Tag Archive for: nutrition

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

 

I’m Recommending a Broccoli Bath

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This week’s final question is whether cooking destroys the nutrients in vegetables. If it does, is there any method better than others for preserving the nutrient content? Let’s take a look.

Researchers examined three cooking methods with several vegetables including broccoli. The methods were boiling, sous-vide cooking, and water immersion cooking at temperatures below 212 degrees F, water’s boiling point. The objective was to see the effect on phytonutrient content of each vegetable.

Your first question is probably this: what is sous-vide cooking? I didn’t know even after all the cooking shows I’ve watched. Sous-vide is French for under vacuum. The general idea is that the food is placed in a plastic bag, air is removed by vacuum, and the food is cooked in a water bath at relatively low temperatures (130–150 degrees) for a longer period of time. A low-tech alternative is to place the vegetables in a plastic bag, immerse the bag in water until the air escapes, and submerge it in a low-temp water bath during cooking.

Which worked best? Sous-vide cooking preserved chlorophyll, carotenoids, phenolic content, and antioxidant activity to a greater extent than boiling for all of the vegetables tested. Second was cooking in hot water below the boiling point (150–160 degrees). The lower temperature improved the qualities of the samples cooked in water including the color of the vegetables. Boiling resulted in the greatest loss of the most nutrients.

If you usually microwave broccoli as we do, that’s a good method as well. It compares most closely with cooking vegetables at a low temperature as long as you cook it for as short a time and with as little water as possible. A microwave steamer is your best bet.

The important point is that cooking, including boiling, does not remove all beneficial nutrients. Probiotics will be sacrificed but some vitamins, minerals, and phytonutrients will still be in the cooked broccoli.

 

The Bottom Line

The bottom line on broccoli, as well as almost all vegetables, is that processing, whether by cutting, freezing, or cooking, will not remove the nutrients from the vegetables. The most important thing you can do is to eat them. The benefits to your body will be there.

What are you prepared to do today?

Dr. Chet

 

Reference: Food Chem. 2017 Feb 15;217:209-216. doi: 10.1016/j.foodchem.2016.08.067.

 

Would You Eat a Broccoli Popsicle?

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Uh-h-h-h, no. I don’t think I could convince anyone to eat a popsicle made of broccoli. But the question is: does freezing affect the nutrient content of broccoli? If it does, would it increase the nutrients like cutting it up does or lower the nutrient content compared to fresh?

That’s what researchers attempted to find out. They examined several varieties of broccoli that were frozen using an industrial freezing process, a method that’s much faster and colder than freezing vegetables at home. They found that some phytonutrients such as glucosinolates increased while total phenols remained constant in most broccoli cultivars. When they looked at carotenoids, there were higher levels in the industrial frozen broccoli when compared to fresh broccoli.

Why would freezing increase some of the phytonutrients? It may be that cells walls are damaged thus releasing the protective qualities of the phytonutrients. Whatever the reason, you can count on frozen broccoli to give you the phytonutrients we need from this vegetable.

In my research, I found different types of broccoli named Iron Man and Avenger. You want to have your kids eat more broccoli? Plant a garden next year with those catchily named broccoli cultivars and watch it disappear. No broccoli popsicle needed!

Saturday, what does cooking do to broccoli?

What are you prepared to do today?

Dr. Chet

 

Reference: Int J Food Sci Nutr. 2015 May;66(3):282-8. doi: 10.3109/09637486.2015.1007451.

 

Broccoli: Cut It Up

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In preparing my 2018 nutrition seminar, I came across a paper on why we need to supplement our diet with a multivitamin-multimineral (I’ll be giving an overview of that paper in the next Insider Conference Call next week), and it raised a question. Quality supplements have precise amounts of specific nutrients. But what affects the nutrient content of the foods we eat, specifically vegetables? Processing? Freezing? Cooking? I picked one vegetable, broccoli, to see what I could find.

