Oct 18 2012

Multivitamins and Cancer

Existing evidence does not support a health benefit from taking a routine daily multivitamin. That has been the bottom line conclusion of medical research over the last couple of decades. A recent study published in JAMA, however, is making headlines because it found a small but statistically significant decrease in total cancer incidence in men taking a multivitamin vs placebo. The study raises the question again about the total health effects of a daily vitamin.

First let’s take a look at the study:

A large-scale, randomized, double-blind, placebo-controlled trial (Physicians’ Health Study II) of 14 641 male US physicians initially aged 50 years or older (mean [SD] age, 64.3 [9.2] years), including 1312 men with a history of cancer at randomization, enrolled in a common multivitamin study that began in 1997 with treatment and follow-up through June 1, 2011.

The study found that the total incidence of cancer was 17.0 per 1000 person years in the multivitamin group, and 18.3 per 1000 person years in the placebo group. This difference was statistically significant. The study, however, found no statistically significant difference in any specific cancer (it was only the cumulative incidence that reached significance) and no difference in cancer mortality. Taken at face value this indicates a small but real decrease in total risk of cancer for older men taking a daily multivitamin.

I could not find any glaring flaws in the study, it seems well designed and executed. Individual studies, however, are rarely definitive in their findings. The most reliable studies have rigorous design, clear outcomes, large numbers, with a robust and statistically significant result. The results of this study are suspect mainly because the effect size was very small. Subtle confounding factors can reach statistical significance in very large studies, which is why small effect sizes are always suspect. There also appeared to be multiple comparisons in the study – specific cancers, different subgroups, and various outcomes (incidence and mortality), which creates the opportunity for spurious statistical outcomes.

The fact that this study looked at male physicians has an unclear effect on the degree to which it can be extrapolated to the general population. In general physicians take better care of themselves and are more compliant with treatments than the general population.

The results of this study, therefore, are interesting and plausible – there may be a small benefit in terms of total cancer risk from a daily multivitamin. But we have more than this one study to go by. Previous studies looking at the same question have had different results. The authors of this study summarize previous evidence:

In the Cancer Prevention Study II, which followed up more than 1 million US adults beginning in the early 1980s, multivitamin use was not associated with cancer mortality. The Women’s Health Initiative found that multivitamins had little or no relationship with the risk of breast, colon, or other cancers in more than 160 000 women followed up for a mean of 8 years. Among 35 000 Swedish women, however, multivitamin use was associated with a 19% increased risk of breast cancer (95% CI, 1.04-1.37) during a 10-year period compared with women not using these vitamins.

They further point out that observational studies have shown a protective effect, no effect, and even increased risk from multivitamins. Put into the context of the entire literature on this question, therefore, it remains unclear what the net effect of a daily multivitamin is on cancer risk and mortality. When multiple clinical trials of various designs show inconsistent and small results this could reflect the fact that there is little to no net effect, and we are just seeing random statistical fluctuations among trials. There could also be one or more systematic errors in the way the data is being looked at which is obscuring the real effect (whether positive or negative).

At this point about the only thing we can say with a high degree of confidence is that there is no large risk or benefit from taking a multivitamin. There may be a small benefit, no benefit, or even a small harm. The totality of existing data does not rule out any of those latter interpretations.

The best health recommendation also is not changed by this study, which is that the best advice is to eat a varied diet with lots of fruits and vegetables. If you do this you will very likely get enough vitamins from your diet that a supplement will be redundant. The benefits of having many vegetables in the diet is clear. Perhaps the biggest risk of taking a multivitamin is that it can create a false sense of security and justify other unhealthful behavior.

Meanwhile the question about the health effects of taking a multivitamin remains open. If anything, this study confuses the issue further because it is at odds with prior research.

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32 responses so far

32 Responses to “Multivitamins and Cancer”

  1. mindmeon 18 Oct 2012 at 11:24 am

    The press is running with headlines that suggest multivitamins protect against cancer.

    http://bo.st/U9lRnF

    You have to read very close to see it’s a mild effect on only older men. Not even sure if it’s statistically significant.

  2. petrossaon 18 Oct 2012 at 12:25 pm

    Otoh, also quite possible, a good sized part of those who take multivitamins do so for the reason they don’t feel well.

    A bit like the cannabis/schizophrenia connection. More schizo’s under the cannabis users because they are predisposed to selfmedicate.

