Prebiotics work not only in the gut, but also have been proposed to play an important role in a large range of health benefits from reducing disease risk to possibly curing disease. (As I write this, the words from Stephen Sondheim's "Pirelli's Miracle Elixir" from Sweeney Todd are stuck in my brain.) The claims are long but I will try to put them in large categories.
Prebiotics work on a limited number of gut microorganisms. As a result of prebiotics' ability to change the growth OR the activities of certain gut organisms prebiotics are claimed to do the following:
1. Improve the gut composition which leads to improved gut functions including stool regularity.
2. Improve immune function
3. Decrease the risk of colon cancer
4. Improve mineral absorption
5. Decrease GI infections
6. Decreases obesity, metabolic syndrome and its related problems
This then leads to the myriad of health benefits that are all over the Internet.
I will again look at good studies in humans, explain results that have only occurred in labs, and what is theory. The majority of studies have been done using food ingredients which belong to two groups - inulin-type fructans (ITF) and galacto-oligosaccharides (GOS). These have been shown to stimulate lactobacilli and bifidobacteria, which are good bacteria. To be classified as a prebiotic, it has to be resistant to hydrolysis and GI absorption before the colon, must be fermented by the intestinal micro flora and stimulate the intestinal bacteria associated with health of humans.
IMPROVE GUT COMPOSITION
In a normal gut, things go through the small intestine more quickly compared to the large intestine so there are more bacteria in the large intestine as well as more undigested food. This is where the prebiotics work. The food that we are unable to digest (fiber, complex sugars and proteins) as well lining substances of the gut are fermented by the bacteria and used as their energy source with metabolites left over. These products influence the gut motility.
In only 2 studies were they able to show a positive effect in gut motility with patients that had Irritable Bowel Syndrome. Those patients took 5-7 grams/day of a prebiotic to have an improvement in symptoms. All the other well designed studies showed less good outcomes and they used lower or higher doses.
IMPROVE IMMUNE FUNCTION
There are some very good theories that prebiotics ought to influence the immune system because the gut, through the gut-associated lymphoid tissue (GALT) is significantly involved in both preventing and modifying disease. The problem is that the human GI system is not easily accessible for study. So far the best studies are done in the lab and none have been confirmed with well-designed human studies.
A number of clinical studies are being done in Inflammatory Bowel Disease (IBD). The problems with the studies are many but the ingredients are safe and some of the early results deserve further investigation.
Prebiotics have been added to infant formula to make it more like breast milk, which does improve babies' immunity. The stools do show an increase of bifidobacteria, but whether that translates to improved human health has yet to be proved.
COLON CANCER
The bacteria in your gut manufacture chemicals and some of them can be carcinogens and toxic. Good bacteria produce a low number of carcinogens and bad bacteria produce a large number of toxins by comparison. In theory, if you have good bacteria, you should have less production of toxic waste products in your gut and less risk of cancer. In animals there is a a reduction in colon cancer and in humans, there seems to be a decrease in bio markers in patients at risk for colon cancer who were given symbionics (pre and probiotics.) It has not been proven that there is a decrease risk of cancer in humans, but again, this is a difficult study to do.
MINERAL ABSORPTION
A number of well-designed studies have shown an increase absorption of calcium in prepubertal girls and boys and late post menopausal women. In healthy infants, prebiotics increased iron and magnesium absorption; and in early menopause there is increased copper absorption. In the studies that showed the best mineral absorption, it appears not only is the dose important, but that also using a combination of prebiotics made the mineral absorption more effective.
Whether or not increased absorption leads to improved health has only been proved in lab animals. Although it seems reasonable, the bone metabolism of post-menopausal women is more complex and much of the previous dogma that we have taught women to do (like take high dose calcium) is now being questioned. So far no decrease in the risk of osteoporosis has been shown with prebiotics.
DECREASED GI INFECTIONS
The studies show some effect in rats, and some moderate success in prevention of traveler's diarrhea in humans, but otherwise this has not been as successful as probiotics.
