If you have kidney disease and are working hard to preserve your kidney function then understanding your serum bicarbonate level and metabolic acidosis can be helpful to you.

Disclosure: This post is sponsored by Nephcentric, LLC, the makers of Bicarbi, a bicarbonate supplement. As always, all opinions are my own and current as of day of post. Opinions may change as new research, evidence, or products are released.

I bet you’ve heard about baking soda…

One of the biggest myths floating around the internet is that drinking baking soda mixed in water will cure your kidney disease. This is not true. There is nothing magical or healing about baking soda water and kidney health. So where did this come from?

The reason that baking soda shows up in the research and online as a strategy for preserving kidney function all comes down to metabolic acidosis. Sounds like a confusing medical term, right? Doesn’t have to be and definitely something you should understand if you’re working toward your best kidney health.

What is metabolic acidosis?

“Metabolic acidosis” is a big term. Metabolic acidosis is when there is a buildup of acid in the body fluids. It can happen if you:

1. Don’t get rid of enough acid
2. Make too much acid
3. Can’t balance the acid (1).

Balancing the acid and alkaline environment in the body is an incredible opportunity for preserving kidney function. Understanding when you might be getting close to metabolic acidosis and knowing what to do, may help you preserve your kidney function.

Understanding metabolic acidosis

Metabolic acidosis is an imbalance in the blood. So to understand metabolic acidosis, let’s think about the teeter-totter at the park. When I go to the park with my kids, my 6 year old and 3 year old run to the teeter totter. It’s no surprise that my 6 year old sadly stays stuck to the ground while the 3 year old gleefully perches way up high. Until of course the 6-year old jumps off to run to the slide and the 3-year old hits bottom hard. Ouch! Similar circumstances in the body, only there is harm with imbalance not just when it hits rock bottom.

Like a teeter totter, our body functions best with balance. In the case of kidney health, what we are looking at is an acid-base balance. For example, blood stays within a pH of 7.35-7.45, but usually closest to 7.40.

If our blood chemistry starts getting too acidic or too basic (we can also say alkaline) the teeter totter starts to tip. This imbalance can create compounding problems such as further decline in kidney function. Correcting the imbalance, on the other hand, may be influential in delaying progression of kidney disease (1).

How does the body balance the acid/alkaline environment?

Kidneys are a KEY organ in managing the pH in our blood. I’m not going to dig into all the science here because it is complicated and involves anion gaps and a load of chemistry. What you need to understand more or less is that as kidney function declines the ability of the kidney to get rid of acid and/or balance acid is severely hampered. 

This means you need to know what you can do to support the acid/base balance in your body if your kidney function is decreased. And, yes, diet or supplements are a factor.

First, though, let’s talk about your labs.

How do you know if you have metabolic acidosis?

Metabolic acidosis in CKD is measurable. On your blood work there is a level called the serum bicarbonate or CO2 level. The”normal range” defined on your lab results probably will say 20-30. For sure, if youre serum CO2 is below 20 then you are dealing with metabolic acidosis. But even if the lab doesn’t show up as out of range, you should be watching it closely. 

Why? The therapeutic goal for CO2, per the current research may very well be higher than 20. This means that even if your serum CO2 level looks “normal” it may not be optimal to preserve kidney function.

What CO2 level should I aim for to optimize my kidney health?

Let’s look at a couple studies that were showing impact with keeping serum bicarbonate about 22.

1. In a 2009 study led by Dr. Shah at the Montefiore Medical Center,  they looked at how metabolic acidosis played into renal damage. They had over 5000 patients participants (that’s a lot for a study) over a 3-4 year period. While not a perfect study, they found that when CO2 levels dropped below 22meq/L there was an associated 2 fold increase in dropping GFR. (2)
2. A more recent 2014 study by Dr Raphael and colleagues, looked at over 3000 patients and the connection of metabolic acidosis and kidney decline. Again, they found an associated 2 fold increased in GFR decreasing if CO2 levels were <22. (3)

So what should you do? Definitely be above 22. Some studies suggest aiming more for the 23-27 range. There appears to be some increased risk of calcification or death when the levels start getting above 28 (4). Most importantly ALWAYS watch trends.

Watch your lab trends

I cannot emphasize knowing and watching trends enough. Watching trends will be extremely powerful in knowing when you need to intervene proactively. Have you always been running a serum bicarbonate level of 25, but recently its went to 24 and then your most recent labs 23?

Doesn’t seem like a big drop at – 2 points, right? Your doctor won’t even blink an eye at a level of 24 or 23 because its normal. If you know your trends though, seeing the trend down can help you know that you need to take action to keep it stable or move the dial up a bit.

Talk with your doctor about what therapeutic level he or she is aiming for to make sure that you both have the same goals and expectations. 

What should you do if your CO2 levels start falling?

If you see your CO2 levels falling or if they are already below 20 then it is time to take action!

You can either:

1. Increase your fruit and vegetable intake significantly (if you have a potassium restriction, focus on low potassium fruits and veggies)
2. Talk with your doctor about adding sodium bicarbonate to your regimen

Or you can do both.

