So what are typical deficiencies in the American population? Women are at greater risk for iron and vitamin A deficiency, especially if they are pregnant. Vegans & vegetarians may become b12 deficient. Black skinned people are at greater risk for vitamin D deficiency because the "melanin in the skin diminishes the ability to synthesize Vitamin D from the sun". The elderly usually experience a decline in the gut absorption of micro-nutrients: "The age-related decline in the capacity to absorb calcium [56] appears due to a gut-resistance to the action of 1,25- dihydroxyvitamin D3 resulting from a loss of vitamin D receptors in the duodenal mucosa [57]". The elderly may be at risk for vitamin b6, b12, d and calcium deficiency.
The American Centers for Disease Control and Prevention's nutrition reports (CDC.gov) is "a series of publications that provide ongoing assessment of the U.S. population's nutrition status by measuring blood and urine concentrations of biochemical indicators".
They found that between 2003 and 2006:
"Of all the nutrients listed, the most people had vitamin B6, iron, and vitamin D deficiencies, and the fewest people had vitamin A, vitamin E, and folate deficiencies." [...] "However, for most nutrition indicators, deficiencies varied by age, gender, or race/ethnicity and could be as high as nearly one third of certain population groups.".
This should give you a general idea of what you might be deficient in. The best way to be 100% sure of your micronutrient levels, is getting a blood test.
This brings us to RDA. Every country gives recommendations for micronutrient intakes. These RDAs are divided into age groups, and are designed for the general population. The problem here is that athletes usually have higher requirements for minerals (as well as fluids and macronutrients - but that is beyond the scope of this RR). Furthermore, the RDAs are usually enough to avoid deficiency, but being non-deficient is not the same as having optimal micronutrient levels, and this is especially true for athletes.
"For active individuals a marginal deficiency in the nutrients may impact the body's ability to repair itself, operate efficiently and fight disease, said Melinda Manore, researcher in the Colleges of Agricultural and Health and Human Sciences." [...] "The stress on the body's energy producing pathways during exercise, the changes in the body's tissues resulting from training, an increase in the loss of nutrients in sweat, urine and feces during and after strenuous activity and the additional nutrients needed to repair and maintain higher levels of lean tissue mass present in some athletes and individuals may all affect an individual’s B-vitamin requirements, said Manore"Larry Kenney from Pennsylvania State University states:
"The 2004 recommendations on water and sodium intake from the Institute of Medicine (IOM) of the National Academy of Sciences are targeted primarily at sedentary Americans. These guidelines for water and salt intake should not be applied to athletes. Athletes who follow the IOM recommendations to the letter may actually put themselves at risk for unintended decreases in performance or even untoward health consequences."Weightlifting athletes may be particularly prone to the negative effects of vitamin D deficiency, because calcium requires vitamin D for optimal absorption. If absorption of calcium is hindered:
"Low vitamin D increases bone turnover, which increases the risk for a bone injury, like a stress fracture." [...] "vitamin D [...] also aids in regulation of electrolyte metabolism, protein synthesis, gene expression, and immune function [10,28]. These vital functions are essential for all individuals, especially the elite and recreational athlete."An athlete may decide to supplement vitamin D. Unknowingly, he purchases D2: "Vitamin D3 increases the total 25(OH)D concentration [...] Vitamin D2 supplementation was associated with a decrease in 25(OH)D3,"
This goes to show that there are different forms of micronutrients. These forms have different bioavailabilities and effects on the body. For example, magnesium oxide is maybe the most commonly supplemented form of magnesium. The problem is that "magnesium oxide may have an absorbable magnesium potency as low as 4%. 7 8". I could write for days about micronutrient forms and bioavailability, but to keep it succinct: multivitamins are usually filled with the cheapest and worst forms of vitamins and minerals. If you want to learn more about magnesium check out this post. To get more information about bioavailability check this out.
This brings us to the concept of antinutrients:
"Antinutrients in foods are responsible for deleterious effects related to the absorption of nutrients and micronutrients. However, some antinutrients may exert beneficial health effects at low concentrations.".
