This study reviews all of the previous studies, which is part of the definition of a systematic review, so it is the most current summary of the evidence. And since for every medical question there is almost always disagreement between individual studies, reviews such as this are useful in giving us an overview of what the reearch as a whole says. You can find positive and negative studies on any subject, so such overviews help us decide if the evidence is stronger for or against something. Of course, new research is always ongoing, so in a couple of years if there are a significant number of additional studies, another review will have to be done.
And other reviews exist that look at subsets of the larger question, and those reviews might answer specific questions not asked in this one.
And of course your’e correct this only addresses Vit D supplementation, and each single supplement, as well as combinations such as mutivitamins, have to be addressed separately. There have been a few other such systematic reviews cited in this thread such as
Vitamin and Mineral Supplements in the Primary Prevention of Cardiovascular Disease and Cancer: An Updated Systematic Evidence Review for the U.S. Preventive Services Task Force]
as well as a number of reviews and primary articles I have collected elsewhere]
The devil is in the details, and it’s a complex subject for sure!
I’m curious. Perhaps the medical experts here can answer my concerns.
- Is it true that as one gets older, his/her intestines don’t absorb quite as efficiently as do those of younger people?
- Do older people need fewer calories, both because of decreased activity and slower metabolism?
- Do older people’s internal chemistry doesn’t function as well as the chemistry of younger people?
- We are told that to avoid obesity, we should eat less than we did as we did when we were younger. If we were getting an adequate amount of micro-nutrients then, how do we assure that we are still getting enough even though we are eating significantly less?
Thanks for your expert advice.
Occam
Obviously, I’m no expert on human medicine, so I’ll defer to macgyver. By coincidence, however, I just wrote a paper on malnutrition and infectious disease in the elderly for a class I’m taking as part of my master’s in epidemiology, and it touches on the issue of nutrition and aging, as well as the subject of the pros and cons of supplementation. I’ll email it to you (and anyone else interested) in case it has anything useful for you on these questions.
I don't think the two Ms are claiming that the supplements are evil, Vy, just that no one needs them because all of Americans get adequate amounts of all the supplements in our diets so we're wasting money by taking them. After all, we have to recognize the value of the fast food industry in their efforts to provide low fat, low calorie, high quality foods which supply all our nutritional needs to everyone. :lol: Of course, the response to this is: Americans should work to eat an adequate diet rather than the junk foods. And that's true, just as is: Americans should all be atheistic, liberal, humanists who care for and respect each other. OccamI would love to see what would happen to the population if flour, rice, milk, cooking oils, fruit juices and cereal had all of their supplementation/fortification removed. I mean from a statistical sense in regards to increase of disease. I wonder if studies could be done regarding this. Studies have already been done by WHO in regards to why they are fortifying foods. Either voluntarily or through government regulation. From Wikipedia: The WHO and FAO, among many other nationally recognized organizations, have recognized that there are over 2 billion people worldwide who suffer from a variety of micronutrient deficiencies. In 1992, 159 countries pledged at the FAO/WHO International Conference on Nutrition to make efforts to help combat these issues of micronutrient deficiencies, highlighting the importance of decreasing the number of those with iodine, vitamin A, and iron deficiencies.[2] A significant statistic that led to these efforts was the discovery that approximately 1 in 3 people worldwide were at risk for either an iodine, vitamin A, or iron deficiency. Although it is recognized that food fortification alone will not combat this deficiency, it is a step towards reducing the prevalence of these deficiencies and their associated health conditions.[5]
I'm curious. Perhaps the medical experts here can answer my concerns. 1. Is it true that as one gets older, his/her intestines don't absorb quite as efficiently as do those of younger people? 2. Do older people need fewer calories, both because of decreased activity and slower metabolism? 3. Do older people's internal chemistry doesn't function as well as the chemistry of younger people? 