Blood Donations & Low Carb Recovery Meals.

Another  experiment in recovering from a blood donation. On my previous two experiments (here and here) I had ingested a lot of sugar (as part of milk chocolate). I had also eaten the usual snacks that they offer at the clinic to help people recover. This time I skipped all that. I wanted to try a low carbohydrate recovery meal and see how I felt. So on the way home from the clinic I picked up a BBQ duck (a whole one) and just ate that along with four bottles of beer (341 ml Unibroue Trois Pistoles – 9% abv ~ works out to about 123 ml of alcohol in total).

The USDA Nutrient Database has the following for half a duck:

Duck, domesticated, meat and skin, cooked, roasted – 1,287 kcal.

So my caloric intake would have been pretty high, somewhere around 2,500 to 2,600 kcal (though I imagine it could easily vary by at a few hundred calories). The database also shows the carbohydrate content of duck to be zero.

Blood glucose in this case hit its maximum at 6.4 mmol/L (or 115.2 mg/dL), but this was after  the beer, not the duck. In the two previous cases, blood glucose had maxed out at 10.0 and 8.3 mmol/L. Note that an hour after eating the duck, the reading was only 5.4 mmol/L, the remaining one point increase can probably be attributed to the carbohydrate/alcohol consumed as part of the beer.

My original plan was to have some vegetables along with the duck, but after finishing the duck I felt so full I didn’t want to do anything further. A better idea would have been to have half a duck along with a plate/bowl of vegetables or something like that.

My subjective feeling that evening was that I felt fine. No worse than after any other blood donation.

The main point I was trying to look at was if typical recovery foods like cookies, fruit juice etc are really necessary. My previous experiments seem to indicate that the body metabolizes sugars better after a blood donation than it otherwise would, but I’m not sure this means that the sugary foods are necessarily a good idea.

One day, of course, is not a recovery. It’s something that happens over an extended period of time (something like two weeks for a blood donation). And the most important indicators of recovery I cannot directly measure myself, like my blood volume and the makeup of my blood.

Here’s a table showing the time and the measurements I took. Note that there was basically no physical activity for the evening, other than walking to and from the clinic half hour each way).

On waking the next day (today) I did feel slightly light in the head. I’m not sure if I should attribute that to what I ate or to what I drank. I made breakfast consisting of: potato, sweet potato, onion, amaranth, quinoa, dried sea vegetables & chicken broth. I felt perfectly back to normal after that.

So what would I conclude from this little experiment? Consumption of sweetened foods is probably not necessary for recovery. It would have been better if I had eaten something more balanced (like having what I had for breakfast along with the duck), but still avoiding sugar altogether worked out quite well.

Blood Glucose & Blood Donations

I had previously done a self-experiment with blood glucose response after completing a blood donation. That time I had consumed 200 grams of milk chocolate and the effect was that donating blood seemed to contribute to a muted blood glucose response.

In this case I wanted to try consuming a much larger quantity of chocolate – 400 grams. The original intent was to consume 500 grams, but I just didn’t feel like eating that much when the time actually came to it. 400 grams was enough to make my stomach feel queasy.

Another thing that I changed from my original intentions was my meal. I had planned to eat a normal meal along with the chocolate, but my stomach was so full I didn’t feel like it. I found this result interesting in itself. Eating all that chocolate had the effect of keeping me from eating anything else, including the meal that would have been healthy and aided in my recovery from the donation process. I think of this as something of a corollary of Gresham’s Law (for those familiar with economics), but in this case bad food drives out good.

That’s part of what happens in these self-experiments, like life they are somewhat messy and impossible to completely pre-arrange.

Note that chocolate is not necessarily junk food – small quantities of dark chocolate have been shown to have some positive health benefits.

The chocolate used was Green and Blacks milk chocolate, 100 gram bars containing:

• 522.5 calories
• 47.5 grams of sugar

Though for some reason on their labeling they give amounts per 40 grams – who eats 40 grams?

The bars were 34% cocoa and sweetened with raw cane sugar, rather than refined sugar.

I also made the measurements more closely together, at 15 minute intervals to more closely track the changes. This is harder on the fingers, but gives a better picture of the physiological changes taking place.

Also notable is how easy it is to consume a large amount of calories in a short period of time. That was 2090 calories consumed during just part of an evening (2.5 hours in this case). That’s pretty close to the caloric requirements for an adult for an entire day.

There was minimal physical activity during the course of the measurements (after I had walked home from the clinic).

So, on to the results. It was striking how initially my readings were very high after having a few snacks at the clinic, though it moderated rather quickly. There were time when my blood glucose seemed to drop fairly quickly. See the data table below.

Note that the snacks, mostly Oreo cookies, contain both refined sugar and refined wheat and perhaps the combination of the two contributed to the result. The pizza would also have contained refined wheat.

Refined wheat + refined sugar vs. chocolate + raw sugar? While I hardly thinks there’s adequate data in this little self-experiment to fully elucidate the comparison, I would prefer the latter. In addition wheat, especially in its refined state, does increase blood glucose substantially.

So here’s the data table with the results.

