MD, PhD, FMedSci, FSB, FRCP, FRCPEd

antioxidants

While my last post was about the risk following some naturopaths’ advice, this one is about the effectiveness of naturopathic treatments. This is a complex subject, not least because naturopaths use a wide range of therapies (as the name implies, they pride themselves of employing all therapeutic means supplied by nature). Some of these interventions are clearly supported by good evidence; for instance, nobody would doubt the effectiveness of a healthy diet or the benefits of regular exercise. But what about all the other treatments naturopaths use? The best approach to find an answer might be to assess not each single therapy but to evaluate the entire package of the naturopathic approach, and not a single study but all such trials.

This is precisely what US researchers have recently done. The purpose of this interesting, new systematic review was to compile and consolidate research that has investigated the whole practice of naturopathic medicine as it is practiced in community settings in order to better assess the quantity and quality of the research, and clinical effect, if any.

In order to get included into the review, studies had to report results from multi-modal treatment delivered by North American naturopathic doctors. The effect size for each study was calculated; no meta-analysis was undertaken.

Fifteen studies met the authors’ inclusion criteria. They covered a wide range of chronic diseases. Most studies had low to medium risks of bias including acknowledged limitations of pragmatic trials. Effect sizes for the primary medical outcomes varied and were statistically significant in 10 out of 13 studies. A quality of life metric was included in all of the RCTs with medium effect size and statistical significance in some subscales.

The authors concluded that previous reports about the lack of evidence or benefit of naturopathic medicine (NM) are inaccurate; a small but compelling body of research exists. Further investigation is warranted into the effectiveness of whole practice NM across a range of health conditions.

This sounds like good news for naturopathy! However, there are several important caveats:

  • the authors seem to have only looked at US studies (naturopathy is a European tradition!),
  • the searches were done three years ago, and more recent data were thus omitted,
  • the authors included all sorts of investigations, even uncontrolled studies; only 6 were RCTs,
  • rigorous trials were very scarce; and for each condition, they were even more so,
  • the authors mention the PRISMA guidelines for systematic reviews implying that they followed them but, in fact, they did not.

My biggest concern, however, is something else. It relates to the interventions tested in these studies. The authors claim that their results table provides full details on this issue but this is unfortunately not true. All we have by way of an explanation is the authors’ remark that the interventions tested in the studies of their review included diet counseling and nutritional recommendations, specific home exercises and physical activity recommendations, deep breathing techniques or other stress reduction strategies, dietary supplements including vitamins, hydrotherapy, soft-tissue manual techniques, electrical muscle stimulation, and botanical medicines.

Survey data from two US states tell us that the most commonly prescribed naturopathic therapeutics are botanical medicines (51% of visits in Connecticut, 43% in Washington), vitamins (41% and 43%), minerals (35% and 39%), homeopathy (29% and 19%) and allergy treatments (11% and 13%). They also inform us that the mean length of a consultation with an US naturopath is about 40 minutes.

I think, this puts things into perspective. If I advise a patient with diabetes or hypertension or coronary heat disease to follow an appropriate diet, exercise and to adhere to some stress reduction program, if in addition I show empathy and compassion during a 40 minute consultation and make sure that my advise is taken seriously and subsequently adhered to, the outcome is likely to be positive. Naturopaths may elect to call this package of intervention ‘naturopathy’, however, I would call it good conventional medicine.

The problem, I think is clear: good therapeutic advice is effective but it is not naturopathy, and it cannot be used to justify the use of doubtful interventions like homeopathy or all sorts of dodgy supplements. Testing whole treatment packages of this nature can therefore lead to highly misleading results, particularly if the researchers draw unwarranted conclusions about specific schools of health care.

Multivitamins are widely used, mainly for disease prevention, and particularly cardiovascular disease (CVD). But there are only few prospective studies investigating their association with both long- and short-term risk. In view of these facts, new evidence is more than welcome.

The objective of this study was to investigate how multivitamin use is associated with the long- and short-term risk of CVD. A prospective cohort study was conducted of 37,193 women from the Women’s Health Study aged ≥45 y and free of CVD and cancer at baseline who were followed for an average of 16.2 y. At baseline, women self-reported a wide range of lifestyle, clinical, and dietary factors. Women were categorized into 1) no current use and 2) current use of multivitamins. Duration and updated measures over the course of the follow-up to address short-term effects were also considered. Women were followed for major CVD events, including myocardial infarction (MI), stroke, and CVD death.