A very potent antinutrient is phytic acid. It is usually found in large concentrations in seeds, nuts, grains, legumes. "phytic acid [has the] ability to bind to essential minerals such as iron, zinc, calcium, and magnesium in the digestive tract and inhibit their absorption by the body.1,2". A consequence of this is that if a person is consuming a meal rich in phytic acid along with his daily multi, the minerals in the multi may be rendered less useful. The good news is that vitamin C partly counteracts the negative effects of phytic acid
More info on phytic acid
There are other factors that limit micronutrient absorption. These factors are the interactions between the nutrients, called vitamin and mineral antagonism and synergy 1 2. Micros that have synergy, enhance each other’s uptake (i.e. Vit D enhances calcium uptake, Vitamin C enhances iron uptake). There is also antagonism, whereby micros inhibit absorption of other micros. For example calcium interferes with iron absorption, zinc uptake is hindered by minerals such as cal, mag, iron, because they share a transporter.
The takeaway here is that if you fill a multivitamin with micro antagonists, they will compete for absorption and hinder uptake levels.
The last part of the introduction deals with what I call the size paradox of multivitamins. Simply put, it is impossible to squeeze (common values) 400mg of magnesium, 600mg of calcium, 14mg iron, 10mg zinc, 500iu vitamin d, 500mg vitamin c, all the b vitamins, trace minerals, etc. into a small tablet). I have a bottle of Magnesium citrate 100mg tablets, and each tablet is twice the size of my multi.
"12 multivitamins provided less vitamin A, vitamin C, or folate, or than claimed, some with less than 30% of the listed amounts. These include a prenatal vitamin and products for men, adults (general), seniors, and even pets."
Summary of introduction
- Common micronutrient deficiencies are: Vitamin D, iron, B6. Deficiency prevalence is population based (age, sex, skin color, lifestyle)
- Multivitamins are usually filled with the cheapest and worst forms of vitamins and minerals
- Reaching RDAs may prevent deficiency, but may not necessarily give you optimal levels
- Athletes need more micros than sedentary individuals
- Antinutrients and micronutrient antagonism severely hinder the absorption rates and bioavailability of MVs
- The minerals and vitamins found in MVs won't physically fit into a neat little pill
- Companies may lie on the contents label (goes for all supplements)
Summary of the meta-analysis (scroll down to see the studies)
- Antioxidants such as vitamin C and E may help fight cancer (but they could also hinder athletic performance improvements)
- Most research is done on the elderly
- There is no clear consensus because of contradictory evidence. However, the majority of the evidence points towards no effect
- Smokers may want to avoid MVs (especially ß-carotene)
- High doses of fat-soluble vitamins, such as vitamin A can be dangerous. Always check the bottle contents!
Final thoughts
Research does not support the hypothesis that MVs give health benefits. This does not mean that targeted or isolated supplementation is useless! For example, vitamin D3 supplementation has been shown to increase hormonal levels of vitamin D. You should probably figure out what you're deficient in and do targeted supplementation instead of buying a MV that probably won't do much for your health.
Part II - Studies
Before looking at the studies, we must identify the possible sampling biases of multivitamin research. It is possible that people who take multivitamins do so as a way to self-medicate, because they feel unhealthy or know they have unhealthy lifestyles. It could also be the effect of marketing. In most of the studies I reviewed, the participants were aged 50+. This is an issue because they do not represent the entire population. Lastly, studies usually rely on self-reported questionnaires. The risk here is that people lie or modify the truth.
I've tried to represent both sides of the debate as fairly as possible. I excluded studies with few participants, unclear methods, obvious spelling errors in the abstract (...), paid research (supplement marketing), very short trials, or generally poor design.
Example of excluded study with spelling errors, short trial, and likely paid
Example of excluded study because of purely self-reported statistics
Example of excluded study because low N and (relatively) short trial
Studies with evidence supporting multivitamin health benefits
Multivitamin Use and Risk of Cancer and Cardiovascular Disease in the Women's Health Initiative Cohorts
- Published: 2009
- Time period: 1993-2005
- Participants: 161 808
- Age: 50 to 79
- Inclusion criteria: postmenopausal women
- Exclusion criteria: alcoholism, drug dependency, dementia.
