Studies have associated omega-3 fats and vitamin D3 with better health including lower rates of cardiovascular disease like stroke and heart attacks, and lower rates of cancer.
A lot of research in the past has look at the role of these nutrients in preventing disease, or worsening of disease in groups of people who are at high risk of those illnesses. What we don’t really know is if omega-3 and vitamin D3 supplements provide any benefit (prevent diseases) in the general population with so-called ‘average’ risk.
Enter The VITamin D and omegA-3 TriaL, a.k.a. the ‘VITAL’ study
The VITAL study
VITAL is an ongoing research study in 25,871 men and women across the U.S. investigating whether taking daily dietary supplements of vitamin D3 (2000 IU) or omega-3 fatty acids (1 gram with 460 mg EPA and 380 mg DHA) reduces the risk for developing cancer, heart disease, and stroke in people who do not have a prior history of these illnesses.
Preliminary results are out
After waiting 2 long years, trust me, that felt like an eternity, preliminary results came out on November 10, 2018.
The New England Journal of Medicine published two results papers: one paper comparing those assigned to vitamin D3 (2000 IU/day) vs. placebo and another paper comparing those assigned to omega-3s (1000 mg/day) vs. placebo.
You may have read in the news that this study showed that neither vitamin D nor omega-3s prevent cancer (all kinds of cancer analyzed together) or heart disease (a composite of all types of heart disease).
Reporting the results like this? So not helpful. 🙁
Does it might for sensationalized headlines? You bectcha it does.
To group all cancers together and all forms of heart disease together and then make large sweeping conclusions about them as if we’re talking about a single entity is pretty useless. If you gave a specific dose of ibuprofen to look at pain relief and grouped all the results together, you wouldn’t know if the given dose helped with headaches but not muscle sprains.
One way around this is to look at sub-group results (this looks at results in different groups of subjects). This will give information to see if something (vitamin D3 and omega-3s) is helpful or not for specific situations such as different types of cancer or heart disease in different groups of people.
The good news? Although not reported on the news and by now swept to the sides; we have those sub-group results!
Enough already, what did they find?
VITAL did show several benefits with a consistent, relatively moderate, daily dose of both vitamin D3 and omega-3 fats
Key outcomes with 1000 mg/day of omega-3 fatty acids (460 mg EPA, 380 mg DHA or 1 gram)
- 28% reduced risk of heart attack (p ≅ 0.002)
- 22% reduced risk of percutaneous coronary intervention (stent) (p ≅ 0.02)
- 17% reduced risk of total coronary heart disease (heart attack, PCI and CVD death) (p ≅ 0.02)
- 50% reduced risk of death from heart attack (p ≅ 0.04)
- 77% reduced risk of heart attack for African American participants (p<0.0001)
- 40% reduced risk of heart attack for participants with a fish consumption of less than 1.5 servings/wk (p ≅ 0.0007)
Although it was reported in the headlines that there was no benefit for “heart diease” or “all cancers”, a closer look at the separate types of heart disease or death from cancer were analyzed, there were 30 different very significant results.
For a larger view, click this link: Risk reduction with Vitamin D and Oemga-3s. VITAL Trial Results
Some of the more nerdy/technical stuff (skip to the end if you just want the bottom line)
Statistically Significant Vitamin D3 Results from Pre-specified Secondary Outcomes and Subgroup Analyses
Vitamin D3 vs. Placebo
Cancer Mortality (deaths)
(excluding first two years of follow-up)
25% reduced risk (p=0.02)
Primary Outcomes – Subgroup Analyses
|24% reduced risk (p=0.003)|
|23% reduced risk (p=0.056*)|
Researchers can also, and often do publish results on outcomes that were not pre-specified (i.e. post hoc), but these results are considered preliminary because they are typically added once a pattern has been discovered in the data and therefore have a higher false-positive risk. The VITAL trial reported a few statistically significant post hoc tests for those assigned to omega-3 vs. those assigned to placebo which can’t be ignored.
Statistically Significant Omega-3 Results from Post-Hoc Outcomes
Death from Heart Attack
50% reduced risk (p=0.04)
Percutaneous coronary intervention (PCI; stent)
22% reduced risk (p=0.02)
Coronary heart disease (heart attack, PCI, CVD death)
17% reduced risk (p=0.02)
What should you do at the end of the day?
Don’t toss your vitamin D3 or omega-3 supplements if you’re taking them. If you’re not taking any, seriously consider adding them.
The effects from vitamin D3 were not as prolific as those from the omega-3’s likely due to the relatively low dose of vitamin D3 given (2000 IU/day) used in this study. Physiologically speaking, the amount of vitamin D3 used is nothing compared to the amount of omega-3 fatty acids that can be obtained with food.
Foods rich in omega-3 fats can easily provide 1 gram of EPA and DHA. One, 100 g can of sardines has about 900 mg, a can of sockeye salmon gives a whopping 2800 mg. To get meaningful benefits from omega 3 fats, research has shown you’d need to get about 1 gram or more per day. This can and does happen for those who eat fish and seafood regularly and by regularly I mean several times a week, if not daily.
You might think, “oh, getting 1 gram of omega-3 fatty acids is easy” but consider this. Most Canadians only get a wimpy 140 mg per day on average. Only 10% of the population get over 250 mg per day. #tragic
Conversely, under ideal conditions, humans can make between 4000 to 10,000 IU of vitamin D per day (caveat, only under ideal conditions). This is of course is irrelevant because this DOES NOT happen in Canada due to our northern climate.
To get to a vitamin D blood concentration of 100 nmol/L (40 ng/ml), most people are looking at much more than 2000 IU per day. If they used a higher dose in the VITAL study, a more “physiological dose”, the benefit from vitamin D3 might have been in the same realm as that from the omega-3s.
Given the significant positive effects of vitamin D3 on cancer death and omega-3 on cardiovascular health found in the VITAL trial (which is supported by many other studies), and the fact that these supplements are safe and inexpensive, daily supplementation is beneficial.
Further, vitamin D and omega-3 blood level testing should be used to personalize the amount since there is a large range of variability in the response to a particular dose. For omega-3s in particular, this is where the omega-3 index comes into play but that might be a topic for another blog post.