OBESITY AND METABOLIC DISORDERS
Most of the studies on this subject have been done in animals. They have shown a decrease in fat mass, but not a decrease in weight. Also, there is better glucose, lipid, triglyceride, and cholesterol metabolism in the rats. The few human studies available seem to show that prebiotics work by producing a peptide that regulates appetite. But so far whether or not this will actually work in humans has not be shown. What the importance of the actual microbes in the gut are in humans has not been explored because the studies have all sorts of difficulties in trying to devise double blind studies with good placebos
AVAILABILITY OF FOOD
Many regular foods contain prebiotics. These include leeks, onions, Jerusalem artichoke, garlic, asparagus and bananas, to name a few. The quantity of what you have to eat of them to achieve a prebiotic effect differs with the food. Also, the caloric quantity of the food changes which will modify the health benefits of the prebiotic.
SIDE EFFECTS of PREBIOTICS
Prebiotics are fermented in the large intestine, which means gas is produced. The more prebiotics, the more flatulence, cramping and diarrhea. Most people can handle 10-20 grams/meal, but some people complain of side effects with that amount.
So where does that leave us? See my final blog as I try to summarize the health benefits of these topics and try to make sense on what you can do on a daily basis.
Tuesday, May 31, 2011
Friday, May 27, 2011
PROBIOTICS - do they make the GRADE?
There are books on this topic. I am going to just give you an overview
1. Making the Grade
2. The probiotic microorganisms
3. Important health effects of probiotics
4. Safety of probiotics
5. Types of foods with probiotics
MAKING THE GRADE
For an organism to be considered a probiotic (and by extension, a probiotic food), it needs to have a positive effective on health in humans (not just rats!). In addition, it should be safe and nontoxic. The studies done have to be on the specific organism, not on a related species, because close "relatives" do not always have the same physiologic effect in humans. Other values that have to be taken into consideration include the number of viable organisms ingested to have the health effects and are they still effective at the end of the expiration date. And don't forget the age, health, gender and race of the person taking the probiotic can affect whether or not something works.
PROBIOTIC MICROORGANISMS
Lactobacilli -bacteria found in abundance in the gut of humans
Bifidobacteria - another group of bacteria found in abundance in the normal human gut.
Other probiotic organisms that are found in normal humans but in smaller amounts include some forms of enterococci, streptococci, lactococci, and some yeast.
HEALTH EFFECTS
The intestine is extremely involved in the immune system both through how it breaks down the foreign bodies that enter into it (food included) as well as its extensive lymphoid system. The balance of the different organisms in the intestine will change the pH, the production of substances that kill or allow the growth of different types of bacteria and weaken or strengthen the barrier of the intestinal mucosa. This is where the probiotics are able to enhance health.
There are many scientific studies that try to measure the health benefits. Some are done well, some are poorly done, some are difficult to do, and some are waiting to be done. As it now stands, based on the good studies, the scientific community generally accepts that probiotics do the following:
1. Decrease the symptoms of lactose intolerance
2. Prevent or reduce both rota virus and antibiotic-caused diarrhea.
3. Increase remission periods in people with inflammatory bowel disease
There are some studies that show conflicting reports, and the effects are only in certain groups:
1. Some regulation in gut motility (improvement in some groups with irritable bowel syndrome)
2. Improvement or resolution of allergies and atopy in infants, but not older patients
And then in some studies things work in the lab, but so far not in people
1. Cancer prevention
2. Decrease cholesterol and protection for heart disease
SAFETY
Probably the best way to think about this is that lactic acid bacteria and bifidobacteria have been used for millenia and have been safe. Also, when they have actually been looked at, there is no evidence that probiotic products are riskier than are similar products that do not have probiotics added to them. Also, studies done on patients with leukemia and HIV who were taking probiotics did not have increase infections with lactobacilli.
TYPES OF FOODS
Probiotic foods are different from probiotics in that that have to continue to maintain their efficacy throughout production and shelf life. They also have to be something that you want to buy which means that they look and taste good for most people.