Interestingly enough, often the research that studies metabolic acidosis with sodium bicarbonate tablets will have three groups of participants: sodium bicarbonate tablet group, a control group (no intervention), and high fruit and vegetable group.

The outcomes of groups with a high fruit and vegetable intake versus those on a bicarbonate tablet are often very similar. Both the “fruit/vegetable group” and the “bicarb group” always have better outcomes than those in the control group who do nothing.

If you’re still working on dietary changes and are not confident about adding in enough produce then start with sodium bicarbonate tablets. If you’re working on some serious dietary interventions and have increased your fruit and vegetable intake significantly then watch your trends and see where it goes. If it doesn’t help, sodium bicarb might be a valuable addition to your supplement regimen.

Increasing fruit and vegetable intake to lower CO2 levels:

As a dietitian, I love the power of our food to help solve major health issues. The science here is absolutely fascinating too. Here’s what we see in the research on fruit and vegetable intake and CO2 levels.

Dr Goraya and colleagues have done multiple studies on fruit and vegetable intake and reduction of metabolic acidosis. A recent 2019 study by Dr. Goraya and colleagues looked at 108 patients over 5 years. Fruit and vegetable intake helped improve metabolic acidosis and preserve eGFR similar to sodium bicarbonate tablets. This recent though small study, is consistent with their other small research studies preceding it. (6)

Multiple other studies have shown a powerful impact of a diet in fruits and vegetables with an alkaline diet. Getting to an alkaline diet for an effective renal nutrition plan is a topic for another day (7). 

The important part to understand is that more fruits and vegetables usually help decrease help increase serum bicarbonate levels. And give you more vitamins and minerals. And fiber. And protect against heart disease, cancer, and a numerous host of other ailments. Fruits and vegetables are unquestionably powerful in helping people with kidney disease preserve kidney function.

How many fruits and vegetables should I eat to raise my serum CO2 levels?

Most studies base their intake on about 8.5-9.6 servings of fruits and vegetables per day (8). Sound hard? Here’s where you would fit all those fruits and vegetables in. Note this is not a dietary plan. It is an example of how fruits and vegetables could be distributed throughout the day to consume 8-9 servings:

• Breakfast: 1 cup of berries (1 servings)
• Snack: 12 baby carrots (1 servings)
• Lunch: Salad with 2 cups of vegetables/lettuce (2 servings), piece of fruit (1 serving)
• Snack: 1/2 c applesauce (1 serving)
• Dinner:1 cup cooked broccoli (2 servings), 1/2 c zucchini ( 1 serving)

That’s 9 servings. Again, you’d eat other things along with the above fruits and vegetables. For example you might put your berries on cereal or dip your carrots in hummus.  The point is just that it is a completely reasonable goal to get 9 servings in a day fairly easily and many people do.

If you feel like it might be difficult to get enough fruits and vegetables in your diet then working with an expert renal dietitian or taking a sodium bicarbonate tablet, prescribed by your doctor, can also be a strategy to address low serum bicarbonate levels.

What about sodium bicarbonate tablets?

Sodium bicarbonate is a common supplement used to help treat low serum CO2 levels. It usually comes in a tablet form that is taken 1-2 times per day.

In the research it shows up very comparable to a high fruit and vegetable intake. We recommend a food first approach but also realize that there are many situations where having a bicarbonate tablet could be very helpful.

Why do I need a tablet? Why not just use baking soda?

Remember I mentioned that one of the great dietary myths of kidney disease is that taking baking soda will cure your kidneys? Why is that? Where did that myth come from?

First, baking soda is sodium bicarbonate. Yep. Same thing. BUT, the amount of sodium in a common baking soda “dose” versus a bicarbonate tablet is drastically different. 

• 1 tsp baking soda = 1361 mg of sodium (59meq)
• 1 650mg tablet sodium bicarbonate =  178 mg of sodium

Big difference right? 1361 mg of sodium is almost half of the recommended amount of salt in the diet for most people with kidney disease, so you can see how it would be prudent to stick with a much lower sodium tablet. (9,10).

You may still be worried that the additional sodium will raise your blood pressure. Interestingly enough in the studies that have looked at sodium bicarbonate and blood pressure, they didn’t see that it raised blood pressure the same way as salt (sodium chloride) does. 

Do sodium bicarbonate tablets have side effects?

The most common complaint with sodium bicarbonate tablets is bloating or burping. Makes sense though. If you add a base substance straight into an acididic stomach, then yes, you probably will burp. If you have low stomach acid or are on a PPI – both common for an elderly population, then baking soda will further lower the stomach acid which means you may not digest your food well – hence the bloating.

Enteric-coated tablets and GI side-effects

A great solution for avoiding GI side effects but still get the benefits of a sodium bicarbonate tablet is to use a coated sodium bicarbonate tablet. Bicarbi is one such tablet. Because Bicarbi is coated it doesn’t taste salty, nor does it cause the same bloating or GI discomfort as commonly prescribed sodium bicarbonate.

