Exogenous ketones supplements dissolved in water - by Doug Cook RD

Pruvit Keto OS. Should You Try These Products?

Ketone supplements in water - Pruvit Keto OS. Should You Try These Products?

The ketogenic diet is as hot as ever.


It’s a low carb, high fat diet that has been associated with many health benefits, but mostly leveraged for weight loss (1).


Nutritional ketosis (ketosis), not to be confused with ketoacidosis, is a normal metabolic state. Ketoacidosis a serious complication that can happen in those who use insulin to manage diabetes. The two are very different; apples to oranges.


As a dietary manipulation, ketosis is achieved by following a very low carb, high fat ketogenic diet (2). As a result, ketones are produced and used by your body in different ways.


Naturally, it was only a matter of time before ketone supplements hit the market. They’re advertised as offering the same benefits of a keto diet even if someone isn’t on a ketogenic diet or in nutritional ketosis.


Pruvit Keto OS is one such brand. As ketone supplements, they’re promoted to “optimize cellular regeneration, energy and longevity, increase energy and reduce appetite”. This review will specifically take a look at Pruvit Keto OS supplements and explore any evidence surrounding exogenous ketones.

What are ketones?

Ketones (a.k.a. ketone bodies); everybody has them. These compounds are produced by your liver as an alternate energy source when glucose is unavailable for fuel (2). This happens to some degree everyday, even without being on a ketogenic diet.


Any carbohydrate eaten at a meal will be digested and used within a couple of hours, give or take. Once this happens, blood sugar and insulin levels will be on the lower side – this is normal. However, your cells and tissues still need energy, so what’s a liver to do? Produce ketones!


Normally, ketones are produced at different rates depending on how long it’s been since your last meal. Ketone production starts to increase, leading up to your lunch and dinner time provided it’s been 4 or more hours since eating. Once you eat, ketone production shuts off and your body will use glucose and fat from your food.


Ketone production is greatest after an over night fast; between the 10 to 12 hours between dinner and waking up. Ketone production during this time is typically at the rate of 0.2-0.4 mmol/min (3).

Ketone production during fasting

Ketones production really takes off during periods of prolonged starvation and fasting. During a fast, there’s no food (and therefore carbohydrate) intake forcing the body to find another energy source. As point of comparison, by day 5 of a fast, ketone production increases to 1.5-2.5 mmol/min; a 4 to 5 fold increase in production. As well, ketone blood concentrations rise 40 to 50 fold (3). But, you don’t have to be in a prolonged fasting state only.


Dietary carbohydrate restriction will also increase ketone production because the liver won’t have a steady supply of glucose. In fact, this is the very premise behind a ketogenic diet. Without glucose, the liver takes fat and converts it into ketones which the cells of your body use as energy.


Ketone bodies 300x300 - Pruvit Keto OS. Should You Try These Products?


The ketones made during ketogenesis are acetate, acetoacetate and beta-hydroxybutyrate [same as 2-hydroxybutyric acid] (4).


This brings me to a point of clarification for the purposes of this review. There are two types of ketones of interest:

  • Endogenous ketones: these are the ones just described. Those that are produced by the liver during times of fasting, or dietary carbohydrate restriction
  • Exogenous ketones: as the name implies, ketones from an external source, in this case as nutritional supplements.

Most exogenous ketone supplements, including Pruvit Keto OS, use beta-hydroxybutyrate [BHB] because it’s the ketone that’s used most efficiently by the body; why would you want to use a less efficient one right? (5).


The real question one everyone’s mind is: “can exogenous ketones offer the same metabolic effects as a ketogenic diet”?

What exactly are Pruvit Keto OS supplements?

Simply put, Pruvit Keto OS supplements are exogenous ketones that are taken as a drink. They’re offered in different flavours with the choice of being caffeine-free or “charged” (code for, added caffeine).


Their products range in price from $88-$138 USD per package of 20. In other words, $4.40-$6.90 per serving. For my Canadian readers, that’s about $116-$182 CAD per box or $5.80-$9.10 per serving. They also sell it in bulk form which will be a little cheaper on a per serving basis. Phew!


Given that they recommend 1 to 2 servings per day, you can see how long (as in not) a package of the Pruvit ketone supplements will last……and cost.

What’s in a serving of Pruvit Keto OS?

Keto OS NAT and Keto OS MAX

Pruvit uses ketone salts in their products where ketones are compounded with calcium, sodium and potassium. One serving has:

  • 50 calories
  • 5 g carbohydrate (4 g as sugar alcohol)
  • 50 mg vitamin B6
  • 100 mcg vitamin B12
  • 270 mg calcium
  • 910-930 mg sodium
  • 70 mg potassium
  • Ketone blend 12.6 g*
    • Beta-hydroxybutyrate (BHB)
    • Taurine
    • Leucine
    • C-Med 100 (cinnamon essentially)


*The actual amount of BHB is not indicated.