    None of this is of much value.

    Jumping to conclusions is getting rampant these days.

  3. ccbowerson 18 Oct 2012 at 1:00 pm

    “At this point about the only thing we can say with a high degree of confidence is that there is no large risk or benefit from taking a multivitamin. There may be a small benefit, no benefit, or even a small harm. The totality of existing data does not rule out any of those latter interpretations.”

    This sums up the evidence over the past few decades nicely. The questions I always wonder are: Why do so many people feel the need to spend so much money on these things? Why is the general attitude by physicians that doing so is reasonable? I do not make a big deal out of it, but whenever a person asks me about multivitamins or OTC supplements, I generally suggest that the person is better off using that money to buy food in the produce section, or saving it towards something else.

  4. ccbowerson 18 Oct 2012 at 1:05 pm

    “…also quite possible, a good sized part of those who take multivitamins do so for the reason they don’t feel well.”

    There are many confounding variables that work in both directions, which makes these studies difficult to interpret given that the effects (if any) are pretty small. Although some may take multivitamins because they don’t feel well or because they know they have a poor diet, on the other side: people who are health fanatics or have extra money are also likely to take multivitamins.

  5. Fred Cunninghamon 18 Oct 2012 at 2:22 pm

    On CBS this morning Charlie Rose interviewed Dr David Argus about this subject. The doctor said that the benefit appeared to be confined to the subset that previously had cancer. His recommendation was pretty much the same as Steve’s i.e. eat a healthy balanced diet with plenty of fruits and veggies and that using a pill to make up for a poor diet won’t work.

  6. jt512on 18 Oct 2012 at 2:59 pm

    A p-value of .04? Are you serious? People need to stop worshiping statistical significance. A p-value of .04 is meaningless, especially in a large study.

    Using equations 13, 14, and 15, from my web site, we can estimate the Bayes factor for this finding. The Bayes factor is the ratio of the support that the data provide for the null hypothesis to the support that the data provide for the alternative hypothesis. Bayes factors less than one imply that the data favor the alternative hypothesis, whereas Bayes factors greater than one imply that the data favor the null hypothesis. The estimated Bayes factor for this study’s finding is 4.6, meaning that, in spite of its statistical significance, the finding favors the null hypothesis over the alternative by more than 4 to 1.

    Not only does this study not provide evidence that multivitamin uses decreases the risk of cancer, it actually provides evidence that it has no effect.

    Steve, I recall you mentioning once that you were in touch with E-J Wagenmakers. If you still are, consider running this by him. His feedback should be illuminating.

    Jay

  7. tmac57on 18 Oct 2012 at 5:44 pm

    I think I’ve got this thing figured out!
    I only take a multivitamin on the days that it provides a positive benefit,and skip it on the negative or neutral days.Those days I ride my bike 10 or 15 miles instead…so far so good ;)

  8. taobethon 19 Oct 2012 at 12:45 am

    Relative risk is at it again! I’m pleased to see a well-designed study, but that doesn’t absolve the depiction of the data.

    The claim is that men could reduce their cancer rates by 8% from taking a daily multivitamin. When I see a restricted domain, such as gender, I look for a difference that can be determined by gender. Given that only men can get prostate cancer, you might expect that is where the significance lies, but there was no correlation. Looking closer, we find that the study was only referring to a reduction in occurrences of total cancer. Beyond that, the difference was only recorded in the older population, and even more importantly, only older men with a baseline history of cancer. Looking at the figure below, you see that the men who never had cancer showed no benefit. This, to me, signals a red flag for confounding variables, such as previous cancer treatments received by the patients in this subgroup.

    http://jama.jamanetwork.com/data/journals/jama/0/m_joc120108f3.png

    If you look at the total incidence, the men without cancer had n=13229, and the men with baseline history had n=1312 occurrences. The graph without baseline shows pretty consistently that there is no correlation, and since the n is higher, this is more reliable. With only 1312 (about 10% fewer incidences) for the other group, and only a difference of P=0.02, how is this data either significant? Moreover, with a wealth of conflicting and inconclusive studies, how is this finding reliable before it has been duplicated?

    I feel if there were a realistic benefit, we should be able to see it across age, gender, and baseline history. Since the data showed no patterns about which specific types of cancer were inhibited (no correlation for all subgroups), I’d be more likely to believe that the recording was result of chance coincidence or error.