4. We are told that to avoid obesity, we should eat less than we did as we did when we were younger. If we were getting an adequate amount of micro-nutrients then, how do we assure that we are still getting enough even though we are eating significantly less? Thanks for your expert advice. :) OccamThese are actually very complex questions and I really am not prepared to give a comprehensive answer without reviewing this subject. I can give you some basic information though 1) As we get older we do absorb some things less efficiently but it would be simplistic to say that applies to all substances since we use different mechanisms to absorb different molecules. Digestion actually begins in the mouth with both the mechanical breakdown of food by chewing as well as some initial action of enzymes in found in saliva. Complex molecules like proteins and starches for example need to be broken down first into simpler molecules by enzymes. Once that happens they must then be transported across the the intestinal mucosa for transport throughout the body. Some substances like B12 for example require special transport mechanisms B12 must be first bound to intrinsic factor in the stomach which allows tissue in the small intestine to latch onto the B12 and absorb it. In order for B12 to bind to intrinsic factor it must first be released from the food it is bound within and this requires acid. As we get older we tend to produce less acid and this can lead to an increased risk of B12 malabsorption. There may be other substances with other mechanisms of age related malabsorption but this is just one example. 2) For the most part the answer to this question is yes. Metabolism on average does decrease with age as does activity levels but there are of course exceptions and individual variation. In addition there are disease states such as infections and cancer and situations such as surgery which may increase calorie requirements. 3) Not really sure how to answer this question. I am inclined to say yes as the accumulation of DNA damage over time causes derangement of many proteins and this most likely includes enzymes that catalyze reactions in biochemical pathways, but as the subject is a bit to broad and I have never really researched this issue I can;t really answer in more detail. 4) While we may eat less as we get older we are doing so because our requirements are less. Our requirements are less because cell turnover is slower, muscle mass is lower and one would think that as a result some of our nutrient requirements are less as well. This is a complex question though because as I mentioned above some nutrients are absorbed less effectively in some older patients so reduced needs and reduced consumption may not necessarily balance each other. If the purpose of these questions is to construct a logical opinion about whether older people should take vitamin supplements its really an ineffective way to get the answer. There are too many variables and too many unknowns. The only effective way of answering the question is by doing randomized trials and looking at outcomes. You may want to search pubmed for more information on the subject. You may want to email mckenzie for a copy of his paper as well since it sounds like he may have done a lot of the work for you.
I’m far from an expert, but I read somewhere, (or processed something that I read somewhere, to understand) that after a certain age we need less protein, but then as we get even older we’re better off with increased protein, again. If this is true, Occam, you may be free to be more carnivorous, than some of us medium-old folks.
HERE] is an article on the history of food fortification. Interesting subject I haven’t previously thought much about.
HERE] is an article on the history of food fortification. Interesting subject I haven't previously thought much about.Yes. Interestingly the fortification of foods lies on the halfway point of your's and my continuing debate on the subject of supplementation. You make excellent points about evolving knowledge of the role of vitamins, and vitamin supplements on the human body as far as metabolism, prevention, and general health, dosages, as well as what was thought and what is now known on what vitamins do for us beneficially and harmfully. Obviously I make no claims about the efficacy for supplements to prevent specific disease. Only in the sense of whole nutrition do I treat the idea of disease prevention. Whether or not that nutrition is supplemented or "natural". Obviously there is no doubt that nutrition is one of the key components of disease prevention. That leads us to the ambiguous comments that have been made here concerning " a normal diet" and such, that MacGeyver and you have tried to level at me regarding the uselessness of supplements. It is quite clear that worldwide and here in the US, many people do not have a normal diet for many different reasons.(especially if foods were NOT fortified) The discussion of food fortification(supplementation) brings light to bear on both of our arguments. I'm sure as the excellent article you cited here reveals, that even food fortification is an evolving science.
Latest review of the evidence concerning Vitamin D and calcium supplements ]finds little evidence of consistent relationship between these vitamins and health.
In solid agreement with the findings of the original report, the majority of the findings concerning vitamin D, alone or in combination with calcium, on the health outcomes of interest were inconsistent. Associations observed in prospective cohort and nested case-control studies were inconsistent, or when consistent, were rarely supported by the results of randomized controlled trials. Clear dose-response relationships between intakes of vitamin D and health outcomes were rarely observed. Although a large number of new studies (and longer followups to older studies) were identified, particularly for cardiovascular outcomes, all-cause mortality, several types of cancer, and intermediate outcomes for bone health, no firm conclusions can be drawn…it is difficult to make any substantive statements on the basis of the available evidence concerning the association of either serum 25(OH)D concentration, vitamin D supplementation, calcium intake, or the combination of both nutrients, with the various health outcomes because most of the findings were inconsistent.