Note that after sleep the reading was pretty much unchanged, which I found interesting. But then 5.9 is not an especially high reading.

Here’s the graph of the same data.

Note the non-linearity and the ups and downs of the response. The complexity of the body’s feedback mechanisms makes me doubtful of simplistic dietary advice and appreciative of the complexity of the system that we are.

High Milk Chocolate Consumption & Blood Glucose

In some of my previous experiments with the blood glucose meter I’ve tried exercise combined with the consumption of a 200 gram (or two 100 gram) milk chocolate bars. This time I would consume 200 grams twice over and combine it with some vigourous cardiovascular exercise (2 hours and15 minutes of cycling on a hot day, though I’m not sure that heat effects glucose metabolism at all). The exertion level I would rate as the higher end of moderate, definitely working hard.

This time I consumed 200 grams of milk chocolate (containing 80 grams of sugar) before beginning the exercise session. Then I consumed another 200 grams of the same chocolate after completing the exercise session. Based on my previous experiences, combining exercise with consumption of 200 grams of milk chocolate seriously blunted the blood glucose response when I consumed the chocolate either before or after a similar exercise session. I wanted to see if doubling the chocolate consumption would still result in a blunted blood glucose response, especially after consuming the second 200 grams.

Here’s a table showing the results.

The blood glucose response did seem moderated by the exercise. There two peaks in blood glucose after consuming the chocolate were:

7.6 – after the first 200 grams, while exercising

6.8 – after the second 200 grams, after finishing exercising

Interestingly the highest reading I got for the day was 8.8 later in the evening after eating some soup that had rice and oats in it. Perhaps that reading was a glitch, but I took a second reading and got 7.7, lower but still higher than any of the earlier readings.

And here’s a graph of the results showing the peaks in blood glucose readings after each chocolate consumption and the final peak after having chicken soup with some whole grains.

Here’s a table comparing the peaks in blood glucose after chocolate consumption this time to the prior experiments.

While conditions are always different, this time the were pretty much in line with the prior occasions despite 400 grams of milk chocolate being consumed instead of 200. The exercise protocols were pretty similar across the experiments, cycling a similar route each time (though the actual time varied).

Cashews & Blood Sugar

I read a piece about research into cashews and blood sugar at 1 great day, based on  a piece of research originally published in Molecular Nutrition and Food Research (published online July 5, 2010) entitled “Hydro-ethanolic extract of cashew tree (Anacardium occidentale) nut and its principal compound, anacardic acid, stimulate glucose uptake in C2C12 muscle cells”. The entire article is not available online (not for free at least) but the abstract can be viewed.

The upshot seems to be that an extract of cashew seed seems to have been effective in stimulating the uptake of glucose by muscle cells in rat livers. Nothing was tested on humans here, even though cashew seed extract does not sound especially hazardous. Hydroethanolic just means water and alcohol and appears to be a common means of preparing extracts of plant products.

It’s interesting to note that the study was partially funded by Institute of Nutraceuticals and Functional Foods, so the production of a commercially available extract would seem to be a possible eventuality.

Since we don’t have access to cashew seed extract (in any form, as far as I know) it’s probably a good idea to just eat some whole cashews now and then. Extracts potentially have a few shortcomings compared to the foods they are extracted from:

1. don’t taste as good
2. cost more
3. lack the other micro nutrients, fiber & fatty acids present in the original food

To get an idea of what might be missing I checked the USDA nutrient database for the nutritional content of 100 grams of raw cashews (which is not really a very large serving). Here’s the vitamin and mineral content.

A fairly wide array of nutrients. In addition there’s some fiber and a number of (primarily mono-unsaturated) fatty acids.

How much cashew you’d have to eat to get the effective dose mentioned in the article (“Significant synergistic effect on glucose uptake with insulin was noticed at 100 g/mL CSE”) I really don’t know and I’m not sure how you’d go about calculating that and translating it into an effective dose for a human.

So it might be a good idea to just eat some cashews now and then, since they’re probably pretty good for you anyways.

Blood Donations & Blood Glucose

On previous occasions when I had donated blood I had noticed that if I consumed a lot of sugary foods afterwards it didn’t have the same effect as it usually did. Normally I would have difficulty getting to sleep, but not after donating blood. So for my most recent blood donation I checked by blood sugar before and then several times after my donation to see if the effect could be measured.

It turns out there really is a difference. After eating a few snacks at the clinic (some oreos and orange juice) I walked home (about 20 minutes). I ate two 100 gram bars of milk chocolate (containing 95 grams of sugar). On previous occasions eating 200 grams of milk chocolate had resulted in my blood glucose spiking to 10.3 mmol/L. On this occasion however, the rise in blood glucose was far lower, only going to 8.3 mmol/L, even though the actual sugar consumed was higher this time due to a difference in the chocolate (95 grams vs 80 grams of sugar).

Here’s the table showing the data.

And a table showing the maximum blood glucose readings with eating 200 grams of milk chocolate under different conditions.

It’s a pretty significant difference, specially considering that more sugar was consumed this time. The data confirm my earlier subjective evaluation. Here’s a chart showing the initial pre-donation reading and then the changes afterwards.