    I think JT hit the nail on the head with, “Not only does this study not provide evidence that multivitamin uses decreases the risk of cancer, it actually provides evidence that it has no effect.” Steven may have been a little forgiving on this one, in my opinion.

    Let us not forget that the study was funded by BASF Corp (a large multi-national chemical producer) and Pfizer (a large multi-national pharmaceutical developer).

    Oh, and in regards to the inverse causal relationship Petrossa mentioned: Although I agree the media loves to do that with any meager correlation, it does not apply in this instance because the two groups were randomized with placebo.

  9. taobethon 19 Oct 2012 at 1:30 am

    Bottom line, if it doesn’t improve quality of life or mortality, what good is it?

  10. SimonWon 19 Oct 2012 at 3:01 am

    Jay answered my first question with such a small effect, e.g. what is the chance it could occur by chance.

    I think there is a good scientific question to which I don’t have an answer, which is why taking multi-vitamins isn’t beneficial. One would think that any large study would have subgroups who are deficient in some vitamins, so multi-vitamins should help, or is it that the group of vitamins we’ve identified is too small compared to those we need from our food to be significant, or that our bodies cope with vitamin deficiency in other ways than allowing pathology (e.g. slowing down, breaking down proteins inside us).

  11. nybgruson 19 Oct 2012 at 7:58 am

    @simonw:

    I would argue that it is because, despite what the alties would have us believe, vitamin deficit of any clinical significance is actually not particularly common in developed nations. Furthermore, despite being a large n, they were all older physicians… People who not only have the knowledge to eat better than most, but more importantly no question that they have the means to. Your question about the actual outdoors of vitamin deficiency are reasonable to consider as well. And lastly, yes, there may be a facet of the multi vitamin not actually covering deficiency because it was too narrow a coverage. I think this is the least likely contributor though for a few reasons.

  12. KGellingon 19 Oct 2012 at 8:25 am

    “If you do this you will very likely get enough vitamins from your diet”

    You will not get enough vitamin D from diet alone (unless you eat 2 or 3 portions of fish every day).

  13. Karl Withakayon 19 Oct 2012 at 11:02 am

    KGelling

    “You will not get enough vitamin D from diet alone (unless you eat 2 or 3 portions of fish every day).”

    I suppose that partly depends on whether you consider the USRDA to be adequate.

    In the US, 1 cup of milk typically contains 25% of the USRDA of vitamin D. I drink a minimum of 1 quart of skim milk a day, and usually closer to 2 quarts. Therefore I am getting between 100% and 200% of the USRDA for vitamin D daily from milk consumption alone.

  14. KGellingon 19 Oct 2012 at 12:21 pm

    @Karl Withakay

    You can get the RDA from diet alone but diet is not the main source of vitamin D. We get most of our vitamin D from sun exposure. The RDA is a fraction of what is made by the sun.

    Try this – measure vitamin D, avoid the sun for 6 months whilst eating heathly diet, measure vitamin D.

    You’ll find that your vitamin D levels will drop by approx 1/3; and there’s no need to try it because this is what happens every year in the UK (latitude 50-55 N) between Oct and Mar and vitamin D levels here drop by about 10 ng/ml.

    PMIDs: 17344510, 2839537

  15. BillyJoe7on 19 Oct 2012 at 3:47 pm

    So, does the RDA of vitamin D assume adequate sun exposure?

  16. Karl Withakayon 19 Oct 2012 at 5:13 pm

    KGelling,

    “You can get the RDA from diet alone but diet is not the main source of vitamin D. We get most of our vitamin D from sun exposure. The RDA is a fraction of what is made by the sun.”

    I’m well aware of relationship between vitamin D & sunlight.
    I was responding only to your specific falsifiable claim of,

    “You will not get enough vitamin D from diet alone (unless you eat 2 or 3 portions of fish every day).”

    which you yourself have now contradicted.

  17. sonicon 19 Oct 2012 at 8:06 pm

    What population is this a random sampling of?
    That is the only population that one would make valid statistical statements about.

    This wasn’t a random sampling of any population, so the statistics are only valid for that specific group of physicians. If one wanted to generalize these results, one would have to show that the population tested is the equivalent of a random sampling from the population to be generalized about.

    Male physicians over age 50 in the USA are equivalent to what population’s random sample? I don’t know of one- I’m not sure it is even a random sample of male physicians over 50.