Wow 929 pages. Thanks for the link :-P. Seriously though this only shows the level of interest in this vitamin over the past few years. It has become a significant and frequent topic of discussion. I wish I could say the medical community was on board with the findings of the document you linked to but unfortunately a lot of my colleagues have bought into the idea that Vit D is the solution for everything that ails you despite a lack of good evidence to support these ideas.
It has become common place for physicians to include Vit D levels as part of the routine blood work on annual exams and then supplement with large doses of Vit D if they are low despite the fact that there are no studies at all which examine this approach for safety and benefit.
That’s the crazy world we live in though. Physicians and patients are allowing the media to set the tone and getting ahead of the evidence.
Wow 929 pages. Thanks for the link :-P. Seriously though this only shows the level of interest in this vitamin over the past few years. It has become a significant and frequent topic of discussion. I wish I could say the medical community was on board with the findings of the document you linked to but unfortunately a lot of my colleagues have bought into the idea that Vit D is the solution for everything that ails you despite a lack of good evidence to support these ideas. It has become common place for physicians to include Vit D levels as part of the routine blood work on annual exams and then supplement with large doses of Vit D if they are low despite the fact that there are no studies at all which examine this approach for safety and benefit. That's the crazy world we live in though. Physicians and patients are allowing the media to set the tone and getting ahead of the evidence.No, it's only 28 pages. I read the article and it implies that there is some benefit to supplementation and fortification of foods. This particular article does not cite any research that says they are of no use, but suggests further research. This website from the National Institutes of Health says Vitamin D supplements are effective for several conditions. http://www.nlm.nih.gov/medlineplus/druginfo/natural/929.html My own doctor said my Vit D levels are low and suggested I take a Calcium and D supplement. I think most patients would take the supplements if their doctor said a blood test indicated a deficiency. I agree that supplements may not be doing much and are probably being overprescribed. But what is a patient to do when his or her doctor prescribes a supplement? Most patients are not going to wade through medical reports and will take the doctor's advice. Lois
My own doctor said my Vit D levels are low and suggested I take a Calcium and D supplement. I think most patients would take the supplements if their doctor said a blood test indicated a deficiency. I agree that supplements may not be doing much and are probably being overprescribed. But what is a patient to do when his or her doctor prescribes a supplement? Most patients are not going to wade through medical reports and will take the doctor's advice. LoisLois I agree that its difficult to know what to do when your doctor prescribes something and you are not sure if its the right thing to do. I am not suggesting that you ever ignore your doctors advice but I am suggesting that you ask questions. What I advise people is to ask your doctor if he or she can refer you to some studies or recommendations from professional organizations that support their approach. The USPSTF is a a good source for recommendations. They are a governmental agency made up of experts in the field who review all of the current literature on a given subject and then come up with a recommendation based on that evidence. In regards to Vit D their recommendation can be found here], but to quot from it "Screening for Vitamin D Deficiency in Adults Potential Benefits and Harms of Screening for Vitamin D Deficiency The Task Force reviewed studies on the benefits and harms of screening for vitamin D deficiency. They found that there is not enough evidence to determine whether screening healthy adults leads to improvements in health. They also did not find enough evidence to understand the potential harms of screening for vitamin D deficiency. Because current scientific evidence does not clearly tell us what an unhealthy blood level of vitamin D is, the screening test may suggest that some people are vitamin D deficient when they are actually healthy. These people may get vitamin D treatment when they do not really need it." Unfortunately lots of physicians do things either because patients ask for something or because they hear about it from unreliable sources like the mainstream media or because colleagues are doing it. Such is the case with Vit D measurements. Lots of doctors are measuring and treating vitamin D levels today. We have gotten into this situation with Vit D because a number of studies over the past few years seem to have shown a correlation between low Vit D levels and a number of diseases. These studies have not shown a causative ink, only a correlation. Many have jumped to the conclusion that these studies are enough and we dont need to show causation hence the rush to measure levels on patients but this logic is flawed for several reasons 1) There are NO studies which demonstrate that measuring and treating low levels of Vit D is either beneficial or safe. 2) Safety is an important issue as supplementation of other vitamins has been found on occasion to be harmful. Vit A supplementation can cause an increase in lung cancer and Vit E supplementation has been shown to increase the risk of prostate cancer. 