Blood glucose & cardiovascular exercise

Previously I had tried eating milk chocolate followed by no exercise and doing the same but followed by cardiovascular exercise. There was a marked difference in the blood glucose response. This time I tried cardiovascular exercise (moderate intensity cycling) and consuming the milk chocolate afterwards, as well as a bowl of cherries.

As in the last case I had 200 grams of milk chocolate, in this case Green & Blacks Almond Milk Chocolate (34% cocoa) which contained a total of 80 grams of sugar (same as the Cote d’Or chocolate in the previous test).

Here’s a table of the data:

And here’s a breakdown of the carbohydrate composition of cherries from the USDA nutrient database:

Here’s a summary of the maximum blood glucose readings under the three different protocols:

And finally here’s a graph of the blood glucose readings through the day showing the increased readings after eating milk chocolate and a bunch of cherries:

Strawberries, Cream & Other Things.

This time out I wanted to see the effect of fruit consumption on blood glucose when mixed with other foods (which would be typical of most people’s eating patterns). The strawberries is overwhelmingly carbohydrate. According to the USDA nutrient database 100 grams of strawberries is composed of:

• fat           0.30 grams
• protein   0.67 grams
• carb        7.68 grams

And the carbohydrate portion is primarily composed of the following sugars:

• sucrose 0.47 grams
• glucose 1.99 grams
• fructose 2.44 grams

The other elements of the meal were very fat and protein centered (crème fraiche, eggs & sheep’s milk). Here’s a table with the results:

Note that initial reading was taken after not having eaten for something like 16 hours. I had no breakfast that day, so the previous evening’s supper was the last thing i had to eat. Probably as a result, even after 4 and a half hours my blood glucose hadn’t come all the way back down to the starting point. Here’s the chart:

The change is actually pretty moderate, despite it being an entire pound (454 grams) of strawberries. It seems to go up and down a bit and I’m not sure if that’s measurement error of some sort or just caused by the body’s metabolic variation and things don’t just go straight up or straight down sometimes. Whatever the cause, it appeared the increase in blood glucose was neither very dramatic nor very long lived.

Coconut Milk With & Without Starchy Tubers

A test of how some different foods interact with each other and specifically with coconut milk. Both meals were coconut milk, tuna and vegetables. The first included sweet potato and red potato as part of the vegetables, the second did not. Here’s a table of the blood glucose response of the first meal.

And here’s the chart showing the change in blood glucose levels over the course of that evening.

Here’s the table with the data for the second meal (a different evening) for a meal that is overall very similar, but which excludes the potato and sweet potato.

And the graph illustrating the pretty much non-existent change in blood glucose.

Both graphs are scaled the same so they are readily comparable. The flatness of the latter is remarkable.

Here’s a chart comparing the two. Note that they have different initial blood glucose readings, so the first dataset (tubers) starts off a bit higher.

Note that since the times were different for the two datasets, I used zero as the starting point in this graph.

If we look at the percentage changes in each scenario (to avoid the difference in initial readings) it looks like this:

Even though the meal including the potatoes and sweet potatoes had a blood glucose response that  was not as pronounced as with other foods I’ve tried, it’s still a quite significantly greater response than just having other vegetables.

Comparing blood glucose responses with and without exercise

Two earlier experiments with the same 200 gram Core d’Or hazelnut and milk chocolate bars, yielded very different results under sedentary and exercise conditions. Here are two different graphical representations of the data. Blood glucose is measured in mmol/L, but it’s the relative change I’m looking at, so using mg/dL would not make any difference. First using the actual values for each measurement, a table of the data and a graph.

And the graph. Note that the starting points are different on the two datasets due to the initial reading being different.

To get around the starting points being different, here is the same data expressed as a percentage change from the initial reading.

And the graph based on the same data.

From either graph it’s pretty obvious that continuous exercise makes a major difference in the bodies metabolization of sugar. The area under the curve in the exercise condition is considerably smaller and the rate of increase is considerably slower.

Cardiovascular exercise & blood glucose

How much of the spike in blood glucose caused by ingesting sugar is offset by physical activity? I tried to find out by eating a 200 gram bar of milk chocolate (relatively sweet) and then going out and doing what I would call moderate intensity cycling (I don’t have a cycling computer so I don’t have the data on distance covered or average speed).

This is the same chocolate bar I had eaten in a previous test, which had resulted in a peak blood glucose reading of 10.3 mmol/L  (or 185 mg/dL). That test involved fairly minimal physical activity. This time it peaked at 6.3 mmol/L (or 113 mg/dL), a pretty large difference.  Total time spent cycling was 3 hours. Here’s a table of the data.

After 3.5 hours blood glucose was back to where it had started. Here’s a graph showing the gradual rise and fall.

It’s actually a pretty dramatic difference, 6.3 versus 10.3. Physical activity levels really do affect the rate at which our bodies metabolize what we eat. In this case a large dose of sweet chocolate elicits a blood glucose response that would otherwise be associated with a foodstuff containing little sugar or starch.