    Studies like these are interesting but they should only be used as preliminary. A real study has to be of a random sample (or a group that is equivalent to a random sample) of the population you want to generalize to.

    Do they teach this in a statistics class these days?

  18. petrossaon 20 Oct 2012 at 12:32 pm

    ccbowers: “people who are health fanatics or have extra money are also likely to take multivitamins.”

    Indeed so, and just as likely or unlikely to drop dead. One of the major causes of heart attacks is still exercise.

  19. ccbowerson 20 Oct 2012 at 1:49 pm

    “So, does the RDA of vitamin D assume adequate sun exposure?”

    Yes. The requirements change significantly for those with very limited sun exposure. Even 10-15 minutes of sun exposure can produce thousands of IU of vitamin D. The actual amount varies with time of year/intensity, skin color, etc. but it can dwarf dietary intake for those who spend more than a few minutes outside on a regualr basis.

  20. ccbowerson 20 Oct 2012 at 1:57 pm

    “Indeed so, and just as likely or unlikely to drop dead. One of the major causes of heart attacks is still exercise.”

    Sudden strenuous exercise can be a precipating factor for a cardiovascular event, but lets not forget that poor cardiovascular fitness shifts the bar for what is strenuous for a given person. I do not agree (I’m not sure if you are impying this or not) that cardiovascular fitness doesn’t matter, but exercise is necessary to become fit. How much is optimal is another question that I don’t think has been answered.

  21. locutusbrgon 21 Oct 2012 at 11:06 am

    You may have a heart attack sitting on you couch or sleeping. Having a good diet and body weight are factors but next to smoking, inactivity is the next highest risk factor. Sudden death in athletes will always be an emotive topic, for it suggests that athleticism may not prevent the development of heart disease and may actually increase the likelihood that the athlete will die suddenly during exercise. Persons who die suddenly during exercise have advanced heart disease of which they are frequently unaware. The commonest forms of heart disease associated with sudden death during exercise are coronary artery disease and hypertrophic cardiomyopathy. Less common cardiac conditions linked to sudden death in athletes include anomalous origin of the coronary arteries, aortic rupture associated with Marfan’s syndrome, myocarditis, mitral valve prolapse and various arrhythmias. The incidence of these predisposing diseases in the athletic population is extremely low, possibly of the order of 1 per 10,000 to 1 per 200,000 athletes. Detection of some of these conditions in asymptomatic athletes may be difficult, if not impossible. Regular exercise reduces the overall risk of sudden death in persons with latent coronary artery disease. yet acutely increases the risk of sudden death during exercise for those with heart disease that predisposes to sudden death. In practical terms, see your doctor get screened for sudden death risk factors and exercise regularly. Yes once a year shoveling snow and running a 5k without the surrounding exercise and no medical care is risky. If you follow the advice that is printed on every piece of exercise equipment, see your doctor before beginning an exercise program.

  22. petrossaon 21 Oct 2012 at 1:26 pm

    ccbower: “How much is optimal is another question that I don’t think has been answered.”

    To my it’s quite simple. As a certified petrolhead i compare it to a car.

    Let a car sit in a garage for years and it’ll rust solid, run it everyday hard it’ll breakdown.

    Easy does it. When i sit on my little seafront bench quietly pondering if it’s time to move already, i see dozens of runners pass me by. Of all of them i am 100% certain they will all pass away.

    Some of them whom are genetically predisposed will still be doing 100 km cycling at the age of 101 as a local did recently, most of them will just die around the average age.

    Of all interviews i ever seen of still capable centenarians not one of them was a healthfreak. Logical, because that fad didn’t exist till recently.
    Most of them suffered extreme hardship during WW2, never ran anywhere but after a bus. Some where still smoking, most of them drank alcohol and ate whatever they pleased.

    Practically all very aged people have very high cholesterol.

    In other words, you can do a lot to mess yourself up and die early, you can do very little to improve your genetically predisposed time of departure.

    Stressing your body hardly seems the way to enhance it’s survivability. Again this link is as tenuous as the link in the OP. Perhaps athletic people tend to live longer anyway, regardless of exercise.

    Anyroad when i see the poor guys whose doctor obviously told them to exercise, because that’s what he read in some paper, wobbling past my bench sweating looking like death warmed over, i’m pretty sure what he/she is doing is not doing anything positive to his body.