3) No one knows what level of Vit D is "healthy". The current "normal" level is 30-100 in most labs but this normal range is somewhat arbitrary and no one really knows what level is the best level for good health. 4) We don't even now if blood levels of Vit D accurately portray body stores of Vit D. Vit D is a fat soluble vitamin and is stored in body fat and the liver. These stores are not always in equilibrium with the vitamin D found in our blood such that blood levels may not be an accurate measure of total body Vit D. Among my own patients I did Vit D levels for a few months out of curiosity among those who asked for it ( I have since stopped offering this test). Among the 100 patients I tested only a couple had normal levels. Other studies have shown abnormal levels in 25-80% of patients. If we are gong to begin a program of Vit D testing and treatment on a population of healthy people and the vast majority are then going to be treated we need far better evidence than we currently have to verify that this approach will cause more benefit than harm. Again, I am not asking you to ignore your doctors advice, but ask him about this and ask him about the USPSTF recommendation. He may be surprised or not even be aware of it since the whole world around him seems to have accepted Vit D testing and treatment as "the thing to do".
Lois,
MacGyver was responding to the most recent post I made (Post #428) which contained a link to a long, comprehensive evidence review. The article you read was from Post # 426, which was ONLY talking about fortification of foods. The longer review reports the results of studies done over many years in thousands of people, and generally finds no evidence of benefit for Vitamin D screening or supplementation in almost all of the uses commonly recommended. While one can never prove something is never helpful without testing an infinite number of possible individuals, doses, uses, etc., the failure to find a benefit after extensive research like this is pretty good evidence there is little or no benefit to find.
Lois, MacGyver was responding to the most recent post I made (Post #428) which contained a link to a long, comprehensive evidence review. The article you read was from Post # 426, which was ONLY talking about fortification of foods. The longer review reports the results of studies done over many years in thousands of people, and generally finds no evidence of benefit for Vitamin D screening or supplementation in almost all of the uses commonly recommended. While one can never prove something is never helpful without testing an infinite number of possible individuals, doses, uses, etc., the failure to find a benefit after extensive research like this is pretty good evidence there is little or no benefit to find.Ok, thanks. Yes, that one iS 929 pages. I wonder who would read it. Certanly not laymen. Probably not even most physicians! Lois
My own doctor said my Vit D levels are low and suggested I take a Calcium and D supplement. I think most patients would take the supplements if their doctor said a blood test indicated a deficiency. I agree that supplements may not be doing much and are probably being overprescribed. But what is a patient to do when his or her doctor prescribes a supplement? Most patients are not going to wade through medical reports and will take the doctor's advice. LoisLois I agree that its difficult to know what to do when your doctor prescribes something and you are not sure if its the right thing to do. I am not suggesting that you ever ignore your doctors advice but I am suggesting that you ask questions. What I advise people is to ask your doctor if he or she can refer you to some studies or recommendations from professional organizations that support their approach. The USPSTF is a a good source for recommendations. They are a governmental agency made up of experts in the field who review all of the current literature on a given subject and then come up with a recommendation based on that evidence. In regards to Vit D their recommendation can be found here], but to quot from it "Screening for Vitamin D Deficiency in Adults Potential Benefits and Harms of Screening for Vitamin D Deficiency The Task Force reviewed studies on the benefits and harms of screening for vitamin D deficiency. They found that there is not enough evidence to determine whether screening healthy adults leads to improvements in health. They also did not find enough evidence to understand the potential harms of screening for vitamin D deficiency. Because current scientific evidence does not clearly tell us what an unhealthy blood level of vitamin D is, the screening test may suggest that some people are vitamin D deficient when they are actually healthy. These people may get vitamin D treatment when they do not really need it." Unfortunately lots of physicians do things either because patients ask for something or because they hear about it from unreliable sources like the mainstream media or because colleagues are doing it. Such is the case with Vit D measurements. Lots of doctors are measuring and treating vitamin D levels today. We have gotten into this situation with Vit D because a number of studies over the past few years seem to have shown a correlation between low Vit D levels and a number of diseases. These studies have not shown a causative ink, only a correlation. Many have jumped to the conclusion that these studies are enough and we dont need to show causation hence the rush to measure levels on patients but this logic is flawed for several reasons 1) There are NO studies which demonstrate that measuring and treating low levels of Vit D is either beneficial or safe. 2) Safety is an important issue as supplementation of other vitamins has been found on occasion to be harmful. Vit A supplementation can cause an increase in lung cancer and Vit E supplementation has been shown to increase the risk of prostate cancer. 