Jul 09 2019

More Bad News For Vitamin Pushers

Vitamins are, by actual definition, essential nutrients for humans. They are substances we need but cannot make ourselves from other nutrients, and therefore must consume. Each of the vitamins have a disease resulting from a deficiency of that vitamin. For some there may also be negative health effects from having an insufficiency (less than optimal levels, but not low enough to cause a deficiency state). This is why you should eat your vegetables, and have an overall well-rounded diet – to make sure you get enough of all the vitamins and other needed nutrients.

But of course if there is a way to exploit a fact to make money, someone will do it. In this case an entire industry has emerged to make money by convincing the public they need to take vitamin pills, the more the better. In 2017 the supplement industry in the US reached $36.1 billion a year. Unfortunately, the path to better health is not so simple, and the science simply does not support the vitamin industry hype.

Yet another meta-analysis was just published again demonstrating that routine supplementation is mostly worthless, and may even be harmful. This one is focusing on vascular outcomes, but since heart disease is the #1 killer, and stroke the #3 killer, vascular risk has a major impact on life expectancy. In 2018 I wrote about a meta-analysis published in the Journal of the American College of Cardiology. This study found:

  • Multivitamins, vitamins D, C, A, B6, E, calcium, β-carotene, zinc, iron, magnesium, and selenium had no benefit or harm for vascular disease or all-cause mortality.
  • Folic acid and B-complex (Folic acid, B6 and B12) reduced stroke risk
  • Antioxidants and niacin increased all-cause mortality.

The reduced stroke risk from folic acid, however, was largely due to a Chinese study. In many parts of China they do not routinely fortify food with folate, and there is a significant risk of deficiency. These results may not translate, therefore, to Western countries with a different diet and with routine fortification to shore up deficiencies in our standard diet.

The new study looks at:

Nine systematic reviews and 4 new RCTs were selected that encompassed a total of 277 trials, 24 interventions, and 992 129 participants. A total of 105 meta-analyses were generated.

They found:

  • reduced salt intake decreased the risk for all-cause mortality in normotensive participants and cardiovascular mortality in hypertensive participants (moderate evidence)
  • omega-3 long-chain polyunsaturated fatty acid (LC-PUFA) was associated with reduced risk for myocardial infarction (low certainty evidence)
  • Folic acid was associated with lower risk for stroke (low certainty)
  • calcium plus vitamin D increased the risk for stroke (moderate certainty).
  • Other nutritional supplements, such as vitamin B6, vitamin A, multivitamins, antioxidants, and iron and dietary interventions, such as reduced fat intake, had no significant effect on mortality or cardiovascular disease outcomes (very low– to moderate-certainty evidence).

These results are similar to the 2018 meta-analysis, with some difference. Both studies found that most vitamins had no effect of vascular disease or mortality, and some evidence that folic acid may reduce stroke risk. This study also looked at salt and omega-3, not mentioned in the previous study. The 2018 study found a possible increased risk of vascular disease from antioxidants, while the 2019 study found no effect, good or bad. Finally, the 2019 study also found an increased stroke risk from taking calcium and vitamin D.

That there is some benefit to moderating salt intake is already known, although the extent of this effect is still debated. The benefits of omega-3 remain controversial. A 2018 Cochrane systematic review essentially found no benefit to omega-3 supplementation, also concluding:

There is evidence that taking omega-3 capsules does not reduce heart disease, stroke or death. There is little evidence of effects of eating fish. Although EPA and DHA reduce triglycerides, supplementary omega-3 fats are probably not useful for preventing or treating heart and circulatory diseases. However, increasing plant-based ALA may be slightly protective for some heart and circulatory diseases.

So eat more plants, something that is already fairly well established. Another 2019 study funded by the NIH and published earlier this year also essentially found no benefit, and some risks, to routine supplementation. They also found that: “People who took more than 1,000 milligrams of supplemental calcium per day were more likely to die of cancer than those who didn’t.”

The folic acid benefit remains uncertain. The current study gave the data a low certainty, and the contamination of data from China remains an issue. If we are being generous we might say that all of the health effects of all routine supplementation combined is probably close to a wash. That’s a lot of nothing for a 36 billion dollar a year industry.

Part of the problem is that the logic of routine (note I keep using the word “routine”) is questionable. There is no argument that vitamins are useful, even essential, in treating deficiencies, and managing risk in special situations resulting from increased need to decreased access. Where there is evidence for widespread nutrient insufficiency due to a typical diet, the solution is fortification. We fortify milk with calcium, salt with iodine, and bread with folic acid. Alcoholics tend to be deficient in thiamine, and so fortifying wine with the vitamin makes sense.

There are also targeted populations who can statistically benefit from routine supplementation – pregnant women, those recovering from surgery or a severe injury, and those with malabsorption syndrome, perhaps resulting from gastric surgery. The third situation in which supplementation makes sense is in those with a documented deficiency or insufficiency. If you are low in B12 as measured in the blood, then taking extra B12 to correct the deficiency is evidence-based, and can have significant health benefits.

So supplementation makes sense to shore up deficiencies in the food supply, in targeted populations, and to treat documented deficiency. But otherwise there is no reason to expect a benefit, and the evidence generally shows no benefit and perhaps even increased risk. For the average healthy person, you are far better off focusing your attention of having a well-rounded diet with sufficient fruits and vegetables. Further, the evidence shows that supplementation does not make up for having a bad diet. It may treat a resulting deficiency, but won’t undo all the negative effects of an unhealthy diet. So again – focus on your diet, and don’t be lulled into a false sense of security because you take a multivitamin.

The other common fallacies in routine supplementation marketing is that if some is good, more is better. This flawed logic has even lead some to recommend so-called megadosing.  This is not how the body works, however. Organisms are complex adaptive homeostatic systems. Biochemistry is a complex intertwined web. For most components, there is an optimal range – too little, or too much, will throw the system off and be detrimental. So if you are getting enough of a nutrient, taking even more will not necessarily be a benefit, and logically is more likely to be harmful. The probability of harm increases with the dose, and every vitamin has an overdose syndrome associated with it as well.

Further the appeal to nature fallacy again is meant to lull the public into a false sense of safety and efficacy. Vitamins are natural, so they magically cannot cause harm, and the more the better.

There is always room for more evidence, and more nuance, in such a complex question as the net effects of various supplements in various populations and conditions. But there already is a large amount of evidence and it is converging on a consensus, with several recent large systematic reviews and meta-analyses with similar results.

  • For most people, just have a well-rounded diet with plenty of plant-based foods.
  • Prenatal vitamins are useful for women who are pregnant or planning to become pregnant
  • Targeted and evidence based fortification can be useful public health measures.
  • If you have a special medical condition, consult your physician about the proper evidence-based supplementation
  • Otherwise, vitamins and minerals should be supplemented according to need based on blood levels and medically monitored.
  • Routine vitamin supplementation, outside of these specific situations, is likely of no benefit and may in fact be a net harm.
  • Do not take megadoses of any vitamin or supplement, as increasing dose increases the risk of harm

Scientists will continue to do studies, and the specific recommendations will evolve as new data comes in. But I suspect we have already picked the low hanging fruit when it comes to diet and health. We have identified the big benefits and risk factors. We are now researching progressively smaller and smaller effects, with diminishing returns. We can debate endlessly, for example, about omega-3 supplements and heart disease, but the fact that we have not confirmed a significant benefit so far means that any possible remaining benefit must be small.

For the average person these nuances are probably not worth the time and effort to worry about. You are far better off looking at the big picture – have an overall healthy diet, exercise regularly, and address any medical conditions or special needs with a proper professional.

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