  23. BillyJoe7on 21 Oct 2012 at 4:43 pm

    I think the problem is using exercise for a health benefit.

    I exercise practically every day. I run for about an hour every weekday morning and run for a couple of hours through the local hills every Sunday morning. Three months ago I developed tendonitis as a result of tying my shoe laces too tight to improve my downhill runs. So I took up cycling which was unaffected by the tendonitis, and yesterday I completed the 210km Around The Bay ride.

    But I don’t do this for any health benefit. I just love the exercise. It’s quite exhilarating to run through the hills, especially the downhill runs. It was also quite a bit of fun mixing it with twenty thousand riders in the around the bay ride. And pretty satisfying to complete it exhausted but in good shape because of well tuned preparation for the ride and perfect pacing during the ride.

    If there are any health benefits, that is merely peripheral. But if I compare my unfit self before the age of twenty-eight and now, I feel much better able two cope with whatever rocks life throws at me. Fitness and stamina is not only for longevity. It is for the here and now. As is the enjoyment of whatever activity you chose to do. Try it sometime.

  24. BillyJoe7on 21 Oct 2012 at 4:44 pm

    …that was for petrossa

  25. taobethon 22 Oct 2012 at 2:21 am

    No offense, guys, but the cardio/chd/cholesterol/exercise comments are getting way off subject, and some of the statements are merely myth, conjecture, or anecdote not supported by current research. It is a very interesting, controversial, commercialized, and politicized topic, though. If you want to intimately discuss those studies, we should suggest that the blogmaster covers them separately, because it is a very big, deep, complex topic with a lot to untangle.

    “I would argue that it is because, despite what the alties would have us believe, vitamin deficit of any clinical significance is actually not particularly common in developed nations. ” -nybgrus

    You’re totally right. Data easily accessible on the WHO website. One of the most prominent worldwide deficiencies, Vitamin A, is consumed at almost overdose quantity in affluent countries. Funny thing is, it’s usually the alties that end up with the deficiencies from diet restriction. lol. Just wait until our vegan culture ages and finds out what vitamin k2 deficiency is all about. Otherwise, it is the result of another illness or other medical complication, rather than diet. Most my life, I was anemic (despite popping iron pills daily) due to wheat intolerance. Who knew? lol

    “Furthermore, despite being a large n, they were all older physicians… People who not only have the knowledge to eat better than most, but more importantly no question that they have the means to.” -nybgrus

    “Male physicians over age 50 in the USA are equivalent to what population’s random sample?” -sonic

    These are significant observations. The difference was shown in male physicians over 50 with baseline history of cancer (read: cancer treatments). I imagine they would have more access to advanced prolonged medical care, as well, creating a web of confounding factors. A random sampling would be far stronger evidence, but at least within the subset, they were randomly assigned.

    Another note of importance is that there is no link between nutrition and two thirds of cancer types, and a weak correlated link for some of the rest. For the case to be improved, they would have to show a link between the cancers presumably impacted by diet, such as colorectal cancer, pancreatic cancer, etc. As you can see in the following graphs, pancreatic cancer mortality was the same for both groups. Colorectal cancer LOOKS as if there’s a significant difference, until you notice how they re-gauged the y-axis. Sneaky.

    http://jama.jamanetwork.com/data/journals/jama/0/m_joc120108f2.png

    http://jama.jamanetwork.com/data/journals/jama/0/m_joc120108t2.png

  26. KGellingon 22 Oct 2012 at 12:27 pm

    @BillyJoe7

    The current RDA for vitamin D assumes ‘minimal sun exposure’ (which is one of the reasons why the new recommendations have been criticised).

    @Karl Withakay

    I’m not sure what the contradiction is (or are you just trolling?).

    If your only source of vitamin D is your diet – so no sun exposure at all – then you’ll become vitamin D deficient.

    To have enough vitamin D you either have to have a skewed diet (lots of fish) which is therefore not ‘healthy’ in the implied sense or supplement with sun exposure and/or supplements.

  27. petrossaon 22 Oct 2012 at 1:31 pm

    Unfortunately, there is high prevalence of vitamin D deficiency due to lack of proper diet, poor calcium intake, social customs and remaining confined to the four walls of primitive housing that deprives the elderly, children and female population of the benefit of the sunshine.

    http://www.pjms.com.pk/issues/octdec208/pdf/review01.pdf

    In other words being religious is also not good for your health, but they couldn’t write that down

  28. Karl Withakayon 23 Oct 2012 at 10:36 am

    KGelling,

    “If your only source of vitamin D is your diet – so no sun exposure at all – then you’ll become vitamin D deficient.”

