I got my COVID vaccine booster last week. As with my previous two COVID vaccines, I got the standard side-effects:
Soreness at the injection site
Fatigue
Headache
Muscle soreness
Fever
Chills
High blood sugar
These started about 5h after getting the vaccine and lasted ~24h, the same as the last two times.
In addition to the standard effects, when I woke up the day after getting the vaccine, I noticed that my heart rate was 100 bpm, 21 bpm higher than average and way outside my normal range (see Figure 1).
Figure 1. Pulse upon arising over the last 4 months, measured by Omron blood pressure monitor. Reference lines & bands were calculated for data prior to the vaccine.
Intrigued by this, I decided to track by pulse over the course of the day using my Omron blood pressure monitor. My original intention was to measure every hour, but I skipped several measurements where either my arm was sore at the measurement site or where I fell asleep. I had also wanted to track my temperature, as that’s known to correlate with increased heart rate1, but my family had taken our thermometer for the day.
As can be seen in Figure 2, my pulse peaked shortly after waking up, then declined steadily throughout the day, ultimately returning to about normal by the next morning. This corresponded to my subjective assessment of how I was feeling. I felt the worst when I woke up, got steadily better over the course of the morning with an abrupt improvement when I took a nap around 2pm (waking at ~4p), and felt completely fine when I woke up the next day.
Figure 2. Pulse vs. time the day after receiving vaccine, measured by Omron blood pressure monitor.
Although vaccine side effects have been widely reported, I couldn’t find much on the effect on heart rate. The only paper I found was a medRxiv paper from Quer et. al. at Scripps, which reported a small but statistically significant increase of 1.5 bpm after the second dose of the Pfizer or Moderna vaccine for a population of 3,300, with heart rate peaking on the day after vaccination and returning to normal by day 6. This is a much smaller effect size and longer duration than I saw, but there are some critical differences:
They’re averaging a large number of people and there may be significant person-to-person variation in the effect.
They report average the heart rate over the course of the day, while I report individual time points.
They used data from Fitbit or Apple Watch vs. a blood pressure monitor.
To check the last two factors, I plotted the heart rate data from my Apple Watch (see Figures 3 & 4). Unfortunately, the watch had not recorded my data for 4 out of the 5 days prior to my vaccination (no idea why), though there was nothing unusual in my routine those days.
As can be seen from the graphs, the day after getting the booster vaccine, my arising and awake pulse were 27 and 13 bpm higher than average, respectively. This is consistent with the 21 bpm rise observed with the Omron and much higher than that observed by Quer et. al.. However, using the watch data, I do see the longer recovery time (~6 days) reported by Quer et. al. Not sure why I didn’t see this with the Omron, but it could be related to the fact that I don’t use it as often, resulting in a higher uncertainty in the average value.
Figure 3. Pulse upon arising over the last 4 months, measured by Apple Watch. Reference lines & bands were calculated for data prior to the vaccine.Figure 4. Pulse while awake over the last 4 months, measured by Apple Watch. Reference lines & bands were calculated for data prior to the vaccine.
This strongly suggests I’m actually seeing a larger effect and the result of different measurement methods. Anecdotally, I had worse side effects from the vaccine than most people I’ve spoken with, which is consistent with the larger increase in heart rate.
Have any of you seen an increase in heart rate from the COVID vaccine? If so, let me know in the comments.
This week in my low-carb food study, I have Reader Requests!
For the past 6 weeks, I’ve been posting a series of studies on the blood glucose impact of low-carb foods (tortillas, cereal, ice-cream, bread). In the comments for each of these posts, I’ve been getting some great recommendations for other foods to try, so I decided to do a “Reader Requests” study where I measured the BG impact of the recommended foods.
The results were really interesting. In every category, there was a Reader Request that either had a much lower BG impact than what I had found or gave significant insight into the BG impact of different ingredients.
Here’s what I found:
Summary
Tortillas
The regular flour tortillas were much lower impact than I expected (30% peak BG & 70% iAuC vs. glucose), similar to that of the resistant wheat starch tortillas. This makes the resistant starch tortillas look even worse than I originally thought. Definitely never going to eat those again.
Neither of the recommended low-carb tortillas (Mr. Tortilla & A La Madre) beat out La Tortilla Factory for taste, texture, and BG impact, so I’m going to stick with La Tortilla Factory for personal meals.
Ice Cream
All three of the requested low-carb brands had lower BG impact than any of the brands I’d previously tested. The Two Spoons brand, in particular, was extremely good and has the only fruit-flavored low-carb ice cream I’ve seen. The Two Spoons Strawberry and Brownie Fudge flavors are my new favorite by a pretty wide margin.