During the follow-up, 1493 incident cases of CVD [defined as myocardial infarction (MI), stroke, and CVD death] occurred. In multivariable analyses, multivitamin use compared with no use was not associated with major CVD event, stroke, or CVD death. A non-significant inverse association was observed between baseline multivitamin use and major CVD events among women aged ≥70 y (P-interaction = 0.04) and those consuming <3 servings/d of fruit and vegetables (P-interaction = 0.01). When updating information on multivitamin use during the course of follow-up, no associations were observed for major CVD events, MI, stroke, and CVD death.

The authors concluded that, in this study of middle-aged and elderly women, neither baseline nor time-varying multivitamin use was associated with the long-term risk of major CVD events, MI, stroke, cardiac revascularizations, or CVD death. Additional studies are needed to clarify the role of multivitamins on CVD.

Even the most enthusiastic vitamin fan will find it hard to argue with these findings; they seem rock solid. Vitamins have their name from the fact that they are vital for our survival – we all need them. But, in developed countries, we all get them through our daily food. Any excess of water-soluble vitamins is swiftly excreted via the urine. Any excess of fat-soluble vitamins is stored in the body and may, in some cases, even represent a health risk.

Exceptions are vulnerable groups such as children, the elderly, pregnant women and patients with certain diseases. These individuals can suffer from hypovitaminoses, the only reason for regularly using vitamin supplements. But for the vast majority of the population, the only effects of regular vitamin supplementation are that we enrich the manufacturers and render our urine expensive.

Dietary supplements (DS) are heavily promoted usually with the claim that they have stood the test of time and that they are natural and hence harmless. Unsurprisingly, their use has become very wide-spread. A new study determined the use of DSs, factors associated with DS use, and reasons for use among U.S. college students.

College students (N = 1248) at 5 U.S. universities were surveyed. Survey questions included descriptive demographics, types and frequency of DS used, reasons for use and money spent on supplements. Supplements were classified using standard criteria. Logistic regression analyses examined relationships between demographic and lifestyle factors and DS use.

Sixty-six percent of college students surveyed used DS at least once a week, and 12% consumed 5 or more supplements a week. Forty-two percent used multivitamins/multiminerals, 18% vitamin C, 17% protein/amino acids and 13% calcium at least once a week. Factors associated with supplement use included dietary patterns, exercise, and tobacco use. Students used supplements to promote general health (73%), provide more energy (29%), increase muscle strength (20%), and enhance performance (19%).

The authors of this survey concluded that college students appear more likely to use DS than the general population and many use multiple types of supplements weekly. Habits established at a young age persist throughout life. Therefore, longitudinal research should be conducted to determine whether patterns of DS use established early in adulthood are maintained throughout life. Adequate scientific justification for widespread use of DS in healthy, young populations is lacking.

Another new study investigated the use of DSs in 334 dancers from 53 countries, who completed a digitally based 35-question survey detailing demographic information and the use of DSs. Supplement use was prevalent amongst this international cohort, with 48% reporting regular DSs use. Major motives for supplement use were to improve health, boost immunity, and reduce fatigue. Forty-five percent believed that dancing increased the need for supplementation, whilst 30% recognized that there were risks associated with DSs.

The most frequently consumed DSs were vitamin C (60%), multivitamins (67%), and caffeine (72%). A smaller group of participants declared the use of whey protein (21%) or creatine (14%). Supplements were mainly obtained from pharmacies, supermarkets, and health-food stores. Dancers recognized their lack of knowledge in DSs use and relied on peer recommendations instead of sound evidence-based advice from acknowledged nutrition or health care professionals.

The authors concluded that this study demonstrates that DSs use is internationally prevalent amongst dancers. Continued efforts are warranted with regard to information dissemination.

Finally, a third study investigated use of DSs in patients in Japan. This survey was completed by 2732 people, including 599 admitted patients, 1154 ambulatory patients, and 979 healthy subjects who attended a seminar about DSs. At the time of the questionnaire, 20.4% of admitted patients, 39.1% of ambulatory patients, and 30.7% of healthy subjects were using DSs, which including vitamin/mineral supplements, herbal extracts, its ingredients, or food for specified health uses.

The primary purpose for use in all groups was health maintenance, whereas 3.7% of healthy subjects, 10.0% of ambulatory patients, and 13.2% of admitted patients used DSs to treat diseases. In addition, 17.7% of admitted patients and 36.8% of ambulatory patients were using DSs concomitantly with their medications. However, among both admitted patients and ambulatory patients, almost 70% did not mention DSs use to their physicians. Overall, 3.3% of all subjects realized adverse effects associated with DSs.