Keto KREME FFT one serving has:

  • 130 calories
  • 12 g fat
  • 3 g carb
  • 2 g protein
  • 5 mg vitamin B6
  • 100 mcg vitamin B12
  • 130 mg calcium
  • 70 mg sodium
  • 40 mg potassium
  • NT Bioavailability Blend 18.4 g
    • Coconut shortening powder
    • MCT powder
    • TendoGuard (Collagen Types I, II, V, X)
    • C-Med 100 (cinnamon essentially)


Ketone urine test - Pruvit Keto OS. Should You Try These Products?How do Pruvit Keto OS supplements work?

Pruvit acknowledges that it can take several weeks for someone to move into, and adapt to ketosis when using a ketogenic diet.


A traditional keto diet is comprised of about 5% carb, 15-20% protein and 75-80% fat. The diet can be hard to follow for a couple of reasons not the least of which are limited food choices when you don’t have the luxury of preparing your own food.


But, there’s hope. According to one of Pruvit’s specialists on their website (see videos), their exogenous ketones “elevate your blood ketone levels as if you were in nutritional ketosis but without having to follow the strict guidelines of being on the ketogenic diet”.


On a ketogenic diet, ketone levels slowly increase over time until they reach a relatively steady state. But with an exogenous ketone supplement like Pruvit Keto OS, ketones levels rapidly (6). Pruvit states that within 60 minutes, serum ketones rise to a level that’s equivalent to being in nutritional ketosis. Levels remain elevated until the ketones leave the body within 3 to 6 hours as you pee them out.


The difference here is that with supplements, the level of ketones ebbs and flows. If you take it twice a day, you have them in your blood for about 12 hours; 6 hours in the morning until noon, and them from late afternoon until before bed for example. On a ketogenic diet, ketones are elevated 24/7. Diet-induced ketones are also peed out.


Obviously the attraction of supplemental ketones is that they can raise blood levels of ketones without being in a state of ketosis. Pruvit endorses this idea, that you “don’t have to change your diet to experience the benefits of having ketones in your system”. Is that true?

What about those specific claims?

The Pruvit website is rife with fantastic claims:

  • Keto OS NAT: “supports healthy cell function, rapidly repairs DNA, boost immune function and elevates essential amino acids necessary for optimizing body composition”.
  • Keto OS MAX: in addition to the above, “delivers advanced macronutritionals and promotes optimized cellular regeneration, energy and longevity”.
  • Keto KREME FFT (Functional Fat Technology): “increased focus, improved cellular repair, assists the body to repair damaged DNA and cellular structures, stimulates collagen synthesis, strengthens hair and nails, maintains healthy joint mobility, restore and balance digestive health naturally with antimicrobial nutrients and caprylic fatty acids”.


The problems with these claims is that Pruvit can’t prove it but rather has taken elements of truth and exaggerated them. By listing these benefits, they are actually making functional claims for their products. In doing so, they had better be prepared to back them up with evidence.


For example, Keto OS NAT contains leucine, an essential amino acid that IS involved in muscle protein synthesis. They then use this fact, and make the claim that Keto OS NAT will elevate the level of an amino acid “necessary for optimizing body composition”. A reasonable interpretation is that this particular product will in fact, improve body composition. Really?


Or, with Keto KREME FFT, the claims are even more fantastic. It’s true that dietary collagen is a source of glycine, an amino acid that your body will use to make its own collagen. Thing is, the amount of collagen and by extension, glycine, in this product is infinitesimally small. Too small to make a dent in the estimated minimum 10 g of glycine per day that the modern diet is lacking. Keto KREME is not going to strengthen your nails and hair, nor will it help your joints.


The suggestion as well that the amount of caprylic acid found in the Keto KREME is enough to provide antimicrobial properties is questionable.

Appetite suppression

During nutritional ketosis that comes from a ketogenic diet, ketone bodies are powerful appetite suppressants. Keto OS claims to do the same. By keeping hunger at bay, Keto OS NAT and Keto OS MAX should help control snacking, possibly overall intake, and weight management. But where’s the evidence that their product has been studied for this claim?


Where Pruvit Keto OS misleads is by citing good quality research on the benefits of ketogenic diets along side their products which leads us to believe that their products, by extension, can do the same. Knowing this, they also provide the caveat  “under no circumstance is the information contained within such third party research to be used or considered as a direct or indirect study of any Prüvit product”.


They’re also legally required to include a CYA [cover your ass] disclaimer “these statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease”.


Sadly, some Pruvit reviews stop there and have categorically dismissed the idea of supplemental ketones because of these claims but is there more? I’m always compelled to go deeper; to do my due diligence.


Keto diet word cloud - Pruvit Keto OS. Should You Try These Products?


Pruvit ketosis. Is it possible?

Whether it’s Pruvit or another brand, what everyone is really wondering is, are exogenous ketones capable of putting someone into ketosis? In this case, Pruvit ketosis :). The stumbling block for most, and rightfully slow, is the idea that just as effective.


Those who’ve tried the products and who tested their urine using ketone test strips found that they were in fact, not in ketosis.


But that’s not what Pruvit is claiming.


