Vitamin D and Fish Oil May Help Prevent Cancer Death, Heart Attacks

While cancer rates were not affected, those who participated in the experiment had better cancer survival rates
June 8, 2020 Updated: June 8, 2020

Sought-after nutritional therapies vitamin D and omega-3s found in fish oil have gone through intense scrutiny with the largest study to date, called VITAL. Results of the study on whether they can effectively prevent cancer or cardiovascular disease have shown that these therapies are popular for a reason, and the benefits simply cannot be ignored.

In a span of more than five years of research and treatment, the VITamin D and OmegA-3 Trial, or VITAL, has tested the rigor of benefit claims around vitamin D and omega-3 fatty acids (found in fish oil) against the rates of cancer mortality and heart attacks.

While the primary endpoints of the study, which involved 25,871 men and women in a nationwide survey, showed no significant reductions, notable benefits emerged and offered a strong case for both further studies and supplementation.

Study Details

The randomized clinical trial set out to prove whether taking daily supplements of vitamin D3 (2,000 international units of D3 or cholecalciferol) or omega-3 fats (1 gram of fish oil) reduced the risk of developing cancer, heart disease, and stroke in individuals without a prior history of these conditions.

Prior to the trial, results were mixed but show promise for certain outcomes, now confirmed by updated meta-analyses. According to the scientists, large primary prevention trials on the two therapies using adequate dosing in general populations were previously lacking.

The subjects were randomly assigned to one of four groups: daily intake of vitamin D and omega-3s, daily vitamin D and omega-3 placebo, daily vitamin D placebo and omega-3s, and daily vitamin D placebo and omega-3 placebo. All of them took two pills every day, as well as filling out a short questionnaire every year on their health, lifestyle habits, family history of illness, and new medical diagnoses.

Nearly 17,000 of the participants provided an optional blood sample at baseline, while about 6,000 provided a follow-up blood sample from years 1 to 5 of the trial. At the start, year two, and year four, a sub-cohort of 1,054 subjects had a clinical exam and underwent further evaluations.

Significant Benefits That Cannot Be Ignored

After more than five years of research, the study concluded that major cardiovascular events and total invasive cancer weren’t significantly reduced by omega-3 or vitamin D3. However, several important benefits surfaced from the findings:

Fish oil reflected a small yet insignificant decrease in the primary cardiovascular endpoint of major heart disease events but was linked with meaningful reductions in heart attacks.

Omega-3 substantially slashed total myocardial infarction, especially among African Americans and those who had lower fish intake at the beginning of the study. The associated heart benefits have been confirmed by recent meta-analyses of omega-3 randomized trials.

Vitamin D supplementation didn’t decrease major cardiovascular disease events or total incidence of cancer, yet was associated with a statistically important reduction in total cancer mortality among people who participated in VITAL for at least two years. Vitamin D’s effect in reducing cancer death has been confirmed by meta-analyses, too.

Dr. JoAnn Manson, a lead study author from Brigham and Women’s Hospital, said the pattern of findings suggests a “complex balance of benefits and risks” for every intervention, identifying the need for further research on who will most likely benefit from the supplements.

Why You Need Your Fix of Sunshine and ‘Good’ Fats

The health benefits of vitamin D are widely documented. has collected research documenting more than 200 health conditions that may benefit from optimized vitamin D levels.

These vitamin D benefits include pain-killing or analgesic properties, increased subcutaneous fat metabolism or better fat loss, and even longer human lifespan. You can find some 1,000 abstracts with vitamin D research on

Sunlight is a well-known source of vitamin D, but in the absence of adequate sun exposure and other factors, supplementation proves to be an effective source of the nutrient.

Meanwhile, have you ever wondered why you may need to supplement essential fatty acids? Ideally, eating cold-water fatty fish 2 or 3 times a week is an efficient way to obtain enough omega-3s in your diet, particularly the anti-inflammatory (EPA) and brain-assisting (DHA) fatty acids.

However, the standard American diet has been found to sorely lack the omega-3s you need, being disproportionately filled with omega-6s. Even with fish oil supplementation, absorption is only improved when the supplement is consumed with a meal that includes fat. Multivitamins also typically don’t contain essential fatty acids in their roster.

The human body contains some 15 percent to 30 percent fat, and that dietary fat offers an alternative fuel source when there isn’t glucose. Healthy fats are satiating, help burn fat, and balance a number of fat-regulating hormones in the system.

The database provides about 600 abstracts with research on omega-3 benefits, including inflammation, Type 2 diabetes, depression, and cardiovascular diseases.

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