A total of 41.5% of the participants used multivitamins.
How they documented:
Dietary supplement data were collected during in-person clinic visits. Women brought supplement bottles to the baseline clinic visit and to annual visits thereafter in the CTs and to the baseline and 3-year visits in the OS.What they documented:
We documented cancers of the breast (invasive), colon/rectum, endometrium, kidney, bladder, stomach, ovary, and lung; CVD (myocardial infarction, stroke, and venous thromboembolism); and total mortality.What they found:
In this large cohort of postmenopausal women, we observed no overall associations between multivitamin use and risk of several common cancers or CVD. There were also no associations between multivitamin use and total mortality. Risk estimates did not materially change when stratified by class of multivitamins, with the exception of a possible lower risk of MI among users of stress-type supplements [STRESS SUPPLEMENTS = STACKED SUPPLEMENTS]. Many stress supplements include high doses of folic acid and other B vitamins; previous studies have supported a protective role for folic acid in relation to CVD and its antecedent risk factors.26,34- 36Limitations: Only postmenopausal women were tested, only some cancers and risk conditions were tested.
Multivitamin use and the risk of myocardial infarction: a population-based cohort of Swedish women
- Published: 2010
- Time period: 1997-2007
- Participants: 31 671 (no CVD) + 2262 (with CVD)
- Age: 49–83
- Inclusion criteria: Female
- Exclusion criteria: Cancer, diabetes
How they documented:
Women completed a self-administered questionnaire in 1997 regarding dietary supplement use, diet, and lifestyle factors.What they documented:
In the primary analyses we excluded 2262 women with a diagnosis of cardiovascular disorders
We also performed separate analysis to examine the association between multivitamin use and MI among those 2262 women with history of CVD
In the current study, we evaluated the effect of multivitamins with and without minerals on the risk of MIWhat they found:
In this large, prospective cohort of women we observed a lower risk of MI among women with no history of CVD at baseline who were using either multivitamins alone or multivitamins in combination with other supplements. The association was stronger among women who used multivitamins for =5 y. The risk did not differ substantially when we stratified by factors such as age, smoking status, BMI, alcohol consumption, and hypertension.Limitations: Only older women
Multivitamin-mineral use is associated with reduced risk of cardiovascular disease mortality among women in the United States
- Published: 2015
- Time period: 1988–2011 (18 year follow-up)
- Participants: 8678
- Age: >40
- Inclusion criteria: Females only, "NHANES III is a nationally representative, cross-sectional survey that uses a stratified, MVstage probability design to obtain a nationally representative sample of the civilian, noninstitutionalized US population".
- Exclusion criteria: pregnant and lactating women, chronic kidney disease, missing supplement information, CVD, stroke, or congestive heart failure
NHANES III obtained data on medication use and health history by questionnaireWhat they documented:
NHANES measured participants? demographic characteristics and health status and history, including dietary supplement use, during the personal interview.
Demographic data collected included sex, age, race, and education level. The race/ethnic groups identified in NHANES included non-Hispanic white, non-Hispanic black, Mexican American, and other. Education level was categorized as completion of less than high school, high school completion, or education after high school. NHANES participants showed containers of the dietary supple- ments, antacids, and prescription medications that contained nutrients to interviewers; the dietary supplement files contain these data. The interviewers asked about participant?s use of vitamins, minerals, herbs, and other supplements over the past 30 d and collected detailed infor- mation on type, consumption frequency, duration, and amount taken for each reported supplement.What they found:
In this nationally representative, prospective sample of adults who were without prevalent CVD, use of MVMs [MULTIVITAMIN-MINERALS] for >3 years was associated with reduced risk of CVD mortality at a median of 18 y of follow-up.Limitations: Only >40 years of age, only women
The Physicians' Health Study II - Multivitamins in the Prevention of Cancer in Men
- Published: 2012
- Time period: 1997-2011
- Participants:14 641 (non-cancer) + 1312 (cancer)
- Age: >50
- Inclusion criteria: male physicians
- Exclusion criteria: A 12-week placebo, run-in period excluded men who were nonadherent.