The authors concluded that communication between patients and physicians is important to avoid health problems associated with the use of DSs.

There is little doubt, DSs are popular with all sorts of populations and have grown into a multi billion dollar industry. There is also no doubt that the use of only very few DSs are evidence-based (and if so, in only relatively rare situations). And there can be no doubt that many DSs can do harm. What follows is simple: for the vast majority of DSs the benefits do not demonstrably out-weigh the risks.

If that is true, we have to ask ourselves: Why are they so popular?

The answer, I think, is because of the very phenomenon I am constantly trying to fight on this blog – IRRESPONSIBLE CHARLATANS PULLING WOOL OVER CONSUMERS EYES.

Many dietary supplements are heavily promoted for the prevention of chronic diseases, including cardiovascular disease (CVD) and cancer. But do they actually work or are they just raising false hopes? The evidence on this subject is confusing and proponents of both camps produce data which seemingly support their claims. In this situation, we need an independent analysis of the totality of the evidence to guide us. And one such review has just become available

The purpose of this article was to systematically review evidence for the use of multivitamins or single nutrients and functionally related nutrient pairs for the primary prevention of CVD and cancer in the general population.

The authors searched 5 databases to identify literature that was published between 2005 and January 29, 2013. They also examined the references from the previous reviews and other relevant articles to identify additional studies. In addition, they searched Web sites of government agencies and other organizations for grey literature. Two investigators independently reviewed identified abstracts and full-text articles against a set of a priori inclusion and quality criteria. One investigator abstracted data into an evidence table and a second investigator checked these data. The researchers then qualitatively and quantitatively synthesized the results for 4 key questions and grouped the included studies by study supplement. Finally, they conducted meta-analyses using Mantel-Haenzel fixed effects models for overall cancer incidence, CVD incidence, and all-cause mortality.

103 articles representing 26 unique studies met the inclusion criteria. Very few studies examined the use of multivitamin supplements. Two trials showed a protective effect against cancer in men; only one of these trials included women and found no effect. No effects of treatment were seen on CVD or all-cause mortality.

Beta-carotene showed a negative effect on lung cancer incidence and mortality among individuals at high risk for lung cancer at baseline (i.e., smokers and asbestos-exposed workers); this effect was persistent even when combined with vitamin A or E. Trials of vitamin E supplementation showed mixed results and altogether had no overall effect on cancer, CVD, or all-cause mortality. Only one of two studies included selenium trials showed a beneficial effect for colorectal and prostate cancer; however, this trial had a small sample size. The few studies addressing folic acid, vitamin C, and vitamin A showed no effect on CVD, cancer, and mortality. Vitamin D and/or calcium supplementation also showed no overall effect on CVD, cancer, and mortality. Harms were infrequently reported and aside from limited paradoxical effects for some supplements, were not considered serious.

The authors’ conclusion are less than encouraging: there are a limited number of trials examining the effects of dietary supplements on the primary prevention of CVD and cancer; the majority showed no effect in healthy populations. Clinical heterogeneity of included studies limits generalizability of results to the general primary care population. Results from trials in at-risk populations discourage additional studies for particular supplements (e.g., beta-carotene); however, future research in general primary care populations and on other supplements is required to address research gaps.

A brand-new RCT provides further information, specifically on the question whether oral multivitamins are effective for the secondary prevention of cardiovascular events. In total, 1708 patients aged 50 years or older who had myocardial infarction (MI) at least 6 weeks earlier with elevated serum creatinine levels were randomly assigned to an oral, 28-component, high-dose multivitamin and multi-mineral mixture or placebo. The primary end point was time to death, recurrent MI, stroke, coronary revascularization, or hospitalization for angina. Median follow-up was 55 months. Patients received treatments for a median of 31 months in the vitamin group and 35 months in the placebo group. 76% and 76% patients in the vitamin and placebo groups completed at least 1 year of oral therapy, and 47% and 50% patients completed at least 3 years. Totals of 46% and 46% patients in both groups discontinued the vitamin regimen, and 17% of patients withdrew from the study.