Breads
The Julian Bakery breads were very low carb, but didn’t taste much like regular bread. They were interesting, but if I’m looking for a bread replacement, I’d pick something else.
Yogurt
Two Good Strawberry Yogurt had good texture and low BG impact, but the flavor was too mild and had a stevia aftertaste I didn’t like.
I would prefer to eat their plain yogurt and add my own mix-ins, maybe some nuts or chopped chocolate for a dessert.
Note: Readers also recommended several of the best breads that were included in the original bread post, including: Carb0naut (Can’t find the original request, sorry), Unbun Unbread (u/fawkesandholly, u/Impressive_Citron_84), Kiss My Keto (u/justjules83), and Base Culture (u/Spell_Chick).
If there’s anything else you want to see me test, please let me know in the comments.
– QD
Details
Tortillas
Tortillas tested. New requests in orange.Blood glucose impact of tortillas.
Summary: Nothing spectacular here, but the Mr. Tortilla could be good if you prefer smaller size tortillas/soft tacos.
La Tortilla Factory Flour Tortilla (not low-carb, as a control) (Can’t find the original request, sorry)
Much lower impact than I expected (30% peak BG & 70% iAuC vs. glucose), similar to that of the resistant wheat starch tortillas. This makes the resistant starch tortillas look even worse than I originally thought. Definitely never going to eat those again.
About the same BG impact as the regular flour tortillas (23% peak BG & 63% iAuC vs. glucose). Not great and not consistent with the claimed net carbs.
Taste was only ok, too. Will not use again.
Mr. Tortilla 1 Net Carb Tortilla (Can’t find the original request, sorry)
About the same BG impact as the best-in-class La Tortilla Factory tortillas (14% peak BG & 40% iAuC vs. glucose, or about half the LTF flour tortillas)
I didn’t like the taste as much as the LTF low-carb tortillas (bit too gritty), but they’re taco sized, which is very convenient for some recipes.
All-in-all, I found these to be ok, but will continue to buying the La Tortilla Factory low-carb tortillas going forward
Ice Cream
Ice cream tested. New requests in orange.Blood glucose impact of ice cream per gram.Blood glucose impact of ice cream per gram, zoomed in to only show low-carb ice creams.Blood glucose impact of ice cream per cup, zoomed in to only show low-carb ice creams.
Summary: All three of the requested low-carb brands had lower BG impact than any of the brands I’d previously tested. The Two Spoons brand, in particular, was extremely good and has the only fruit-flavored low-carb ice cream I’ve seen. The Two Spoons Strawberry and Brownie Fudge flavors are my new favorite by a pretty wide margin.
Talenti Double Dark Chocolate (not low-carb, as a control) (Can’t find the original request, sorry)
BG impact was consistent with the carb count (peak BG 27% of glucose, total carbs 31% of mass), and way higher than any of the keto brands. Not surprising.
Lower BG impact than any of the original brands I tested (2.0% peak BG & 5.5% iAuC vs. glucose)
Much harder texture out of the freezer than heavy cream-based ice cream. Even after sitting out for 35 min., I had to microwave it to get to my desired softness.
Had a strong chocolate and coconut taste. A lot lighter/airy than the heavy cream based brands, but still had a “creamy” texture.
Overall, I didn’t like it as much as the other brands, but I could see some people preferring it.
Lower BG impact than any of the original brands I tested (2.5% peak BG & 5.9% iAuC vs. glucose)
Softest texture of any of the brands. This and Two Spoons were the only keto ice creams that could be “scooped” straight from the freezer.
The Coffee Karamell flavor is more mild than I’d like, but it’s ok. I’d really like to try some of their other flavors, but this is the only one in my grocery that’s low-carb.
Way lower calories than other brands (240 kcal/pint vs. 470-680 kcal for other brands). Not sure why, though maybe it’s got a higher water content with more stabilizers & emulsifiers to soften.
Warning: The nutrition label on their website doesn’t match with what I found in the store. The BG impact matches up with the label, so if you’re buying this, make sure you read the label carefully.
The lowest BG impact of any ice cream I’ve tested:
Chocolate: 1.8% peak BG & 4.2% iAuC vs. glucose
Strawberry: 2.0% peak BG & 4.9% iAuC vs. glucose
This has the most similar texture to regular ice cream of all the brands I’ve tried. Scoopable, but a bit hard straight from the freezer. 1 min. in the microwave at 30% power got it to my preferred texture.
The chocolate flavor was good, though I’d prefer a stronger flavor.
