwards if this could be a concern for you and your teeth. Some people with a history of heartburn can find symptoms are aggravated by drinking lemon water, but this can be variable.

Summary

So, let’s wrap all this up. Lemon water can be an enjoyable and refreshing drink and an easy way to add a bit of extra vitamin C into your diet. And if you’re drinking lemon water in place of sugary drinks that could be a plus for your body weight and health. But most of the benefits attributed to lemon water have been blown out of proportion.

If you enjoy drinking lemon water, then drink it. Just don't expect any magical changes in your body weight, skin or body chemistry. At least nothing that can’t be gained from drinking plenty of water throughout the day and eating an orange or two. But if you don’t like drinking it, then you’re not missing out on much at all.

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, 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.

If you find this podcast of value, then please consider sharing it with your friends and colleagues. Or maybe even leave a review. This all helps to increase the ranking and reach of the podcast, which means a big win for credible evidence-based nutrition messages and making the world a slightly less confusing place.

I’m Tim Crowe and you’ve been listening to Thinking Nutrition.

Thinking Nutrition

Lemon water: is it worth the squeeze or just sour hype?

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