Let’s start with processing. Researchers decided to see how cutting broccoli would affect phytonutrient content. Phytonutrients are chemicals in plants that help protect the plant; when we eat the plant, they seem to help us as well. The scientists cut broccoli florets several ways: in half, into quarters, chopped it up, and kept a floret whole with just a single cut from the stem. They immediately analyzed the phytonutrient content, then stored them, and analyzed them again 24 hours later. No matter the method of cutting the broccoli, the phytonutrient content increased—yes, it increased. However, cutting the floret into quarters seemed to increase the cancer-fighting isothiocyanates and sulforaphanes the most, immediately and after storing for 24 hours.

Why did the phytonutrients increase? Because they’re designed to protect the plant from harm. Cutting means damage, and the plant is protecting itself.

What can it mean to us? Cutting up our vegetables may increase the phytonutrients that are available to us after we eat them; better yet, cut them up early and store them to give them time to marshal their forces.

Would the same thing happen with chewing? Not exactly as the enzymes in our mouth and digestive system may impede the process.

When you see the cut-up vegetables that dominate salad bars and party trays, think about eating those first before you start eating anything else. Thursday, it’s on to the effects of freezing on nutrient content.

What are you prepared to do today?

Dr. Chet

 

Reference: Molecules. 2017 Apr 15;22(4). pii: E636. doi: 10.3390/molecules22040636.

 

Classic: Type III Error

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You know that eating fruits and vegetables is good for you, right? I tell you that all the time because that’s what the research indicates. But according to an editorial piece in the Journal of the American Medical Association (JAMA), maybe we’ve been wrong all this time (1)—at least as it relates to reducing our risk of cancer. Here’s a recap of the editorial and my take on it.


The Editorial

Mike Mitka is a well respected senior writer for JAMA; he’s published numerous articles that are well researched and contain interviews with the authors and other experts. In a 2010 JAMA article, he writes that an article from the European Prospective Investigation into Cancer and Nutrition (EPIC) clearly demonstrates that high intakes of fruits and vegetables do not reduce the risk of cancer, at least not very much.

Based on the study published in the Journal of the National Cancer Institute, increasing fruit and vegetable intake by six ounces per day reduced the risk of cancer only 3% (2). A couple of well-known researchers supported the notion that research does not support plant intake reducing the risk of cancer, including the director of nutrition for the American Cancer Society.

The problem is that it’s just not true, at least not in that study. The way it’s written, the study suggests that when subjects increased their intake of vegetables and fruits by six ounces, the reduction of cancer risk was a paltry 3%. This was an observational study, not an interventional study. No one kept track of who increased or decreased their plant material intake, and there’s no way to know that from the data collected.

The way I read the article, the EPIC study is central to this new belief about plant consumption not being related to decreased cancer risk. The first articles from the study were published in 2003, and that’s when scientists suggest the evidence grew weaker supporting reducing cancer by plant consumption.

I’ve written about EPIC before; it’s one of the largest observational studies ever conducted with over 520,000 subjects from 23 different centers in 10 European countries. While I suggested that there was strength in numbers when you want to try to tease out subtle effects, I mentioned that the researchers gathered nutritional information at the beginning of the study with a Food Frequency Questionnaire; subjects were asked as many as 256 questions about what they had eaten in the past year. There are two problems with that when you’re looking at the rate of cancer.

First, you have to assume that this one-time questionnaire on diet applies to the patterns of the way the subjects ate and will continue to eat. By the validation studies that were done for the EPIC study itself, that certainly was not true (3). Correlations between what people ate one year apart were as low as 36% in a sub-sample of the subjects. Researchers chose to adjust levels statistically, but that just isn’t the same as actually collecting the data. But when you’re dealing with a half million subjects, you just can’t collect dietary histories on every subject.

Second, the assumption is that the levels that the subjects ate were actually adequate to reduce the rate of cancer. In the study, the average fruits and vegetable intake for men was 17 ounces per day and about 19 ounces per day for women (4). Using an example from the editorial, a medium apple is 10 ounces and a serving of broccoli is about 3.5 ounces. That’s just two servings and that’s close to what the subjects actually ate.