The PHS II was a randomized, double-blind, placebo-controlled, 2×2×2×2 factorial trial evaluating the balance of risks and benefits of a multivitaminHow they documented:
Participants were sent monthly calendar packs containing a multivitamin or placebo (taken daily) every 6 months for the first year, then annually thereafter.
We also sent participants annual questionnaires asking about adherence, adverse events, new end points, and risk factorsWhat they documented:
"Total cancer (excluding nonmelanoma skin cancer), with prostate, colorectal, and other site-specific cancers among the secondary end points."
What they found:
long-term daily multivitamin use had a modest but statistically significant reduction in the primary end point of total cancer after more than a decade of treatment and follow-up.Limitations: Only men, only >50y,
Studies with evidence against multivitamin health benefits
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
- Published: 2013 (META-ANALYSIS)
Two investigators independently reviewed each study's abstract against prespecified inclusion criteria. We included fair- and good-quality randomized, controlled trials that assessed the effectiveness or safety of supplements in the primary prevention of CVD, cancer, or all-cause mortality in the general adult population without a history of CVD or cancer. We included fair- and good-quality secondary prevention trials if they hypothesized effects on outcomes included in this review and not present at baseline in the study (for example, a trial of secondary skin cancer prevention that also reported on other cancers). We included only studies that were conducted among community-dwelling, nutrient-sufficient adults who had no chronic disease and were performed in countries with a Human Development Index of “very high” (11). We also required supplement doses to be lower than the upper tolerable limit set by the U.S. Food and Nutrition Board (12)What they documented:
We specifically sought studies of the following vitamins and minerals: vitamins A, B1, B2, B6, B12, C, D, and E; calcium; iron; zinc; magnesium; niacin; folic acid; ß-carotene; and selenium. We included studies that evaluated single, paired, and combinations of 3 or more vitamins and minerals; we use the term “multivitamin” to refer to those combinations.What they found:
We screened 12 766 abstracts, reviewed 277 full-text articles, and included 103 articles (26 studies) (Appendix Figure 2 of the Supplement). Four trials (19–22) and 1 cohort study (23) examined the benefits and harms of multivitamin supplementation (Supplement). Twenty-two trials and 2 cohort studies examined the benefits and harms of individual or paired supplements (Supplement): 6 studies of ß-carotene (24–29), 6 studies of vitamin E (22, 24, 30–33), 3 studies of selenium (33–35), 5 studies of vitamin A (23, 29, 36–38), 2 studies of vitamin C (30–31), 1 study of folic acid (39), 3 studies of vitamin D (40–42), 2 studies of vitamin D in combination with calcium (43–44), and 4 studies of calcium (40, 43, 45–46). The study sizes ranged from 128 to 72 337 individuals with average ages ranging from 22 to 77 years, although in most studies the mean age was older than 50 years (Supplement). Six studies were conducted among women only, 5 were conducted among men only, and the remaining studies were in mixed populations (24.2% to 84.7% women). The effects of the supplements were examined between 6 months and 16 years; most studies provided less than a decade of follow-up.
This review included 26 studies (24 randomized, controlled trials and 2 cohort studies) that examined the benefits and harms of using vitamin and mineral supplements for primary prevention of CVD, cancer, or all-cause mortality in healthy individuals without known nutritional deficiencies. We found no consistent evidence that the included supplements affected CVD, cancer, or all-cause mortality in healthy individuals without known nutritional deficiencies. Other systematic reviews have arrived at this same conclusion (56–66). The certainty of this result is tempered, however, because few fair- or good-quality studies are available for all supplements except vitamin E and ß-carotene. For vitamin E, we identified 6 fair- to good-quality trials that produced clearly null effects on these end points. This result is consistent with the conclusions of other systematic reviews and meta-analyses of vitamin E (67–71). Our review also confirmed the established harm of ß-carotene supplementation on lung cancer incidence and death for individuals at high risk for lung cancer (24, 29, 72). Further, we identified 6 trials that failed to detect any benefit from ß-carotene supplementation for any individuals.