Fermented Milk Products
Yogurt is the most popular type of probiotic food. Many yogurts on the market actually do not fit the criteria of being a probiotic. They do not have live cultures, or do not have the organisms that qualify as probiotics.
Hard cheese is difficult to produce as a probiotic, although fresh cheese is easier. Unfortunately, the manufacturing process of any cheese tends to kill off the bacteria. To date all the studies testing the effects of the cheese were done in animals and there are no marketable cheeses so far.
Other potential foods include ice cream and other sweets, but that kind of defeats the purpose in my mind. Vegetables have not been tested. There is some talk about spraying probiotics on salami, but no testing so far. There have been some studies of probiotic milk powder, but no information on its stability and efficacy. It could be used in powdered milk, formula etc. if it is successful.
BOTTOM LINE ON PROBIOTICS
Probiotics have scientifically been shown to be safe and have a positive health effect, but not as extensively as what has been claimed in the lay press. At this point, the only way to get it in food is through yogurt.
On to PREBIOTICS in the next blog.
1. Making the Grade
2. The probiotic microorganisms
3. Important health effects of probiotics
4. Safety of probiotics
5. Types of foods with probiotics
MAKING THE GRADE
For an organism to be considered a probiotic (and by extension, a probiotic food), it needs to have a positive effective on health in humans (not just rats!). In addition, it should be safe and nontoxic. The studies done have to be on the specific organism, not on a related species, because close "relatives" do not always have the same physiologic effect in humans. Other values that have to be taken into consideration include the number of viable organisms ingested to have the health effects and are they still effective at the end of the expiration date. And don't forget the age, health, gender and race of the person taking the probiotic can affect whether or not something works.
PROBIOTIC MICROORGANISMS
These organisms meet the following criteria: they are are not toxic or pathogenic, are originally from the guts of healthy people, and can pass through the stomach without losing their effectiveness before they get to the intestines.
Bifidobacteria - another group of bacteria found in abundance in the normal human gut.
Other probiotic organisms that are found in normal humans but in smaller amounts include some forms of enterococci, streptococci, lactococci, and some yeast.
HEALTH EFFECTS
The intestine is extremely involved in the immune system both through how it breaks down the foreign bodies that enter into it (food included) as well as its extensive lymphoid system. The balance of the different organisms in the intestine will change the pH, the production of substances that kill or allow the growth of different types of bacteria and weaken or strengthen the barrier of the intestinal mucosa. This is where the probiotics are able to enhance health.
There are many scientific studies that try to measure the health benefits. Some are done well, some are poorly done, some are difficult to do, and some are waiting to be done. As it now stands, based on the good studies, the scientific community generally accepts that probiotics do the following:
1. Decrease the symptoms of lactose intolerance
2. Prevent or reduce both rota virus and antibiotic-caused diarrhea.
3. Increase remission periods in people with inflammatory bowel disease
There are some studies that show conflicting reports, and the effects are only in certain groups:
1. Some regulation in gut motility (improvement in some groups with irritable bowel syndrome)
2. Improvement or resolution of allergies and atopy in infants, but not older patients
And then in some studies things work in the lab, but so far not in people
1. Cancer prevention
2. Decrease cholesterol and protection for heart disease
SAFETY
Probably the best way to think about this is that lactic acid bacteria and bifidobacteria have been used for millenia and have been safe. Also, when they have actually been looked at, there is no evidence that probiotic products are riskier than are similar products that do not have probiotics added to them. Also, studies done on patients with leukemia and HIV who were taking probiotics did not have increase infections with lactobacilli.
TYPES OF FOODS
Probiotic foods are different from probiotics in that that have to continue to maintain their efficacy throughout production and shelf life. They also have to be something that you want to buy which means that they look and taste good for most people.
Fermented Milk Products
Yogurt is the most popular type of probiotic food. Many yogurts on the market actually do not fit the criteria of being a probiotic. They do not have live cultures, or do not have the organisms that qualify as probiotics.
