The sports supplement market is big business, but the reality is that most of these supplements have little evidence for a benefit. It is not all negative news though because there is a small group of supplements that are backed by science and which can play a performance-enhancing role in some athletes. In this series on sports supplements, I will profile this group of supplements and for this podcast, the spotlight is on sodium bicarbonate. 

Sodium bicarbonate may sound like something straight out of a Russian sports-performance laboratory, but you’ve been around and eating sodium bicarbonate all of your life. In fact, I’m pretty sure you’d have some in your pantry. It’s good old baking soda. This all-purpose kitchen chemical is handy in the leavening of bread, as an antacid to calm a flare-up of heartburn, and it also makes a great cleaning and scouring agent. It is also an effective sports supplement.

During short-term, high-intensity activity, lactic acid, hydrogen ions and carbon dioxide accumulate in the blood and muscles. While most of the by-products are buffered, some do remain in the muscle cells and create an acidic environment. Increased acidity alters pH levels, causing our muscles to burn and feel fatigued – the classic ‘burn’ you feel when you’re pushing yourself in the red zone for too long.

Enter the role for sodium bicarbonate as an all-purpose buffer and alkaline base. Afterall, bicarbonate is already naturally present in your body as a key pillar of the body’s acid-base regulatory system. Bicarbonate buffers excess acid that accumulates during high intensity exercise and neutralises the carbon dioxide, thereby maintaining muscle pH levels closer to normal and enhancing exercise capacity. This opens up the potential for sodium bicarbonate in having a benefit on sustaining high-intensity exercise performance.

In fact, sodium bicarbonate was one of the few supplements to get an endorsement for having good evidence behind it in the 2018 IOC Consensus Statement on dietary supplements for use by high-performance athletes and I’ll link to this document in the show notes https://bjsm.bmj.com/content/52/7/439

So, let’s go over a summary of those benefits. Sodium bicarbonate is seen to enhance performance in the range of about 2 percent in short-term, high-intensity sprints lasting about 1 minute in duration. The benefit does drop off if the exercise effort exceeds about 10 minutes. So, the sweet spot for using sodium bicarbonate is for 1 to 7 minutes of high intensity exercise such as swimming, rowing and middle distance running.

There are plenty of places to get hold of sodium bicarbonate. Sodium bicarbonate supplements can be found in capsule or tablet form or your classic baking soda will also do the job.

So, how much do you need and what is a classic loading protocol to take it? For acute loading 1-2 hours before an event, bicarbonate can be taken at a dose between 0.2 and 0.4 grams per kilogram of body weight together with 1-2 litres of water to reduce risk of gastrointestinal problems.

Alternatively, it can be taken as part of a chronic loading protocol at a dose of about 0.5 grams per kilogram of body weight, split into 3-4 doses spread over the day. And doing this loading for 2 to 4 consecutive days before an event. Chronic loading achieves an increase in blood buffering capacity that is maintained for at least 24 hours after the last dose and presents less risk of gastrointestinal side-effects.

As a side note here, showing that large doses of sodium bicarbonate can improve sports performance by acute effects in the local area of the muscle is not some form of endorsement to the crazy that is the alkaline diet fad. 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 which can result in death. The body keeps blood pH in a very tight range. Food though can change urine pH 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 has no effect on the pH of any other part of your body.

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 pH, but instead deflect this to the stress acidic foods place on the body from the need to buffer the pH against the acidity which is harmful. 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 that pH differs all throughout different body compartments. You want a very acidic stomach and slightly acidic mouth/saliva to help with food digestion. While a lower pH in the colon from bacterial fermentation is linked to favourable changes in disease risk profile. An alkaline diet 'works' because it gives a person a selective list of foods to eat and avoid which means lots of vegetables and less highly processed food. That's it. Okay, rant over.

Side effects

Sodium bicarbonate is one supplementation that you don’t want to use without trialling it many times in your training. It certainly can cause unpleasant gastrointestinal side effects such as  diarrhoea so should be used under supervision and practised in appropriate training sessions to assess benefits and side-effects.

Strategies to minimise gastrointestinal upsets include taking it with a small, carbohydrate-rich meal, trialling sodium citrate as an alternative, or using split dosing.

Also, it is theoretically possible to induce a state of metabolic alkalosis with sodium bicarbonate which is just as dangerous as acute acidosis, so you should not exceed recommended dosages. Sodium bicarbonate also should not be used in people with impaired kidney function without the supervision of a medical doctor.

Sodium bicarbonate is one of the few nutritional supplements for which research has consistently shown a sports performance benefit. The use of all supplements and sports foods by athletes though involves a balance between the potential benefits set against potential risks such as health side-effects, anti-doping rule violations from contamination, and redirection of resources from real performance-enhancing factors. So, take this into account when considering taking any sports supplement. And seek out personalised advice from a sports dietitian. You can connect with an Accredited Sports Dietitian as well as access a great range of resources through the website of Sports Dietitians Australia at www.sportsdietitians.com.au

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.