Dietary Supplements and Mortality Rate in Older Women
- Published: 2011
- Time period: 1986-2008
- Participants: 38 772
- Age: Mean age: 61,6
- Inclusion criteria: Female
- Exclusion criteria: "[...] excluding from all analyses those who did not adequately complete a questionnaire including food frequency and supplement use at baseline in 1986"
Of these women, 99.2% were white and 98.6% were postmenopausal
How they documented:
Food intake was assessed at baseline and in the 2004 follow-up, using 2 nearly identical versions of the validated 127-food item Harvard Service Food Frequency Questionnaire.What they documented:
Supplement use was queried in 1986, 1997, and 2004 and included the 15 supplements assessed at all 3 surveys: multivitamins; vitamins A, beta-carotene, B6, folic acid, B complex, C, D, and E; and minerals iron, calcium, copper, magnesium, selenium, and zinc. Different forms of vitamin D, cholecalciferol (D3) or ergocalciferol (D2), were not distinguished. At the baseline and 2004 follow-up surveys, the supplement-related questions were part of the Food Frequency Questionnaire.
Mortality rates.
They excluded deaths that were "related to injury, accident, and suicide, because it is unlikely that supplement use would be causally related to these outcomes."
What they found:
[...] most of the supplements studied were not associated with a reduced total mortality rate in older women. In contrast, we found that several commonly used dietary vitamin and mineral supplements, including multivitamins, vitamins B6, and folic acid, as well as minerals iron, magnesium, zinc, and copper, were associated with a higher risk of total mortality. Of particular concern, supplemental iron was strongly and dose dependently associated with increased total mortality risk. Also, the association was consistent across shorter intervals, strengthened with multiple use reports and with increasing age at reported use. Supplemental calcium was consistently inversely related to total mortality rate; however, no clear dose-response relationship was observed.Limitations: Does not strictly deal with multivitamins, but still interesting
Also, supplement users were more likely to have lower intake of energy, total fat, and monounsaturated fatty acids, saturated fatty acids and to have higher intake of protein, carbohydrates, polyunsaturated fatty acids, alcohol, whole grain products, fruits, and vegetables.
Enough Is Enough: Stop Wasting Money on Vitamin and Mineral Supplements
- Published: 2013 (META-ANALYSIS)
What they found:
The large body of accumulated evidence has important public health and clinical implications. Evidence is sufficient to advise against routine supplementation, and we should translate null and negative findings into action. The message is simple: Most supplements do not prevent chronic disease or death, their use is not justified, and they should be avoided. This message is especially true for the general population with no clear evidence of micronutrient deficiencies, who represent most supplement users in the United States and in other countries (9).Limitations: Authors seem emotionally invested in the outcome of the debate. They may be picking studies that support their views.
In conclusion, ß-carotene, vitamin E, and possibly high doses of vitamin A supplements are harmful. Other antioxidants, folic acid and B vitamins, and multivitamin and mineral supplements are ineffective for preventing mortality or morbidity due to major chronic diseases. Although available evidence does not rule out small benefits or harms or large benefits or harms in a small subgroup of the population, we believe that the case is closed— supplementing the diet of well-nourished adults with (most) mineral or vitamin supplements has no clear benefit and might even be harmful. These vitamins should not be used for chronic disease prevention. Enough is enough.