They’re claiming that you can raise blood ketone levels as if you were on a ketogenic diet. That you don’t have to change your diet to experience the benefits of having more ketones in your body.


So the question is really whether or not the presence of ketones in the blood, at a sufficient concentration, is what matters versus how those ketone bodies were elevated; fasting/low carb versus supplements?

Are exogenous ketones effective?

This is where the devil is in the details. Exogenous ketones come in two main forms: ketone salts and ketone esters. While both have been shown to raise blood ketone levels, they don’t raise them equally.


Studies using ketone salts resulted in blood levels of BHB of about 1 mmol/L. Ketone esters on the other hand resulted in BHB is the 3-5 mmol/L range (6, 7, 8, 9).

Not to be confused with ketogenic diets

As stated, ketogenic diets result in sustained elevated levels of ketones versus and ebb and flow from using supplements.


Recommended blood ketone levels varies but most experts in the field recommended 0.5-3.0 mml/L. “Light” nutritional ketosis is in the 0.5-1.5 mmol/L range with 1.0-3.0 mmol/L being “optimal”.


To put this in perspective, during a fast where there’s no food, ketones can get up to the 3.0-8.0 mmol/L range.

Ketogenic research

Casual visitors of the Pruvit Keto OS site might understandably confuse supplemental ketones and the effects of ketogenic diets as being equal.


The site’s videos and reps talk about the benefits of ketones, how their products increase blood ketone levels and how using their products will provide the same results of a ketogenic diet without the effort; or at least that’s heavily implied.


The navigation menu has a “Learn” section with a “research” sub menu. Once you scroll down past the product marketing, they list heaps of research on ketogenic diets for various health issues but nothing on their products or similar products.


It’s a bit of a stretch (false) and misleading to give the impression that their product is on par with a legit ketogenic diet without proof.

Ketone supplements. What’s the evidence?

Here, the evidence is interesting. It’s worth noting that results WILL depend on whether or not ketone esters were used versus ketone salts.

Reduced appetite: a study of 15 people found that those who consumed 1.9 calories of ketone esters per kg of body weight, had significantly less hunger and desire to eat compare to placebo. Hunger hormones like ghrelin and insulin were also lower in the ketone ester group (10).


Athletic performance: some research has shown a possible benefit from exogenous ketone esters when it comes to performance. Thirty-nine athletes were given 260 mg of ketone esters per pound of body weight (573 mg/kg) during exercise. Those who took the supplement travelled about 400 m (1/4 mile) farther over 30 minutes compared to those who drank a beverage with only carbohydrate and fat (11).


Is Keto Good For Athletes? Part 1


Cognition: some research has found a cognitive benefit from increasing ketone production via the metabolism of MCT oil with some research suggesting a benefit for Alzheimer’s disease (12, 13, 14).

Ketone molecule structure - Pruvit Keto OS. Should You Try These Products?Are exogenous ketones safe?

From what can be determined, they are completely safe but not without some drawbacks:

  • Digestive – issues such as stomach upset, bloating, gas and diarrhea (15).
  • Bad breath – like with a ketogenic diet. The ketones in the blood pass through the blood vessels in the lung and are exhaled via breath (16).
  • Expensive – as noted above. At 2 per day, it will run you $207 USD or $272 CAD per month.
  • Taste – awful according to those that use the products; ranging from sickly sweet to synthetic

The reality is, exogenous ketones/ketone supplements are new. There is simply not a long of research on them. Also new is the combining of a ketogenic diet with ketone supplements. The additive, long term effects just aren’t know and rather impossible to predict at this time,

Bottom line

The use of exogenous ketones as a supplement is very new relative to the use of other products like vitamins, minerals, protein powders and amino acids.


Although there is some evidence that exogenous ketones may be beneficial for appetite suppression, brain energy metabolism in Alzheimer’s disease and limited benefit with exercise, it’s really at the theoretical/hypothetical level.


High level evidence via well-designed studies that have been blinded and properly powered to find outcomes we can be confident with simply doesn’t exist. This may change in the future with ongoing research.


When it comes to benefits from elevated blood ketones, there’s a lot of good data from nutritional ketosis, either from intermittent fasting, or low carb, high fat diets based on nutrient-dense foods that provide high quality fats, phytonutrients from lower-starch vegetables with adequate vitamins and minerals.


Due to the high cost and overall reputed poor taste, Pruvit Keto OS supplements might not be worth the cost. The problem is, you likely couldn’t draw any meaningful personal conclusions from a carton of 20 servings (a 10 day supply). And, I suspect you don’t have 200 plus bucks a month to spend to find out if a long trial is worth it. It would be better to put that money toward some good quality food, and experiment with a ketogenic diet instead. At least there’s evidence for that.


The jury is still out on whether ketone supplements are the way to go. What is certain though, is that Pruvit Keto OS cannot back up the fantastic claims they make about their products no matter how enticing they may seem.


Doug Cook RDN is a Toronto dietitian and functional nutritionist with a focus on digestive, gut, mental health.  Follow me on FacebookInstagram and Twitter.

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