Hard cheese is difficult to produce as a probiotic, although fresh cheese is easier. Unfortunately, the manufacturing process of any cheese tends to kill off the bacteria. To date all the studies testing the effects of the cheese were done in animals and there are no marketable cheeses so far.
Other potential foods include ice cream and other sweets, but that kind of defeats the purpose in my mind. Vegetables have not been tested. There is some talk about spraying probiotics on salami, but no testing so far. There have been some studies of probiotic milk powder, but no information on its stability and efficacy. It could be used in powdered milk, formula etc. if it is successful.
BOTTOM LINE ON PROBIOTICS
Probiotics have scientifically been shown to be safe and have a positive health effect, but not as extensively as what has been claimed in the lay press. At this point, the only way to get it in food is through yogurt.
On to PREBIOTICS in the next blog.
Monday, May 23, 2011
Buyer Beware: Health Promises of Functional Food
"Let food by thy medicine and medicine be thy food" so said Hippocrates. If you search this phrase on the Internet you will find thousands of claims of how foods can cure you of everything. It reminds me of the days when men would travel around with magic potions that could cure whatever ails you. Literature and theatre abound with tales and songs of miracle elixirs. And there is an even longer history of the health-promoting aspects of certain foods.
For thousands of years fermented foods have been eaten throughout the world. Abraham's long life is attributed to eating sour milk. The Romans treated gastroenteritis with fermented milk products. But I am still a sceptic as I look at all the claims on the Internet. I decided to review the medical literature where there are more and more articles looking at food, and this topic specifically, and what it can do for health. I will try and summarize the many studies that I reviewed to make some sense out of all that's out there so that you can decide what, if anything, you what to spend your money on.
So today's blog will be an overview on what is a functional food and how scientists define prebiotics, probiotics and synbiotics. The next blogs will go into specifics about them and what the studies have shown and haven't shown about their effects on health. If there are a lot of comments and/or questions I will address them further.
FUNCTIONAL FOODS
When you look at the label on packaged food it gives you the nutritional value of the food (calories, vitamins, proteins, etc.) but it won't tell you its wellness-maintaining properties. It doesn't address issues of its potential medicinal benefits. But for a food to make the claim of being "functional" it should have some enhancement of health beyond its nutritional value.
I plan to focus this discussion on foods that have their effect on the gut. In a normal gut, you would want the organisms that promote good health to predominate over the organisms that are potentially harmful. Basically, the whole point of functional food is that after you eat this stuff, you will promote an increase number of healthy bacteria. Therefore the food has a function "beyond nutrition".
PREBIOTIC
A prebiotic was first defined in 1995 and then further refined over the years. Presently the accepted definition from the International Scientific Scientific Association for Probiotics and Prebiotics (ISAPP) meeting in 2008 is "A dietary prebiotic is a selectively fermented ingredient that results in specific changes, in the composition and/or activity of the gastrointestinal microbiota, thus conferring benefit(s) upon host well being and health." This means that certain functional foods are not digested by the person but will actually be fermented by selective intestinal bacteria and promote their growth. These bacteria are beneficial to the person's health.
PROBIOTIC
Although there are some variations in the definitions on what makes up a probiotic, they all agree that the probiotic microorganisms must be living and that scientifically there needs to be proven health effects. Probiotics are defined as actual microorganisms which get to the intestines in an active form and in a large enough quantity so that the can exert a positive effect on health. Although many people will use the term probiotics interchangeably with probiotic foods they are not the same thing. Probiotic foods are foods that also contain organisms (probiotics) that will give an additional health benefit beyond that of the nutritional content of the food.