Beta-carotene in multivitamins and the possible risk of lung cancer among smokers versus former smokers
Published: 2008 (META-ANALYSIS)
How they documented:
The authors systemically reviewed the published literature using a search of the MEDLINE database and performed a meta-analysis of large randomized trials that reported on the effect of beta-carotene supplementation on the incidence of lung cancer among smokers or former smokers. A sample of multivitamins was evaluated for their beta-carotene content and the suggested daily dosage.What they documented: Beta-carotene's possible interaction with lung cancer in smokers
What they found:
Four studies contributing 109,394 subjects were available for analysis. The average daily beta-carotene dosage in these trials ranged from 20 to 30 mg daily. Among current smokers, beta-carotene supplementation was found to be significantly associated with an increased risk of lung cancer (odds ratio [OR], 1.24; 95% confidence interval [95% CI], 1.10–1.39). Among former smokers, there was no significant increase noted (OR, 1.10; 95% CI, 0.84–1.45). In a sample of 47 common multivitamins, beta-carotene was present in 70% of the identified formulas. The median dosage of beta-carotene was 0.3 mg (range, 0–17.2 mg) daily. The beta-carotene content was found to be significantly higher among multivitamins sold to improve visual health than among other multivitamins, with a median daily dosage of 3 mg (range, 0–24 mg).
Studies with mixed findings or no effect
Vitamin/mineral supplementation and cancer, cardiovascular, and all-cause mortality in a German prospective cohort
- Published: 2012
- Time period: 1994-2006 (11 year average followup)
- Participants: 23 943
- Age: 35-64
- Inclusion criteria: male and female
- Exclusion criteria: cancer, myocardial infarction/stroke
In the EPIC-Heidelberg cohort, vitamin/mineral supplementation was assessed at different time points. In a baseline face-to-face interview, regular use of vitamin/mineral supplements was assessed by asking participants the following question: ‘‘Did you regularly take any medications or vitamin/mineral supplements in the last 4 weeks?’’What they documented:
In a baseline self-administered food frequency questionnaire (FFQ), participants were also asked whether they had taken vitamin/mineral supplements for C 4 weeks in the last 12 months.
Intakes of 148 food and beverage items in the last 12 months before recruitment were measured using the baseline FFQ, which had been validated by twelve 24-h dietary recalls [ 8 , 9 ]. Baseline demographic, lifestyle, and other health-related characteristics were measured in a baseline lifestyle questionnaire survey and a baseline physical examination.
Cancer, cardiovascular, and all-cause mortality.
What they found:
After an 11-year follow-up of the EPIC-Heidelberg cohort, regularly taking any vitamin/mineral supplements was not statistically significantly associated with cancer, CVD, or all-cause mortality. However, antioxidant vitamin supplementation was significantly inversely associated with cancer mortality and all-cause mortality. In comparison with never users, baseline non-users who started taking vitamin/mineral supplements during follow- up had significantly increased risks of cancer mortality and all-cause mortality.
Multivitamin Use and Mortality in a Large Prospective Study
!!Important study!!
- Published: 1999
- Time period: 1982-1989
- Participants: 1,063,023 (!!!!!!)
- Age: >30 (!!!!!!!)
- Inclusion criteria: 30 or older
- Exclusion criteria:
Cancer Prevention Study II (CPS-II) is a nationwide, prospective mortality study of nearly 1.2 million US men and women aged 30 years and older that began in 1982. At the request of an American Cancer Society volunteer, each enrollee completed a four-page mailed questionnaire in 1982 that requested information on history of cancer and other diseases, use of medicines and vitamins, use of alcohol and tobacco, diet, as well as other factors potentially affecting mortality. This analysis includes 1,063,023 people (453,962 men; 609,061 women) who, at enrollment, reported usable data on vitamin use.How they documented:
[...] each enrollee completed a four-page mailed questionnaire in 1982 that requested information on history of cancer and other diseases, use of medicines and vitamins, use of alcohol and tobacco, diet, as well as other factors potentially affecting mortality.