    Granted, if you have sufficiently inadequate exposure to sunlight or UVB, but this statement:

    “To have enough vitamin D [in zero sunlight] you either have to have a skewed diet (lots of fish) which is therefore not ‘healthy’ in the implied sense or supplement with sun exposure and/or supplements.”

    does not follow.

    “You will not get enough vitamin D from diet alone (unless you eat 2 or 3 portions of fish every day).”

    Let’s look at some numbers: 3 portions of fish, with say ~325 IU vitamin D3 each (averaging 5 different fish sources of D)= about 1000 IU

    at ~125IU / server (1 cup), that comes out to around 8 cups of milk a day. That’s 2 quarts of milk (ignoring any other dietary sources of D) a day, which is a lot, but not an excessive amount. It is, in fact, about my usual daily intake of milk.

    Could you perhaps state what you understand to be the required daily intake of D (all sources) so that I can know what number you believe is unreachable through diet alone?

  29. KGellingon 24 Oct 2012 at 4:43 pm

    @Karl Withakay

    (last one)

    1. A good rule of thumb is 100 IU/d ~ +1 ng/ml, so 1000 IU/d ~ +10 ng/ml which is how much vitamin D levels drop in the UK in autumn/winter.

    2. 2 quarts of milk a day is a l-o-t of milk

    3. Milk is fortified with vitamin D !!! I guarantee that I can get enough of anything if I eat/drink something that is fortified with it

  30. Karl Withakayon 24 Oct 2012 at 5:22 pm

    @KGelling

    You can throw out “(last one)” as a hand grenade and refuse to respond if you wish to do so, but that does not means you get a free pass on your points.

    1. OK, 1000 IU is your number, which is the number I also used.

    2. 2 quarts of milk / day is a good amount of milk, but if you break it down, it’s not unreasonably excessive:

    Two quarts (64oz) is 8 X 8 oz cups. Spread across 3 meals a day (and remember, we are assuming zero vitamin D from any other dietary sources here), that’s only 2-2/3 cups per meal. That’s ~21 oz of milk per meal (assuming that one only consumes milk as part of a meal), which is just one large mug of milk per meal. 21 oz, for example, is the size of a single medium beverage at McDonald’s.

    It’s certainly more than most people drink, but we’re not really discussing what most people drink; we’re discussing what’s reasonably possible through diet. My “milk mugs” at home are 22 oz to the brim.

    3. “I guarantee that I can get enough of anything if I eat/drink something that is fortified with it”

    Yes, milk is fortified with vitamin D3. Many foods we eat are fortified. What’s your point? You never mentioned not consuming fortified foods as part of one’s valid dietary sources of vitamin D.

    Your claims were:

    “You will not get enough vitamin D from diet alone (unless you eat 2 or 3 portions of fish every day).”

    and later

    “To have enough vitamin D [in zero sunlight] you either have to have a skewed diet (lots of fish) which is therefore not ‘healthy’ in the implied sense or supplement with sun exposure and/or supplements.”

    those two statements have been demonstrated to be false 9at least in the US), excepting if for the second statement, you are considering fortified foods to be supplements. In any case, the first statement is has been unquestioningly demonstrated to be false.

    When you consider that the overwhelming majority of milk sold in the US is fortified with vitamin D3, milk cannot be considered an atypical dietary source of vitamin D in the US.

    Are you now qualifying your position to be more nuanced than originally presented?

  31. Mlemaon 30 Oct 2012 at 11:21 pm

    I didn’t see anything in the study about asking the participants to refrain from eating vitamin-fortified foods. Many packaged cereals have added vitamins. The participants might have been getting lots of vitamins outside the study..

    PS – Karl Withakay: Vit D is fat soluble, so if you’re drinking fortified skim milk to get the Vit D you might absorbing less than what’s advertised (unless you’re eating some fatty food with it)

  32. Mlemaon 30 Oct 2012 at 11:25 pm

    (meaning that those taking the placebo might be getting as much vitamin as those given the study’s vitamins – so not able to tell as easily what the real effect would be)

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