The primary end point occurred in 27% patients in the vitamin group and 30% in the placebo group. No evidence suggested harm from vitamin therapy in any category of adverse events. The authors of this RCT concluded that high-dose oral multivitamins and multiminerals did not statistically significantly reduce cardiovascular events in patients after MI who received standard medications. However, this conclusion is tempered by the nonadherence rate.

These findings are sobering and in stark contrast to what the multi-billion dollar supplement industry promotes. The misinformation in this area is monumental. Here is what one site advertises for heart disease:

Vitamin C could be helpful, limit dosage to 100 to 500 mg a day.

Vitamin E works better with CoQ10 to reduce inflammation in heart disease. Limit vitamin E to maximum 30 to 200 units a few times a week. Use a natural vitamin E complex rather than synthetic products.

CoQ10 may be helpful in heart disease, especially in combination with vitamin E. I would recommend limiting the dosage of Coenzyme Q10 to 30 mg daily or 50 mg three or four times a week.

B complex vitamins reduce levels of homocysteine. Keep the vitamin B dosages low, perhaps one or two times the RDA. Taking higher amounts may not necessary be a healthier approach.

Curcumin protects rat heart tissue against damage from low oxygen supply, and the protective effect could be attributed to its antioxidant properties. Curcumin is derived from turmeric, which is often used in curries.

Garlic could be an effective treatment for lowering cholesterol and triglyceride levels for patients with a history or risk of cardiovascular disease, especially as a long term strategy.

Terminalia arjuna, an Indian medicinal plant, has been reported to have beneficial effects in patients with ischemic heart disease in a number of small studies. Arjuna has been tested in angina and could help reduce chest pain.
Magnesium is a mineral that could help some individuals. It is reasonable to encourage diets high in magnesium as a potential means to lower the risk of coronary heart disease.

Danshen used in China for heart conditions.

And in the area of cancer, the choice is even more wide and audacious as this web-site for example demonstrates.

So, the picture that emerges from all this seems fairly clear. Despite thousands of claims to the contrary, dietary supplements are useless in preventing cardiovascular diseases or cancer. All they do produce, I am afraid, is rather expensive urine.

In 1747, James Lind conducted what may well be the first documented controlled clinical trial in the history of medicine. He treated a small group of healthy sailors with a range of different remedies to see whether one of these regimen might be effective in preventing scurvy. The results showed that lemon and lime juice – effectively vitamin C – did the trick. This trial changed the world: it saved tens of thousands of lives, gave Britain the advantage at sea needed to become a dominant empire, and set medicine on the track to eventually become evidence-based.

Of course, Lind did not know that the effective principle in his lemon/lime juice was vitamin C. The Hungarian physiologist Albert Szent-Gyorgyi discovered vitamin C only ~200 years later and received the Nobel Prize for it in 1937. Since then, research has been buoyant, and vitamin C has been advocated for almost every condition one can think of. Looking at some of the claims made for it, I get the impression that more charlatans have jumped on the vitamin C band-waggon than the old vehicle can support. In alternative medicine, high-dose IV vitamin C is a popular variation of Lind’s concept, not least for the treatment of cancer.

Researchers from the NIH in the US surveyed attendees at annual CAM Conferences in 2006 and 2008, and determined sales of intravenous vitamin C by major U.S. manufacturers/distributors. They also queried practitioners for adverse effects, compiled published cases, and analyzed FDA’s Adverse Events Database. Of 199 survey respondents (out of 550), 172 practitioners had administered IV vitamin C to 11,233 patients in 2006 and to 8876 patients in 2008. The average dose was 28 grams every 4 days, with a mean of 22 treatments per patient. Estimated yearly doses used (as 25g/50ml vials) were 318,539 in 2006 and 354,647 in 2008. Manufacturers’ yearly sales were 750,000 and 855,000 vials, respectively. Common reasons for treatment included infection, cancer, and fatigue. Of 9,328 patients for whom data was available, 101 had adverse effects, mostly minor, including lethargy/fatigue in 59 patients, change in mental status in 21 patients and vein irritation/phlebitis in 6 patients. Publications documented serious adverse events, including two deaths. The FDA Adverse Events Database was uninformative.

The authors of this paper conclude that high dose IV vitamin C is in unexpectedly wide use by CAM practitioners. Other than the known complications of IV vitamin C in those with renal impairment or glucose 6 phosphate dehydrogenase deficiency, high dose intravenous vitamin C appears to be remarkably safe. Physicians should inquire about IV vitamin C use in patients with cancer, chronic, untreatable, or intractable conditions and be observant of unexpected harm, drug interactions, or benefit.