What they documented:
[...] we classified deaths due to ischemic heart disease (ICD-9 codes 410–414), cerebrovascular disease (stroke) (ICD-9 codes 430–438), and all cancers combined, except nonmelanoma skin cancer (ICD-9 codes 140–195 and 199–209). We examined separately the three most common causes of cancer mortality: lung (ICD-9 code 162), colo-rectal (ICD-9 codes 153–154), and (for men) prostate (ICD-9 code 185) and (for women) breast (ICD-9 code 174), and all other cancers combined. All-cause mortality included persons who died of any cause.What they found:
This large prospective study provides limited support for the hypothesis that multivitamin supplements may reduce death rates from ischemic heart disease in the general population. Men and women who took a multivitamin without other supplements had lower death rates from ischemic heart disease than did those who took no multivitamins. However, the association was attenuated when analyses were adjusted for additional cardiovascular risk factors besides age, and no consistent gradient of decreasing risk was seen with either the frequency or the duration of multivitamin use.
Men and women who used both multivitamins and vitamin A, C, or E had lower risks of dying from heart disease and stroke than did nonusers than one might expect from the relative risks for users of either only a multivitamin or only a vitamin A, C, or E supplement.
Multivitamin use and the risk of mortality and cancer incidence: the multiethnic cohort study
- Published: 2011
- Time period: 1993-2005 (11 year average follow-up)
- Participants: 182 099
- Age: 45-75
- Inclusion criteria: Living in Hawaii and California, ethnic group
- Exclusion criteria: "we excluded participants who were not in one of the targeted 5 ethnic groups (n = 13,991) or who reported invalid dietary intakes based on total energy intake or its components (n = 8,264) (12). We also excluded those with missing information on multivitamin use (n = 4,451) or smoking (n = 7,013)"
The baseline questionnaire included questions about the use of multivitamins (with/without minerals) and 7 single vitamin/mineral supplements. Subjects were asked to indicate whether they had used any of these supplements at least weekly during the previous year.What they documented:
In a follow-up questionnaire approximately 5 years after baseline (1999–2003), participants were asked the same question on multivitamin use but without duration of use.
During an average 11 years of follow-up, we identified 28,851 deaths (15,962 men and 12,889 women). Death from all causes was the primary endpoint in the analyses. In addition, according to the International Classification of Diseases, Ninth Revision (ICD-9) and Tenth Revision (ICD-10), we categorized the primary cause of death into cardiovascular diseases (ICD-9 codes 390–434, 436–448; ICD-10 codes I00–I78), cancer (ICD-9 codes 140–208; ICD-10 codes C00–C97), and all other causes.What they found:
In this large multiethnic cohort, we found no associations between multivitamin use and mortality from all causes, cardiovascular diseases, or cancer. The findings did not vary across subgroups by ethnicity, age, body mass index, preexisting illness, single vitamin/mineral supplement use, hormone replacement therapy use, and smoking status. In addition, there was no evidence indicating that multivitamin use increased or decreased risk for cancer, overall or at major sites, such as lung, colorectum, prostate, and breast.Limitations:
Multivitamin users are generally more health conscious than are nonusers (1, 36), which could confound the relation of multivitamin use with morbidity or mortality. Although we adjusted for well-known potential confounders including health-related behaviors such as smoking status, alcohol consumption, and physical activity (37), there may still be uncontrolled bias. In particular, we were unable to adjust for changes in potential confounders over time. The longest duration category for multivitamin use in our baseline questionnaire was 5 years and longer, although the effects of multivitamins on longevity and disease might take a longer period.The efficacy and safety of multivitamin and mineral supplement use to prevent cancer and chronic disease in adults: a systematic review for a National Institutes of Health state-of-the-science conference.
