What would happen if you ate one sweet potato every day for 30 days? Well, let’s go ahead and jump right into this. The first thing that you would notice is a digestive benefit. I say this because the data demonstrates that it only takes one or two days to start noticing the digestive effects of a sweet potato. In fact, there was a study published in the journal Cancer Nursing that looked at leukemia patients going through chemotherapy. If you’ve dealt with chemotherapy before, you know those people deal with a lot of constipation and bowel issues. What they found is that adding 200 grams of sweet potato corrected their bowel issues in less than two days. Within two days, their constipation improved, and their digestion improved compared to the group that did not have the sweet potato. So the reason I mention this is because this is probably the quickest thing you’ll notice. When you’re talking just 200 grams of sweet potato, 80% of that is insoluble fiber, which is very potent when it comes to overall digestion.
But there’s a secondary effect that happens longer term as well. The cool thing is if you look longer term, there’s an interesting effect that happens when you consume sweet potatoes that’s independent of just the fiber. For this, we look at a study published in the Journal of Agricultural and Food Chemistry. It’s very interesting because they took the anthocyanins, the antioxidants in sweet potatoes, and treated gut bacteria with them. They noticed that the bad bacteria died off and the good bacteria flourished, ultimately resulting in more butyrate-producing bacteria. Butyrate-producing bacteria are the best kind of bacteria we can have in the gut. So with this, we’re in a really good spot. We have a short-term benefit when it comes to constipation and digestion, and a longer-term effect on the gut microbiome that’s completely independent of the fiber itself.
The next thing you might notice, maybe four or five days after having a sweet potato daily, is a reduction in joint pain and improvements in your complexion. The reason behind this isn’t just the fiber; it has more to do with the potent antioxidants in sweet potatoes, specifically anthocyanins. Anthocyanins are tremendous when it comes to reducing oxidative stress. Oxidative stress is the stress created from fuel metabolism, life, workouts, etc. It creates rogue electrons that circulate through our body and react with different things, causing stress and oxidation. Anthocyanins in sweet potatoes are one of the most potent antioxidants we can get in food. This manifests in how our skin looks and feels, and it reduces joint pain and inflammation.
If you start looking at recovery, such as trying to get more of a sport benefit or just a workout benefit, there was a study that looked specifically at this as well. This study was published in the Journal of Applied Physiology and had subjects run for seven days. They gave them either a high or low sweet potato polyphenol treatment and had them run at 70% of their VO2 max. They measured blood levels of oxidative damage, polyphenol content, and a couple of other things immediately after exercise and a few hours later. The results were pretty interesting. They found an increase in antioxidant capacity, meaning they had more antioxidants available, and dramatic reductions in oxidative stress, leading to better recovery. So that’s something you would notice probably inside of five to seven days if you’re working out a lot, getting sore, and not recovering well. A sweet potato might help you out, not because of the carbs or fiber, but because of the antioxidants.
The next piece you might notice might take more like a week to kick in, and that’s the memory and cognition benefit. The research here is pretty powerful. In the short term, you have improvements in spatial memory and working memory. Over the longer term, there’s prevention of cognitive decline, preventing neurodegenerative conditions. We look at a study published in Molecular Medicine Reports. It is a rodent model study where they took rats and induced a lot of neuroinflammation by giving them a high-fat diet. They divided the rats into three groups: high-fat diet, high-fat diet with sweet potatoes, and sweet potato diet only. The group that had the high-fat diet with sweet potatoes had protection against the inflammation from the high-fat diet. It reduced cyclooxygenase enzyme two, tumor necrosis factor-alpha, and interleukin-6, reducing brain inflammation associated with a bad diet. This suggests that sweet potatoes could be very protective against a somewhat bad diet, though I’m not suggesting you eat a terrible diet. Adding a sweet potato might help. They also saw increases in working memory, improving memory while protecting against inflammation.
A study published in Dementia and Neurophysiologia found that sweet potato extract protected the brain long-term, decreasing inflammation and increasing BDNF (brain-derived neurotrophic factor). This helps the brain produce more neurons and overall networks. By increasing BDNF, brain cells can literally grow more. Short-term, you’ll notice improvements in memory and cognition. Long-term, you might even get smarter.
As far as fiber and the brain are concerned, the more diverse our gut microbiome, the more impact it has on our brain. We have the gut-brain axis, where our gut communicates with our brain via multiple pathways, predominantly via the vagus nerve. A healthy gut means a healthy mind. Good fibers and antioxidants support good bacteria in our gut, helping maintain healthy serotonin levels and improving our mood and memory. This is why I always advocate for a diverse diet and a variety of fibers.
People often ask if a probiotic would help. The short answer is yes, especially if you’re making a dietary change. If you’re trying to positively impact your gut bacteria and haven’t been eating healthy for a while, it’s a good idea to add a probiotic to kick-start everything. I recommend a company called Seed, which offers a symbiotic with prebiotic fibers and probiotics. It has a capsule inside a capsule for proper staging, delivery, and potential colonization of bacteria. Their kids’ probiotic, PDS-08, is also interesting. You can save 15% off your entire order through Seed with the link below this video, top line in the description.
Between 7 and 14 days in, you might start noticing an improvement in your sleep. The data here is somewhat speculative, but we know the correlation between fiber and sleep. A more diverse microbiome can help you sleep, and more fiber can prevent blood sugar crashes that wake you up at night. It’s not the blood sugar crash itself but when your blood sugar goes low and your brain glucose goes low, the body produces adrenaline and cortisol to wake you up. More fiber in the diet helps prevent this. Sweet potatoes also provide enough of an insulin spike to help you sleep, as insulin allows tryptophan to enter the brain, converting into serotonin and then melatonin. Sweet potatoes are high in tryptophan, potassium, vitamin B6, and magnesium, all of which are crucial for melatonin production and calming the brain.
A longer-term benefit, noticeable 20-30 or even 60-90 days later, is cardiovascular health. A study published in the journal Life used hamsters on a high-cholesterol diet and gave them sweet potato leaf extract. The extract reduced overall cholesterol and LDL levels by 30-48%, decreased their atherogenic index, and increased antioxidant scores while reducing reactive oxygen species and oxidative stress. The researchers speculate that the antioxidants in sweet potatoes have a powerful effect on the cardiovascular system.
A 12-week study published in Diabetes Care found that subjects who had just 4 grams of sweet potato daily for 12 weeks had significant reductions in HbA1c, fasting glucose, and two-hour postprandial glucose. This suggests that sweet potatoes can be beneficial for metabolic health, even though they are relatively high on the glycemic index. The antioxidants in sweet potatoes provide some amnesty, making them a good option for a low-carb diet, especially if eaten at night.