3) No one knows what level of Vit D is "healthy". The current "normal" level is 30-100 in most labs but this normal range is somewhat arbitrary and no one really knows what level is the best level for good health. 4) We don't even now if blood levels of Vit D accurately portray body stores of Vit D. Vit D is a fat soluble vitamin and is stored in body fat and the liver. These stores are not always in equilibrium with the vitamin D found in our blood such that blood levels may not be an accurate measure of total body Vit D. Among my own patients I did Vit D levels for a few months out of curiosity among those who asked for it ( I have since stopped offering this test). Among the 100 patients I tested only a couple had normal levels. Other studies have shown abnormal levels in 25-80% of patients. If we are gong to begin a program of Vit D testing and treatment on a population of healthy people and the vast majority are then going to be treated we need far better evidence than we currently have to verify that this approach will cause more benefit than harm. Again, I am not asking you to ignore your doctors advice, but ask him about this and ask him about the USPSTF recommendation. He may be surprised or not even be aware of it since the whole world around him seems to have accepted Vit D testing and treatment as "the thing to do". Thanks. That makes sense. In my case the laboratory checked my D levels without my asking for it. Presumably my doctor directed them to do this--also without my request. I was already skeptical of this because a few friends said their doctors tested for Vit D levels and recommended supplements. One said her doctor retested her blood Vit D level after she took the supplements he recommended and said the level was still not high enough, so ordered an even higher dose of Vit D. This made me suspicious about the practice of testing for Vit D levels. Unfortunately my friend is not a skeptic and follows her doctor's advice unquestioningly and looks askance at any suggestion that her doctor might be following a poor protocol. So do most of my friends. So I guess that's where the problem lies. I will take your advice amd question my doctor for studies and recommendations. I guess many doctors are as easily influenced by the latest fads as the lay public is. Lois
Many doctors are businessmen.
Most doctors are ethical.
How many doctors out there, that are businessmen and unethical? This is a rhetorical question.
We all have seen/read about doctors getting paid by pharma representatives in pretty much every country:
http://www.news.com.au/lifestyle/health/hundreds-of-doctors-paid-thousands-to-advise-drug-companies-on-their-products/story-fneuzlbd-1226673435918
Many doctors are businessmen. Most doctors are ethical. How many doctors out there, that are businessmen and unethical? This is a rhetorical question. We all have seen/read about doctors getting paid by pharma representatives in pretty much every country: http://www.news.com.au/lifestyle/health/hundreds-of-doctors-paid-thousands-to-advise-drug-companies-on-their-products/story-fneuzlbd-1226673435918John this makes great headlines but its grossly misleading. "Hundreds of doctors paid thousands" sounds awful until you realize a few things. Yes there are a few hundred doctors who received large payments but that's a few hundred out of nearly 900,000 doctors actively practicing in the U.S. (http://kff.org/other/state-indicator/total-active-physicians/) The small number of doctors who are being paid to do this are not being paid to prescribe the drug. They are being paid to give talks to other physicians about the drugs. Some physicians are researchers so that the money they receive may be simply the salary they are earning from their employer (pharma). There is nothing ethically wrong with a physician doing that especially since physicians are far more qualified to do these jobs than non-physicians who don't understand the biology and pharmacology. If that doctor then preferentially prescribes that drug to his patients without informing the patient of the potential conflict of interest then that would indeed be unethical. The implication of these stories is that doctors in large numbers are taking money from pharma as a payoff for prescribing their drugs but the numbers do not support that headline. The numbers only show a small percentage of doctors taking significant amounts of money from pharma and its unclear to what extent this has affected the prescribing patterns of those few physicians. If you are really worried check your own physician at http://projects.propublica.org/docdollars/. When you do keep in mind that amounts of $300-400 may represent 2 or 3 lunches brought to the office for staff by reps during the year. While I don't agree with this practice I seriously doubt most physicians are going to change theri prescribing habits because their staff got a couple of sandwiches.
