Tag Archive for: rice

Unusual Question: Resistant Starch and Food Prep

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Resistant starch (RS) has qualities that are somewhat unique. As it’s being touted today, RS will help reduce the glycemic response to some carbohydrate-based foods. The issue is that when and how an RS containing food is prepared and consumed seems to be important. Let’s take a look.

Food Preparation Methods

The most natural forms of resistant starch to eat, regardless of preparation, are beans, seeds, nuts, and legumes. The food preparation doesn’t seem to impact the RS in any way, so these are the best ways to get RS.

Eating bananas and plantains when they’re green provides a high amount of RS. The more they’re allowed to ripen, the higher the sugar content and the less RS.

Raw potatoes also seem to have a high amount of RS. Because most people don’t eat raw potatoes, the type of preparation impacts RS levels. The longer the potatoes are cooked, the more the starch is changed into sugars or starches that don’t contain as much RS. In a review study of potatoes, the cooking method that contains the most RS was baked, followed by deep-fried, and finally boiled. The problem with deep-fried is the additional fat.

Does Cooling Increase RS?

We rarely hear about nutrients being increased by food prep, but RS may be the exception. A lot of the recent focus on RS surrounds the possibility of increasing RS by cooking and then cooling the foods before eating. The RS that degenerates during cooking is partially restored in cooling, particularly in rice and pasta.

However, in a study that examined the difference between rice that was eaten immediately, kept at room temperature and eaten eight hours later, and cooled for 24 hours and then eaten, the amount of fiber increased by 0.64 grams, 1.3 grams, and 1.65 grams per 100 grams serving. Stated slightly differently, in a half-cup portion, there was an increase of one gram of fiber per serving. While it’s true, it’s not meaningful in the real world and probably not worth the additional effort.

RS and Type 2 Diabetes

Another benefit of RS is to reduce the amount of sugar that enters the blood stream. In the rice study, the cooked and cooled rice was fed to 15 healthy volunteers. Their glycemic response was reduced. While I think that’s great, there’s no indication that this will happen in T2D. On top of that, think about the additional steps required to achieve that. I think there’s a better way.

The Bottom Line

Resistant starch is legit; it acts as a prebiotic and reduces the glycemic response, but I don’t think we need to go out of our way to get more of it. Increasing our intake of beans, seeds, legumes, and nuts will increase our RS the most without jumping through hoops. If you like green bananas, eat them. Cook your pasta al dente and that maintains some of the RS in pasta. If you like to cook extra rice and pasta to use in later meals, now you know there’s a nutritional benefit. You don’t need to do anything else but eat the foods that naturally contain RS. Simply put, just eat better.

Next week is all your questions, so send them in if you haven’t already.

What are you prepared to do today?

        Dr. Chet

References:
1. Nutrients. 2018 Nov 14;10(11). pii: E1764. doi: 10.3390/nu10111764.
2. Asia Pac J Clin Nutr 2015;24(4):620-625.

Rising CO2 and Nutrition: The Bottom Line

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All of nature is a delicate balance; when any component changes, there will be some sort of effect—maybe good, maybe not. The mineral nutrient and trace element content composition of a plant, technically called the ionome, reflects a balance between carbon, obtained through CO2 in the air, and the remaining nutrients, obtained from the soil. If the CO2 increases in a disproportionate way to the nutrients available from the soil, it could create an ionomic imbalance. In other words, the balance of nutrients is disrupted. This imbalance in CO2 and soil nutrients could affect the nutrient content of the plant including the protein and micronutrients.

That’s exactly what scientists found in their research. Remember, they used a CO2 level in the FACE-field testing to mimic CO2 levels at the end of the 21st century. Most species of rice declined in protein, iron, and zinc, but that was expected based on prior research. But there were also consistent reductions in vitamins B1, B2, B5, and B9. On the upside, they did find an increase in vitamin E in some varieties of the rice.

Here’s the concern: rice is a staple for two billion people. In fact, it’s their primary source of nutrients because food is not plentiful in many of those countries. A 10% decline in protein could have a major impact on the growth and development of the people dependent on rice for their primary food source. The same is true for any of the other nutrients; they’re critical for the immune system and many other biochemical functions.

The Bottom Line—For Now

While this research is real, it’s most definitely not complete yet. The CO2 projections for the turn of the century may not be accurate; they could be lower or they could be even higher. What if they were higher? Let’s take it one step farther and consider the food supply in the U.S. and Canada right now. What if the current CO2 levels are having an impact on our food supply now, not just on rice, but in all the food that’s grown? What if our food is becoming less nutritious?

This raises two points. If there were ever a reason to complement your diet with dietary supplements, this would be it.

Take it a step further. I get more queries on what people can and cannot eat because they have issues with specific foods such as wheat. What if it’s not the gluten in wheat that’s the problem? What if it’s the changes in nutrient content that upsets the balance of amino acids? Or the B vitamins? That imbalance may be the actual culprit. Only more research will tell.

This one is far from over. I’ll keep watching to keep you informed.

What are you prepared to do today?

Dr. Chet

 

Reference: Science Advances: DOI: 10.1126/sciadv.aaq1012.

 

How Researchers Determined the Effect of CO2 on Nutrition

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An international group of researchers wanted to know how higher CO2 levels would impact the nutrient content of a staple in the diet of over two billion people: rice. If the nutrient levels change substantially, that could have an impact on the nutritional status of many people who might already be undernourished.

Over several years the researchers grew 18 strains of rice that are raised throughout the world. They used an interesting technique called FACE, which stands for free-air CO2 enrichment. The technique uses tubing to emit CO2 near the plants. The amount emitted is dependent on the CO2 levels on the plot of land and controlled by sensors. That allows them to keep the CO2 levels constant just as they would be when grown in fields while the plants grow in a natural outdoors setting.

The researchers used the CO2 levels that are estimated to occur by the end of this century. True, none of us will likely be alive by then, but most of us know people who will be. The knowledge gives agricultural scientists time to develop plants that can grow with adequate nutrient content in those CO2 levels. CO2 may not increase as expected, but future generations can be prepared if they do.

What did they find? I’ll let you know on Saturday.

What are you prepared to do today?

Dr. Chet

 

Reference: Science Advances: DOI: 10.1126/sciadv.aaq1012.