I find these results somewhat worrying. Desperate cancer patients are constantly being told that they can fight the disease with high-dose vitamin C, for instance on the >9 million (!) websites on this subject. One site, for instance, leaves little doubt about the efficacy of vitamin C as a treatment for cancer: First shown to be a powerful anti-cancer agent in 1971, it wasn’t until 20 years later that vitamin C started to be accepted by the mainstream medical profession. Eating a vitamin C-rich diet substantially reduces the risk of cancer, and high intakes – above 5000mg a day (the equivalent of 100 oranges) – substantially increases the life expectancy of cancer patients.

Statements like this one give false hope to cancer patients which is unethical and cruel and might hasten the death of many. The reality is quite different and provides little reason for such hope. Here are just a few conclusions from recent scientific analyses on this or closely related topics:

post-diagnosis vitamin C supplementation at the level observed in our population was not associated with survival

Evidence is insufficient to prove the presence or absence of benefits from use of multivitamin and mineral supplements to prevent cancer and chronic disease

We could not find evidence that antioxidant supplements prevent gastrointestinal cancers. On the contrary, they seem to increase overall mortality. The potential cancer preventive effect of selenium should be studied in adequately conducted randomised trial

The question whether the regular intake of high doses of vitamin C have a preventative effect for certain cancers is currently open. But there is no good reason to suggest that high dose IV vitamin C is an effective treatment for any cancer. To pretend otherwise, as so many alternative practitioners seem to do, is less than responsible – in fact, it is a hallmark for cancer quackery.

Antioxidant vitamins include vitamin E, beta-carotene, and vitamin C. They are often recommended and widely used for preventing major cardiovascular outcomes. However, the effect of antioxidant vitamins on cardiovascular events remains unclear. There is plenty of evidence but the trouble is that it is not always of high quality and confusingly contradictory. Consequently, it is possible to cherry-pick the studies you prefer in order to come up with the answer you like. That this approach is counter-productive should be obvious to every reader of this blog. Only a rigorous systematic review can provide an answer that is as reliable as possible with the data available to date. Chinese researchers have just published such an assessment.

They searched PubMed, EmBase, the Cochrane Central Register of Controlled Trials, and the proceedings of major conferences for relevant investigations. To be eligible, studies had to be randomized, placebo-controlled trials reporting on the effects of antioxidant vitamins on cardiovascular outcomes. The primary outcome measures were major cardiovascular events, myocardial infarction, stroke, cardiac death, total death, and any adverse events.

The searches identified 293 articles of which 15 RCTs reporting data on 188209 participants met the inclusion criteria. In total, these studies reported 12749 major cardiovascular events, 6699 myocardial infarction, 3749 strokes, 14122 total death, and 5980 cardiac deaths. Overall, antioxidant vitamin supplementation, as compared to placebo, had no effect on major cardiovascular events (RR, 1.00; 95% CI, 0.96-1.03), myocardial infarction (RR, 0.98; 95% CI, 0.92-1.04), stroke (RR, 0.99; 95% CI, 0.93-1.05), total death (RR, 1.03; 95% CI, 0.98-1.07), cardiac death (RR, 1.02; 95% CI, 0.97-1.07), revascularization (RR, 1.00; 95% CI, 0.95-1.05), total CHD (RR, 0.96; 95% CI, 0.87-1.05), angina (RR, 0.98; 95% CI, 0.90-1.07), and congestive heart failure (RR, 1.07; 95% CI, 0.96 to 1.19).

The authors’ conclusion from these data could not be clearer: Antioxidant vitamin supplementation has no effect on the incidence of major cardiovascular events, myocardial infarction, stroke, total death, and cardiac death.

Few subjects in the realm of nutrition have attracted as much research during recent years as did antioxidants, and it is hard to think of a disease for which they are not recommended by this expert or another. Cardiovascular disease used to be the flag ship in this fleet of conditions; not so long ago, even the conventional medical wisdom sympathized with the notion that the regular supplementation of our diet with antioxidant vitamins might reduce the risk of cardiovascular disease and mortality.

Today, the pendulum has swung back, and it now seems to be mostly the alternative scene that still swears by antioxidants for that purpose. Nobody doubts that antioxidants have important biological functions, but this excellent meta-analysis quite clearly and fairly convincingly shows that buying antioxidant supplements is a waste of money. It does not promote cardiovascular health, it merely generates very expensive urine.

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