The strawberry was amazing. Extremely smooth, creamy taste and the strawberry mix-ins taste like firm strawberry jam. This is the only keto fruit flavored ice cream I’ve found. I’ve always preferred fruit-flavored ice-creams and this was a great example.
I also tried their Brownie Fudge & Coffee Toffee flavors, but didn’t do a BG test
Brownie fudge: My second favorite after strawberry. A stronger chocolate flavor than chocolate and the brownies gave a nice flavor and textural contrast (even stronger chocolate flavor & soft chewy texture).
Coffee Toffee: Very strong coffee flavor with a great texture contrast from chocolate chips and toffee. If you like coffee ice cream, I’d definitely recommend it.
Breads
Bread tested. New requests in orange.Blood glucose impact of bread.
Summary: The Julian Bakery breads were very low carb, but didn’t taste much like regular bread. They were interesting, but if I’m looking for a bread replacement, I’d pick something else.
Julian Bakery KetoThin Bread (Can’t find the original request, sorry)
The lowest BG impact of any of the breads I’ve tested (3% peak BG & 8% iAuC vs. glucose)
This one was a bit odd. It was soft, moist, and tasted pretty good, but not at all like bread. You can really taste the cream cheese in it.
When toasted or fried, it became slightly crispy and the cream cheese taste was much less noticeable.
Julian Bakery PaleoThin Sandwich Bread (Can’t find the original request, sorry)
3rd lowest BG impact, after Julian Bakery KetoThin & UnBun UnBread (6% peak BG & 10% iAuC vs. glucose)
The bread was a little wet when I opened it and tasted slightly sour. Taste was not that great, though maybe it was starting to spoil? I ate it right after opening the sealed package and 3 days after it arrived, so if it was spoiled, that’s not a good sign.
Yogurt
Blood glucose impact of Two Good Strawberry Yogurt.
Low BG impact (4% peak BG & 7% iAuC vs. glucose), a little higher than its net carb count (2% of mass)
Strawberry flavor is very mild and has a stevia aftertaste that I don’t like.
Texture is great, creamy and not chalky like some greek yogurts
I didn’t like this and would prefer to eat their plain yogurt and add my own mix-ins, maybe some nuts or chopped chocolate for a dessert.
Design/Methods
Foods. Full nutrient and ingredient info here. Key nutrition facts in the tables in above.
Procedure. At 5:00a, I took 4.5u of Novolog (fast acting insulin, duration of 2-4h), then drank a Ketochow shake (website, BG testing) at 5:30a. After that, no food or calorie-containing drinks were consumed and no exercise was performed. Non-calorie-containing drinks were consumed as desired (water or caffeine-free tea). At 10:30am-12 pm, the substance to be tested was eaten as rapidly as comfortable and notes on taste and texture were recorded (before observing any change in blood sugar).
Blood sugar was monitored for 5h using a Dexcom G6. Calibration was performed 15-30 min. before the start of each experiment.
Separately, all breads were toasted using a Brava oven (wheat toast, setting 7). Taste and texture were recorded.
Data Processing & Visualization. iAUC was calculated using the trapezoid method (see data spreadsheet for details). Data was visualized using Tableau.
Medication. During these experiments, I took long-acting basal insulin each evening at 9pm (Lantus, 1.5u) and 2000 mg of metformin and multivitamin each morning at 5am. I did not dose for the experimental food ingested.
About a week ago a reader, /u/genetastic, reached out about collaborating on experiments to determine the effect of vinegar on blood glucose after meal consumption.
Like most of you, I had heard all the nigh-magical, pseudoscience claims about using apple cider vinegar to treat diabetes. However, when you dig into the literature, there’s a sizable number of peer-reviewed studies, including several decent meta-analyses, showing that consumption of vinegar with a meal can reduce the blood glucose impact in both diabetic and non-diabetic subjects (see background below for details). There’s also a lot of open questions, including:
Is the effect large enough to matter for practical meals?
What types of meals does vinegar affect?
What is the best protocol to get a large effect without unpleasant side effects?
What’s the underlying mechanism?
Is the effect specific to vinegar or do other acids work?
/u/genetastic, a third collaborator /u/kabong, and I decided to answer these questions with community self-experiment.
Below, I give more details on the background literature and pre-register our protocol and analyses.
It would significantly improve the study to have a larger number of participants. If you’re interested in collaborating on this or other scientifically rigorous self-experiments with low-carb foods, supplements, or other health interventions, please let me know in the comments or via the contact form on the right.
Details
Purpose
To replicate (or fail to replicate) the existing literature and quantify the effect of vinegar on blood glucose level after consumption of complex carbohydrates.
To better understand the underlying mechanism by determining how this effect varies with person/metabolic status, dose, source of calories, and type of acid.