- Published: 2006 (META-ANALYSIS)
How they documented:
MEDLINE, EMBASE and the Cochrane Library were searched from 1966 to February 2006. References of articles were checked, experts were contacted, and tables of contents for 15 relevant journals were searched from January 2005 to February 2006. Search terms were reported in the full report (see Other Publications of Related Interest). Only studies reported in English were eligible for inclusion.What they documented:
Randomised controlled trials (RCTs) which assessed the efficacy of a multivitamin/mineral supplement for the prevention of one or more of the following chronic diseases were eligible for inclusion: cancer; myocardial infarction or stroke; type 2 diabetes; Parkinson's disease or dementia; cataracts; macular degeneration or hearing loss; osteoporosis; osteopenia; rheumatoid arthritis; osteoarthritis; non-alcoholic steatorrheic hepatitis; non-alcoholic fatty liver disease; chronic renal insufficiency; chronic nephrolithiasis; HIV (human immunodeficiency virus) infection; hepatitis C; tuberculosis; and chronic obstructive pulmonary disease. Studies which included only the following types of participants were excluded from the review: pregnant women; people aged up to 18 years; people with a chronic disease or those receiving treatment for such a disease; patients in long-term care facilities; or people with a clinical nutritional deficiency. Studies which assessed only safety or which did not assess supplement use separately from dietary intake were also excluded. For the assessment of safety observational studies in adults and children were also eligible for inclusion.
To assess the efficacy and safety of multivitamin and mineral supplements for the primary prevention of cancer and chronic disease in the general population.What they found:
There was insufficient evidence to determine the presence or absence of benefits from the use of multivitamin and mineral supplements for the prevention of cancer and chronic disease.
Antioxidant vitamin and mineral supplements for slowing the progression of age-related macular degeneration
- Published: 2012 (META-ANALYSIS)
The objective of this review was to assess the effects of antioxidant vitamin or mineral supplementation, alone or in combination, on the progression of AMD.
What they found:
People with AMD may experience delay in progression of the disease with antioxidant vitamin and mineral supplementation. This finding is drawn from one large trial conducted in a relatively well-nourished American population. The generalisability of these findings to other populations is not known. Although generally regarded as safe, vitamin supplements may have harmful effects. A systematic review of the evidence on harms of vitamin supplements is needed.
Vitamin, Mineral, and Multivitamin Supplements for the Primary Prevention of Cardiovascular Disease and Cancer: U.S. Preventive Services Task Force Recommendation Statement
- Published: 2014 (META-ANALYSIS)
How they documented:
In order to update its 2003 recommendation, the USPSTF reviewed evidence of the efficacy of multivitamin or mineral supplements in the general adult population for the prevention of cardiovascular disease and cancer (3, 12). The value of vitamins that naturally occur in food and the use of vitamin supplements for the prevention of other conditions (for example, neural tube defects) and for the secondary prevention of complications in patients with existing disease are outside the scope of this review.What they documented:
This recommendation applies to healthy adults without special nutritional needs (typically aged 50 years or older). It does not apply to children, women who are pregnant or may become pregnant, or persons who are chronically ill or hospitalized or have a known nutritional deficiency.What they found:
The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of multivitamins for the prevention of cardiovascular disease or cancer. (I statement)The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of single- or paired-nutrient supplements (except ß-carotene and vitamin E) for the prevention of cardiovascular disease or cancer. (I statement)The USPSTF recommends against ß-carotene or vitamin E supplements for the prevention of cardiovascular disease or cancer. (D recommendation)Limitations:
Recommendations made by the USPSTF are independent of the U.S. government. They should not be construed as an official position of the Agency for Healthcare Research and Quality or the U.S. Department of Health and Human Services.
Long-Term Multivitamin Supplementation and Cognitive Function in Men
- Published: 2013
- Time period: 1997-2011
- Participants: 5947
- Age: >65
- Inclusion criteria: male physician
- Exclusion criteria:
Up to 4 repeated cognitive assessments by telephone interview were completed over 12 yearsWhat they documented:
To evaluate whether long-term multivitamin supplementation affects cognitive health in later life.What they found:
In male physicians aged 65 years or older, long-term use of a daily multivitamin did not provide cognitive benefits.Limitations:
Doses of vitamins may be too low or the population may be too well-nourished to benefit from a multivitamin.
Other studies
- http://jnci.oxfordjournals.org/content/85/18/1483
- http://ac.els-cdn.com/S0197245698000154/1-s2.0-S0197245698000154-main.pdf?_tid=9c979a66-8b94-11e5-b703-00000aacb360&acdnat=1447590790_d27cad7de21e7c0af9074537f10067e0
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