Last week, I explored the impact of all the various foods, beverages, and food-like substances people consume while fasting—and hoping to maintain a functionally fasted state in the post, “The Definitive Guide To What Breaks a Fast.” Does MCT oil break the fast? What about coffee, tea, or bone broth?
There were more than a dozen, and I even did a follow-up. Today I’m going to discuss whether commonly-consumed supplements break the fast.
A popular one I’ve seen around—Alive, made from kale and raspberries—has just 2 grams of carbs per dosing. It’s not ideal, but it’s not a deal breaker—or a fast-breaker.
Gummy vitamins have the potential to be about 5-6 grams of sugar, a gram of protein (from gelatin), and a gram of fat (if including omega-3s) per serving, so they’d arguably break the fast. Plus, they taste like candy and are likely to stimulate cravings and make fasting harder.
Gummy vitamins break the fast.
Potassium is non-caloric and does not break the fast. In fact, it can help you handle the fast better by replenishing electrolytes.
If you’re strict and technical, then yes, collagen breaks a fast. There’s evidence that glycine—the most prominent amino acid in collagen—can inhibit autophagy, but it was a convoluted animal study where inhibiting autophagy with large doses of glycine after brain injury actually improved outcomes. It probably doesn’t apply to someone adding a scoop of collagen to their coffee. Besides, even if it slightly reduces autophagy, a little collagen won’t negatively impact ketosis, fat-burning, or energy intake.
I’m going to say “technically yes,” but “realistically no, collagen doesn’t break the fast.” Avoid if your main focus is autophagy, however.
Branch Chain Amino Acids (BCAAs)
BCAAs trigger an insulin response and thus stop autophagy…and the fast. That said, many proponents of fasted training recommend using BCAAs before a workout to help preserve muscle and improve the post-workout anabolic response.
I’m going to say “yes, BCAAs break the fast.”
Vitamin D is fat soluble and thus comes packaged in an oil carrier, but the dosage is so small that it won’t affect your fast.
Unless you find that 1/8 teaspoon of olive oil ruins your fast, vitamin D won’t break a fast.
Probiotics contain no calories and will not break a fast. However, they are best absorbed in the presence of food—the food protects them as they travel through the digestive system, and most probiotics occur naturally in food—so taking them during a fast is probably, mostly useless.
Probiotics don’t break a fast, but why take them during one?
Pure prebiotics will not break a fast, as they contain no digestible carbohydrates. Prebiotic-enriched foods will break a fast, as they do contain calories.
Adaptogens are compounds, usually herbs or herb derivatives, that modulate your stress response. They improve your ability to tolerate and respond to stressful situations; they don’t blindly inhibit the stress response if the stress response is warranted. They keep you honest and counter unnecessary stress responses. They contain no calories, unless you’re chowing down on a big hunk of maca or ashwagandha root. In fact, most adaptogens have traditionally been consumed in tea form, extracting the active compounds and leaving behind any calories. Have at ’em.
Adaptogens do not break the fast.
Medicinal mushroom extracts come from mushrooms, which are technically food. But the amounts you take are so low—usually no more than a teaspoon—that they won’t impact your fast or provide any significant amount of caloric energy. Four Sigmatic has those “mushroom coffee” blends you add to hot water. They can get up to about 30 calories per serving, but even that’s going to let you maintain most of the fasting benefits.
Mushroom extracts don’t break the fast.
I used to keep the old Trader Joe’s melatonin on hand because it was half a milligram, whereas most other melatonin supplements are in the 3-5 mg range. It was also sweet, tasting like those white Valentine’s Day mint hearts you used to get back in the day. I haven’t come across any sweetened melatonin supplements since Trader Joe’s phased those out, but that’s the only thing I’d worry about on a fast.
Melatonin does not break a fast.
Final Note: Most supplements are okay to take on a fast, though the lack of food may make absorption more difficult. If you have any other questions about supplements on a fast, drop them down below. Thanks for reading, everybody.
Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.