SYNBIOTICS
Symbiotics are a mixture of probiotics and prebiotics which when added together are supposed to act "synergistically" by promoting the implantation of the live organism (probiotic) and improve its survival (prebiotic). For a food to be classified as a prebiotic or a probiotic, it has to be in certain quantities or concentrations. Food companies have been launching more and more products and want to promote the health benefits of their foods, but they cannot classify them in either category because they do not meet criteria. So what they are doing is putting both pre and pro biotics in their foods and labeling them as "synbiotics". Often these foods do not have enough pre and pro biotics in them to act in the synergistic way the companies state to have the claimed health benefits.
In the next blogs I will address the myriad of potential health benefits and look at what has been proved, disproved, shown in animals only and thought to be possible from food.
For thousands of years fermented foods have been eaten throughout the world. Abraham's long life is attributed to eating sour milk. The Romans treated gastroenteritis with fermented milk products. But I am still a sceptic as I look at all the claims on the Internet. I decided to review the medical literature where there are more and more articles looking at food, and this topic specifically, and what it can do for health. I will try and summarize the many studies that I reviewed to make some sense out of all that's out there so that you can decide what, if anything, you what to spend your money on.
So today's blog will be an overview on what is a functional food and how scientists define prebiotics, probiotics and synbiotics. The next blogs will go into specifics about them and what the studies have shown and haven't shown about their effects on health. If there are a lot of comments and/or questions I will address them further.
FUNCTIONAL FOODS
When you look at the label on packaged food it gives you the nutritional value of the food (calories, vitamins, proteins, etc.) but it won't tell you its wellness-maintaining properties. It doesn't address issues of its potential medicinal benefits. But for a food to make the claim of being "functional" it should have some enhancement of health beyond its nutritional value.
I plan to focus this discussion on foods that have their effect on the gut. In a normal gut, you would want the organisms that promote good health to predominate over the organisms that are potentially harmful. Basically, the whole point of functional food is that after you eat this stuff, you will promote an increase number of healthy bacteria. Therefore the food has a function "beyond nutrition".
PREBIOTIC
A prebiotic was first defined in 1995 and then further refined over the years. Presently the accepted definition from the International Scientific Scientific Association for Probiotics and Prebiotics (ISAPP) meeting in 2008 is "A dietary prebiotic is a selectively fermented ingredient that results in specific changes, in the composition and/or activity of the gastrointestinal microbiota, thus conferring benefit(s) upon host well being and health." This means that certain functional foods are not digested by the person but will actually be fermented by selective intestinal bacteria and promote their growth. These bacteria are beneficial to the person's health.
PROBIOTIC
Although there are some variations in the definitions on what makes up a probiotic, they all agree that the probiotic microorganisms must be living and that scientifically there needs to be proven health effects. Probiotics are defined as actual microorganisms which get to the intestines in an active form and in a large enough quantity so that the can exert a positive effect on health. Although many people will use the term probiotics interchangeably with probiotic foods they are not the same thing. Probiotic foods are foods that also contain organisms (probiotics) that will give an additional health benefit beyond that of the nutritional content of the food.
SYNBIOTICS
Symbiotics are a mixture of probiotics and prebiotics which when added together are supposed to act "synergistically" by promoting the implantation of the live organism (probiotic) and improve its survival (prebiotic). For a food to be classified as a prebiotic or a probiotic, it has to be in certain quantities or concentrations. Food companies have been launching more and more products and want to promote the health benefits of their foods, but they cannot classify them in either category because they do not meet criteria. So what they are doing is putting both pre and pro biotics in their foods and labeling them as "synbiotics". Often these foods do not have enough pre and pro biotics in them to act in the synergistic way the companies state to have the claimed health benefits.
In the next blogs I will address the myriad of potential health benefits and look at what has been proved, disproved, shown in animals only and thought to be possible from food.
Monday, May 16, 2011
Quiche Review
Top Quiche!
Food—there are no words to describe how I feel about it. I lead a very busy life and always look forward to enjoying a nice meal at home. It’s common knowledge in my home that when I’m not doing homework I’m watching Food Network or the Cooking Channel. I was given an interesting opportunity to evaluate two slices of quiche, made using the same recipe, prepared in different ways. The main ingredients included spinach, onion, and mild cheddar cheese. I was asked to compare and contrast the two slices of quiche. My real life opportunity to be a Top Chef judge!