In a 2020 study by Dr Hilton and colleagues, they tested uncoated sodium bicarbonate and regular bicarbonate tablets. This was a small study of 11 athletes and they used pretty high doses relative to what would be taken for someone with CKD. However, between the two groups, the GI side-effects were much lower in the group taking the enteric-coated supplements similar to Bicarbi. (14)

What questions should you ask your doctor about sodium bicarbonate?

Before taking any supplement you should talk with your doctor. Sodium bicarbonate tablets are meant to help with metabolic acidosis. If your serum CO2 levels look great, there is no additional benefit to having sodium bicarbonate.

If your CO2 levels are trending down then you’ll need to talk with your doctor about how much sodium bicarbonate to take. If you need a higher dose, one of the great things about Bicarbi is that they have they have a double-strength product that can help cut down on the number of pills you need to take without additional any side-effects. Generally people take 1 tablet twice daily but it is individualized for every person.

Is Sodium Bicarbonate expensive?

Supplements like Bicarbi are inexpensive. One $20-25 bottle will last you 2-3 months depending on your dose. That’s far less than most people spend on one meal eating out.

Summary

Correcting and preventing metabolic acidosis is an incredibly important part of preserving kidney function. Simple strategies of increasing fruit and vegetable intake or taking a sodium bicarbonate tablet to decrease metabolic acidosis and can help in protecting your kidneys.

Want to know more or order sodium bicarbonate? Check out Bicarbi.com.

References

1. Di Iorio, Biagio R et al. “Treatment of metabolic acidosis with sodium bicarbonate delays progression of chronic kidney disease: the UBI Study.” Journal of nephrology vol. 32,6 (2019): 989-1001. doi:10.1007/s40620-019-00656-5
2. Shah, Samir N et al. “Serum bicarbonate levels and the progression of kidney disease: a cohort study.” American journal of kidney diseases : the official journal of the National Kidney Foundation vol. 54,2 (2009): 270-7. doi:10.1053/j.ajkd.2009.02.014
3. Raphael KL, Zhang Y, Ying J, Greene T: Prevalence of and risk factors for reduced serum bicarbonate in chronic kidney disease. Nephrology (Carlton) 19: 648–654, 2014 https://doi.org/10.1111/nep.12315
4. Raphael, KL. “ Metabolic acidosis in CKD: core curriculum 2019.” American Journal of Kidney Disease 74: 263-275, 2019. https://doi.org/10.1053/j.ajkd.2019.01.036
5. Goraya N, Simoni J, Jo CH, Wesson DE: A comparison of treating metabolic acidosis in CKD stage 4 hypertensive kidney disease with fruits and vegetables or sodium bicarbonate. Clin J Am Soc Nephrol 8: 371–381, 2013.
6. Phisitkul S, Khanna A, Simoni J, Broglio K, Sheather S, Rajab MH, Wesson DE: Amelioration of metabolic acidosis in patients with low GFR reduced kidney endothelin production and kidney injury, and better preserved GFR. Kidney Int 77: 617–623, 2010 
7. Goraya N, Simoni J, Jo CH, Wesson DE: Treatment of metabolic acidosis in patients with stage 3 chronic kidney disease with fruits and vegetables or oral bicarbonate reduces urine angiotensinogen and preserves glomerular filtration rate. Kidney Int 86: 1031–1038, 2014 
8. https://doi.org/10.3390/nu10040512
9. Scialla, Julia J, and Cheryl A M Anderson. “Dietary acid load: a novel nutritional target in chronic kidney disease?.” Advances in chronic kidney disease vol. 20,2 (2013): 141-9. doi:10.1053/j.ackd.2012.11.001
10. https://www.cdc.gov/salt/sodium_toolkit.htm
11. Al-Abri, Suad A, and Kent R Olson. “Baking soda can settle the stomach but upset the heart: case files of the Medical Toxicology Fellowship at the University of California, San Francisco.” Journal of medical toxicology : official journal of the American College of Medical Toxicology vol. 9,3 (2013): 255-8. doi:10.1007/s13181-013-0300-4
12. de Brito-Ashurst, Ione et al. “Bicarbonate supplementation slows progression of CKD and improves nutritional status.” Journal of the American Society of Nephrology : JASN vol. 20,9 (2009): 2075-84. doi:10.1681/ASN.2008111205
13. Jeong J, Kwon SK, Kim HY.  “Effect of Bicarbonate Supplementation on Renal Function and Nutritional Indices in Predialysis Advanced Chronic Kidney Disease.”   Electrolyte Blood Press. 2014 Dec;12(2):80-87.   https://doi.org/10.5049/EBP.2014.12.2.80
14. Hilton, Nathan Philip et al. “Enteric-coated sodium bicarbonate supplementation improves high-intensity cycling performance in trained cyclists.” European journal of applied physiology vol. 120,7 (2020): 1563-1573. doi:10.1007/s00421-020-04387-5