My own doctor said there is no effective substitute for statins, but if you can get your cholesterol levels down with vitamins, I might try it myself because my body does not tolerate statins. LoisI'll let you know what happens with my cholesterol levels. I am not overly optimistic. But even if my levels turn out to look better, it doesn't necessarily follow that it would work for you. I could just be an outlier. Lois, as I said I would let you know: For 7 months I took high doses of fish oil. I attribute the changes in my cholesterol levels to this, as I made no significant changes to diet or activity level or lifestyle. My total cholesterol increased from 227 to 242. My triglycerides went from 217 (high risk for heart disease) to 181 (borderline risk for heart disease. My Total Cholesterol to HDL ratio went from 5.28 (low moderate risk) to 4.6 (low risk). My LDL/HDL went from 3.28 (low average risk) to 3.5 (high average risk). So the results were a mixed bag, but in terms of cholesterol, I think my risk for heart disease, overall, went down slightly. I am a big guy, and I was taking at least 4000 mg of fish oil a day for part of the 7 months, and as much as 7200 mg for some of the time. Generally, my understanding is that a dosage of greater than 4000 mg a day of fish oil may be associated with a greater risk of stroke. So I am now taking only 4000 mg. per day.
Tim,
Unfortunately, this sort of personal experiment isn’t as helpful as you might think. For one thing, the magnitude of the changes you report is of questionable clinical significance. Also, since there is normally quite a bit of random variation in these values from one measurement to another, it would take a lot more data to see if this truly represents a consistent trend. Finally, these are proxy markers, useful only to the extent that they correlate with clinical disease. We don’t, ultimately, care what our lipid values are but what our chances of developing cardiovascular disease are, and the lipid values are only useful if they help us predict this. So to know whether or not the supplement is “working,” we would have to establish that these changes are real and sufficient to affect your risk of clinical disease.
It is, of course, impossible to know this from any study of one individual, which is why we do large-scale clinical trials. Ultimately, whether these numbers mean anything will be determined by what such trials say about the effect of fish oils on actual disease in the population, and whether there is net benefit or harm or no net effect at all. All of this doesn’t mean you are wrong to take them, only that it would be wrong to draw any conclusions about their effects from a couple of lipid panels like this.
Adding to McKenzie’s comments on the variability found in routine cholesterol testing. Many people don;t realize that no measurement is ever perfectly precise. Such precision is technically impossible to achieve. There is always some degree of imprecision. IN the case of blood tests if we were to take your sample and put it in three different tubes and send all of them to the same lab we would not get the same results on each one. The margin of error for these tests can vary depending on the method used and the substance being measured. Precision can also be affected by the absolute number. Values that are at the extremes tend to have higher levels of imprecision.
Its difficult to find good information on the precision of cholesterol measurements because there are a number of different techniques that are used but I have seen levels of imprecision of about +/- 3-5% quoted for a number of cholesterol testing methods. That means that an LDL of 130 isn’t really 130. What it really means is that there is 95% chance that your LDL is between 123.5 and 136.5.
In addition to lab precision some of these values fluctuate significantly from one day to the next. The best example is the Triglyceride number. I have seen Triglycerides change by 300 points in the course of a few days. Unlike other cholesterol numbers triglyceride levels are affected far more by carbohydrate intake than fat intake. After a carbohydrate rich meal there can be a rapid and dramatic increase in the triglyceride levels in the blood but even fasting triglyceride levels can change dramatically form one day to the next.