The fact is that most subjects in the study did not eat very many vegetables and fruits and it got worse the further north the country was located. That should have been the overwhelming conclusion of the study to begin with before any other analysis was conducted.


My Take

Trying to explain statistics is not my strong suit, but I adapted this from a blog by Satoshi Kanazawa, an evolutionary psychologist in London and a contributor to Psychology Today (5).

There are two types of errors in statistics. There’s the error of a false positive: you think that the data reflect your hypothesis when it doesn’t. Then there’s the error of false negative: you think the results do not support your hypothesis when it does. Statisticians call the former type of errors “type I errors” and the latter type of errors “type II errors.”

My feeling is that Mitka and researchers who are using the EPIC study to make suggestions about the relationship between plant intake and cancer risk are committing a “type III error.” What’s that? An unwavering belief in statistics: you don’t look at anything but the numbers, and that rules what you believe. Maybe a better way of describing a type III error is hubris, an overbearing pride in statistics. These researchers are very smart people. Did no one consider that the way the data were collected didn’t make sense when tracking diet’s effect on cancer risk? That’s hard to believe unless pride gets in your way.

But when you get right down to it, if you eat an apple and some broccoli on a typical day and someone told you that adding a banana or a tomato would reduce your risk of cancer by 3%, doesn’t it seem like a great idea to add that banana or tomato? Imagine what you could do if you actually ate the recommended eight to ten servings!


The Bottom Line

This will not be the last time I write about EPIC because there are over 500 articles published to date. I still think that eating more vegetables and fruit reduces the risk of all disease including cancer based on the thousands of other studies that say that it does. It seems like the larger the study, the less beneficial effects anything seems to have whether it’s diet, exercise, or supplementation. Maybe someone should start considering whether the effects are being washed out by regressing to the mean. But that’s a message for another day. Time for some berries!

What are you prepared to do today?

Dr. Chet

 

References:
1. JAMA. 2010; 303 (21): 2127-9.
2. J Natl Cancer Inst. 2010 Apr 21;102(8):529-37.
3. International Journal of Epidemiology 1997; 26 (Suppl. 1): S26–S36.
4. Public Health Nutrition: 5(6B), 1179–1196.
5. www.psychologytoday.com/blog/bloggers/satoshi-kanazawa

 

Nutrition Can’t Fix Everything: Your Genetics

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In this final post on why nutrition can’t fix everything, let’s take a look at genetics. All things being equal, genetics—specifically minor mutations in our genes—is probably the biggest reason why nutrition can’t fix everything. Here are a few examples to explain why it can’t.

For someone with celiac disease, a genetic test can confirm the diagnosis. Once confirmed, the person should no longer eat any foods with gluten to avoid digestive issues. No other nutrient, enzyme, or probiotic can repair the gene. Nutrition can’t fix it.

In last Saturday’s message, I . . .

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Nutrition Can’t Fix Everything: Your Microbiome

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In this post, I’ll cover another reason that nutrition can’t fix everything: our microbiome, the bacteria, fungi, viruses, and other microorganisms that live on and in our bodies. From birth, our microbiome is the result of contact with our mothers and others, our environment, and the foods we eat and don’t eat. It’s also the result of the antibiotics we’ve taken when we’re sick as well as those that have been in the foods we’ve eaten.

Our microbiome works best when it’s in balance; the problem is that doesn’t happen in . . .

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Nutrition Can’t Fix Everything: Baggage

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Happy New Year! I hope you’re ready to make your health a priority in 2017. Let’s begin the New Year right with a statement I discussed in my monthly conference call. I received an email in which someone was convinced that there was a nutritional solution to a health issue that she was having. I thought about that for a couple of months—not her condition but the question in general.

Nutrition cannot fix everything, whether a change in diet or a supplement. I’m going to give you three reasons this week as to why.

Let’s . . .

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