I blindly tasted each slice, not knowing the differences between them. As I observed the two quiches, I was taken aback by their inviting and welcoming features. They were both beautifully baked and presented nicely on the plate. However, Quiche “A” appeared like it would be tastier than Quiche “B” because it looked more moist and creamier. I watched as the cheese slowly melted out and I was eager to try it. Quiche B looked a bit crispier and didn’t have as much of an inviting appearance. I sunk my fork into Quiche A first. It had a comforting, fresh aroma. As I tasted the quiche it was quite delicious, I must say; however, I felt that it was a bit too mushy. It left a creamy residue in my mouth that was a little too much for my liking. Immediately after I ate the bite of Quiche A, I was excited to try Quiche B because the creaminess of Quiche A made me want to try something crisper. This slice had a bit more crunch when I cut into it than Quiche A did, and although I don’t think of “crunchy” when I think of a quiche, I was intrigued by this characteristic. I sniffed the bite of quiche on my fork, and the ingredients smelled quite fresh -- more so than Quiche A. I took a bite and I sensed an uncharted combination of flavors I hadn’t ever tried before. The ingredients tasted fresher than the other one. Although, it tasted a little crunchier, I found it refreshing and it did not leave my mouth with a creamy residue. It was love at first bite! I slowly enjoyed Quiche B, thinking of nothing other than the delightful flavors and texture. Before I knew it, the crumbs of the perfectly cooked crust were the only remnants of the quiche on my plate.
Although Quiche A was a mighty contender to Quiche B, I felt the flavors in Quiche B were more prominent and resonated freshness. Overall, I felt that both quiches were lovely, but it all came down to the texture and the distinction between flavors. Since I enjoyed both of the slices, I feel lucky to have been asked to participate in this momentous test! I was later told that Quiche B was made with frozen spinach and ordinary onions (not the special ones from the Farmer’s Market). I was surprised that I chose it over the one with fresh spinach and sweet onions. But I was happy to know that it’s a recipe that I could easily follow myself.
There were some differences in technique as the reviewer alluded to which I will now elaborate on. Since Carla and I were making dinner for our families I changed my quiche to cater to my family's tastes. I used fresh, spring onions which have a sweeter, milder taste. I also used fresh, baby spinach which also is less bitter. As you can see by the slices, quiche A (my quiche) has less spinach and the onion is more finely chopped. I also took greater care to mix in the cheddar cheese. Carla has hers layered on top, giving it the less creamy, more crunch to it. Clearly, technique changes the outcome.
This whole "project" brings up some interesting, and important points for all parents.
1. Children prefer what they are used to.
This is extremely interesting and shows what an important influence you have on what your children eat. You can tell from the review that the flavors in our quiches were different. And in a previous post (Nana's Vegetable Soup), the kids again preferred what they were used to, not what would be considered the more sophisticated, gourmet-type cooking. Luckily, I have a thick skin, or about now I would be questioning my cooking skills.2. The sooner you introduce your child to varied and healthy foods, the better and more nutritious their diet will be. (When my daughter was 3 we ordered her an appetizer of mussels for her dinner. The waiter was amazed as she worked her way through the whole thing. But she had been eating them since she was little and it was (and is) one of her favorite foods.)
3. Get the kids in the kitchen.
4. Cooking is more fun when done with others. Carla said she enjoyed our afternoon together and would like to do it again. As she reads this she will now find out I have decided to make this an on-going project of the blog entitled "COOKING WITH CARLA".
We'll try to do this once a month, Julia Child style. For those of you who remember her PBS cooking show, she had a REAL reality TV show and would record everything; including mistakes. We will describe what happens to real people who don't cook, so that you can see what happens and see that everything can (usually) still be edible. Maybe we can even get our judge back. (Although at the rate I'm going, I may get kicked off the blog!)
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