Tag Archive for: bioavailability

Bioavailability Ends with Bioactivity

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Here’s where we stand: we’ve digested a nutrient and it’s been absorbed into the bloodstream. How is it going to be used? How do we get the benefit of vitamin C, magnesium, alpha-carotene, or caffeine? Let’s take a look.

Many target cells have receptors that are specific to a nutrient, like a wrench that fits only one size of bolt. For example, when blood sugar rises after pasta is digested and absorbed, insulin is released from the pancreas. Insulin will attach to a specific insulin receptor on the cell membrane, and that will allow a glucose molecule to enter the cell to be used. Cells also have receptors for vitamin C to be absorbed into cells.

That’s fairly straightforward. The next step would be actually performing a function once the nutrient enters the target tissue. Let’s look at caffeine for example. There’s a genetic factor; one version of a gene can process caffeine quickly while a mutation of that gene processes it slowly. I can drink coffee and immediately go to sleep. Others may process it slowly and may not be able to sleep in the evening after a cup of coffee for lunch. Same nutrient, different effects on different people.

In addition, there are numerous enzymes that help make chemicals such as hormones or structures such as cartilage. If enough of an enzyme isn’t being manufactured or it’s blocked from being utilized, that can have an impact on how well a nutrient works. An example would be insulin; if cells are not producing enough receptors, or the receptors are resistant to insulin, blood sugar would rise. That leads to overall insulin resistance, one aspect of being prediabetic.

Another example would be the manufacture of glucosamine. The process requires fructose-6-phosphate and the amino acid glutamine; the first is a result of the breakdown of sugar while the later is the most prevalent protein-building amino acid in the body. The manufacture of glucosamine also requires an enzyme. If a person doesn’t make enough of that enzyme, that affects the production of glucosamine which then impacts the production of other forms of connective tissue such as cartilage, ligaments, and bone.

The Bottom Line

Every day there are new nutrition products introduced that are supposed to be better for you because more nutrients are available, but nutrition just doesn’t work that way. As I’ve tried to show you this week, the problem is that it isn’t quite as simple as what you see in Internet ads. Nutrients have to be digested, absorbed, and used by the body, and things can go wrong at any step along the way. Each individual’s body is unique and comes with its own idiosyncrasies and difficulties, and that’s what makes nutrition so complicated.

Maybe you’re thinking, “What’s the point if so much can go wrong?” What you have to remember is that most of the time everything works just as it should; not everything related to bioavailability goes wrong in every person. It’s also a matter of degree—maybe absorption will be cut by 50% or activity reduced 10%. I want you to understand why some nutrients won’t work as expected for a particular person, and why claims of better bioavailability aren’t a guarantee.

Yet we’re still here, aren’t we? We’re here because our ancestors survived. To steal a line from “Jurassic Park”: Nature finds a way.

What are you prepared to do today?

Dr. Chet

 

Reference: http://bit.ly/2raDviy

 

Bioavailability Continues with Absorption

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On Tuesday I talked about some of the processing required to get nutrients ready for absorption. The next phase of bioavailability is the absorption of the nutrient from the gut into the bloodstream. Let’s look at what’s involved.

The absorption process occurs via the intestinal epithelial cells and they vary in size and function in the small and large intestine. Some nutrients such as lipids may use a passive process to be absorbed. Sugars, amino acids, and others will use an active process involving transporter enzymes as well as using energy to be absorbed. Vitamin B12 absorption is much more complicated; it requires something called intrinsic factor and then is passed to another protein carrier for absorption.

Here’s where absorption can go wrong. Maybe you don’t produce enough of a transporter enzyme for one or more amino acids. Perhaps you have a condition such as irritable bowel syndrome, and some of the areas where absorption occurs are missing. There are more scenarios related to absorption, but they can all lead to a lack of bioavailability. Then there’s the fact that all our bodies are the tiniest bit different. Because most absorption studies are done with simulations of the digestive system cells, product claims of greater bioavailability can easily differ from what actually goes on in your digestive system.

Let’s say that you have digested and absorbed a nutrient. Does that mean your body will actually be able to utilize the nutrient? That’s the topic of Saturday’s Memo.

What are you prepared to do today?

Dr. Chet

 

Reference: http://bit.ly/2raDviy

 

Bioavailability Begins with Digestion

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Last Saturday’s Memo introduced a new concept: a systems approach to nutrition. One term that gets bounced around a lot related to dietary supplements or different types of food is bioavailability. Claims are made that “this form of our supplement is 10 times more bioavailable than that form.” It sounds so simple, right? It’s not—we’ll spend this week looking at all that’s involved in bioavailability. It begins with the entire digestive system.

Digestion is the process of breaking down a food or nutrient for absorption. There may be plenty of a nutrient consumed, but it has to be broken down into a form that can be absorbed. That begins in the mouth by chewing, and then the action really heats up in the stomach; acids are released to break the food into smaller molecules, if required. After leaving the stomach, the digestive enzymes begin to work on the food to continue the process. If it’s a nutrient from a supplement, it may be absorbed as it is or it may need to be modified biochemically. As the nutrient continues through the small and the large intestine, it may require a modification by bacteria before it can be absorbed.

There are many points in the process that can affect absorption. Does a person’s stomach release enough acid? Does the pancreas make enough digestive enzymes? Is there enough food that provides chelating agents for minerals? Is the microbiome healthy enough to continue the breakdown of the nutrient? You can see how the system can be affected in numerous places. But we’re not done yet. On Thursday, we’ll talk about absorption.

What are you prepared to do today?

Dr. Chet

 

Reference: http://bit.ly/2raDviy

 

Curcumin and Pepper

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I’m just back from Peoria, and there’s nothing like spending a couple of days with health-conscious people to yield some very interesting questions. This week, I’m going to examine one question in detail: is turmeric absorbed as effectively without pepper in the blend? A phytonutrient found in turmeric called curcumin is being extensively studied for its anti-inflammatory and antioxidant effects. But pepper? I checked into it and here’s what I found.

In a study done in 1998, researchers examined the absorption of curcumin with and without piperine, the phytonutrient that provides the pungent smell . . .

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The Best Source of Calcium

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Let’s go back to where we began. Is any form of calcium, whether from foods, supplements, or some new-fangled source, any better absorbed than another?

No—not enough that it would make a real difference, anyway. There are two primary forms of calcium available that have lead to this absorption controversy, so let’s take a look at them. In supplement form, calcium carbonate has the most calcium per mg at 40% while calcium citrate has about 20%. That means that fewer milligrams of calcium carbonate are needed to get the amount a person needs to take.

The . . .

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Calcium Absorption

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As you might predict, I get a lot of questions about dietary supplements. People read about some just-discovered source of a nutrient and the claims that it’s better absorbed, and they wonder: is this better than the supplement I’m taking? Such is the case with calcium. A company has claimed that their form of calcium from algae is better absorbed.

Let’s start off with a general overview of calcium absorption. Calcium is poorly absorbed regardless of the source—doesn’t matter whether it’s dairy products, fish with soft bones such as sardines, or in supplements . . .

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