Figure 1. Forest plot showing individual and pooled random effect standard mean difference (95% CI) of trials testing the effect of vinegar on glucose area under the curve. Test of overall effect: z = 2.42, p = 0.01.Figure 2. Forest plot showing individual and pooled random effect standard mean difference (95% CI) of trials testing the effect of vinegar on insulin area under the curve. Test of overall effect: z = 3.73, p < 0.001.
All together this is decent evidence for the acid as inhibitor of alpha-amylase as mechanism hypothesis
One of the biggest challenges in the vinegar/acid literature is that all of the experiments were done with different meals, protocols, and doses, making it difficult to integrate data from multiple studies. To address this issue and answer some of the open questions about this effect, /u/genetastic, /u/kabong, and I decided to do a series of community self-experiments.
While we each have different motivations and interests, overall, the questions we’re looking to answer are:
Is the effect large enough to matter for practical meals?
What types of meals does vinegar affect?
What is the best protocol to get a large effect without unpleasant side effects?
What’s the underlying mechanism?
Is the effect specific to vinegar or do other acids work?
To answer these questions, we will be conducting experiments using the protocol below.
Methods
Materials
Meals:
white bread (starch)
dried dates (simple sugars)
tortilla with beans, salsa, & avocado (starch, fat, and protein)
Vinegar:
Apple cider or white vinegar
As large a quantity as comfortable, not to exceed 30g
Diluted in as little water as tolerable
Blinding
Vinegar supplementation will not be blinded
However, the protocol was established in advance and adhered to without modification once experiments started.
Procedure
Each participant is using a slightly different procedure
One of the most difficult foods to make low carb is bread. Flour imparts multiple functions to the final product: taste, texture, water absorption, cohesion (via gluten), browning, food for yeast, etc. There are numerous good substitutes for one or the other of these properties, but to get them all, you’d need a complex combination of ingredients.
Recently, there’s been an explosion of commercially available low carb products both on-line and at supermarkets, including a number of low carb breads. Although the net carb counts look good for most of these, I’ve become very suspicious of the blood sugar impact of some of the dietary fibers used (see evidence of blood glucose impact of dietary fibers here & here).
To see if any of these low-carb breads would hold up, I tested them myself. I tested 14 breads from 4 different categories (resistant starch, protein & flour or fiber, and egg & nut), plus regular white bread as a control.
This was the most interesting of my prepared food studies so far. There was a huge variation in taste, texture, and BG impact and some mysteries that I’ll need to unravel (what’s going on with the resistant starches?).
Here’s my overall conclusions:
Lowest BG impact: UnBun UnBread
<10% BG impact of regular white bread; <50% of the next best
Best combination of taste & impact: Carb0naut White & Kiss My Keto Golden Wheat
~25% BG impact of regular white bread
Very different taste & texture, but both really good
There’s a large range in impact from different resistant starches.
No idea what’s going on here, but I’m very curious. Maybe I should source/test different resistant starches and see how their BG impact varies.
Does anyone have any hypotheses? If so, please let me know in the comments.
BG impact is not easy to predict from the primary ingredients or nutrition label due to not knowing the ingredient ratios. Breads with actual flour can have the same impact as ones with indigestible fibers and two breads with the same total and/or net carb count can have wildly different impact.
The only way for me to know the impact of a food is to do a controlled test.
For someone without diabetes, this would probably require eating a large amount, as you’d need to induce an BG rise (since an insulin spike wouldn’t be measurable).
Does anyone know any other good low-carb breads or other low-carb foods I should try?
As always, please let me know if you have any thoughts, suggestions, or anything else you’d like to see me test.
I tested 6 low-carb ice creams from 4 brands (Enlightened, Halo Top, Keto, & Rebel).
All held up to their claims, with relatively low blood sugar impact and taste similar to regular ice cream.
The 6 ice creams had relatively similar blood glucose impact by weight (3-4% of glucose for peak BG/g & 7-10% for iAuC/g) and volume (18-27 mg/dL/cup peak BG & 3,200-4,600 mg/dL/cup iAuC). Of the set, the Keto brand ice cream was ~25% higher than the next worst. Not enough to stop me from eating it, but noticeably worse.
On taste, my favorites were the Rebel Chocolate and Cookies & Cream, but they were all pretty good except for the Keto Triple Chocolate Brownie. Keto brand used erythritol as the only sweetener in the brownie pieces and it crystallized, giving a gritty texture that I really didn’t like. It also didn’t have a strong enough chocolate flavor for my taste.
Does anyone know any other good low-carb ice creams or other low-carb foods I should try?
