Omega 3 and Diabetes, the ASCEND Study Reveals Benefits and Useful Dosages

Omega-3 fatty acids, allies of cardiovascular health, may protect against diabetes risks. A new study helps understand when and in what doses to take them, and what benefits are worth expecting.

Is it worth taking Omega-3 to protect the heart and arteries from the risks inherent in diabetes? Years of research have shown the importance of these fats for heart health; a new study helps understand when and in what doses they should be taken and what benefits can be expected from this supplementation. 

Published in the New England Journal of Medicine and conducted at the University of Oxford in the United Kingdom, the study involved over 15,000 patients with diabetes, monitoring their health for an average of 7.4 years. About half of the patients were asked to take a daily capsule of Omega-3; the other half were given olive oil.

Data published suggest that, in the absence of cardiovascular problems for those living with diabetes, taking Omega-3 or olive oil makes no difference. However, a deeper analysis reveals benefits in terms of reduction in vascular-related deaths. Furthermore, the advantages of taking Omega-3 may be more evident with the administration of adequate doses of these essential fatty acids.

• Diabetes and cardiovascular risk
• Omega-3 and cardiovascular risk
• Omega-3 and diabetes: the study
• The importance of patients’ nutritional status
• Omega-3 against diabetes: a feasible path

Diabetes and cardiovascular risk

Cardiovascular diseases are among the leading causes of death for people living with type 1 diabetes, and from this perspective, even the heart of those who develop type 2 diabetes cannot be considered safe: this form of diabetes is also associated with an increased incidence of cardiovascular problems and mortality from heart and artery disorders. 

Most studies on the subject have been conducted specifically on patients with type 2 diabetes and estimate an increase in coronary artery disease and ischemic stroke ranging between 2 and 4 times; the increase in mortality is estimated to range between 1.5 and 3.6 times. Additionally, type 2 diabetes is an important risk factor for heart failure, peripheral arterial insufficiency, and microvascular complications – all issues that negatively affect both quality and life expectancy, reducing the latter by 4 to 8 years in the presence of diabetes. The basis for this increased cardiovascular risk lies in well-known problems:

• Hypertension, which is associated with insulin resistance. It is common for diabetes to be associated with hypertension, and this combination doubles the cardiovascular risk;
• Increased levels of triglycerides and LDL (Low Density Lipoproteins, also known as “bad cholesterol”) and decreased levels of HDL (High Density Lipoproteins, “good cholesterol”). This combination of factors is characteristic of a problem linked to insulin resistance, called atherogenic dyslipidemia, which in diabetes is known as diabetic dyslipidemia.

Omega-3 and cardiovascular risk

On their part, Omega-3s have attracted researchers’ interest precisely because of their connection with cardiovascular health. The first studies to reveal their heart-healthy properties date back almost fifty years, when it was observed that among the Greenlandic Inuit populations, heavy consumers of fish rich in these fatty acids, the incidence of atherosclerosis was significantly reduced. The large body of scientific work since then has allowed the European Food Safety Authority (EFSA) to conclude that Omega-3s legitimately possess several health benefits, including:

• The ability to contribute to the normal functioning of the heart and to maintaining blood pressure and triglyceride levels within the normal range, attributable to the two Omega-3s found in fish: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA);
• The ability to contribute to maintaining normal cholesterol levels, attributable to the precursor of EPA and DHA, alpha-linolenic acid (ALA).

For these reasons, the prospect of protecting the heart and arteries of those living with diabetes through an approach based on Omega-3 intake appears entirely reasonable.

Omega-3 and diabetes: the study

The Oxford researchers’ study is not the first to test the hypothesis that Omega-3 intake may help combat the cardiovascular risk associated with diabetes. For example, in patients with type 2 diabetes, EPA intake (compared to placebo) has been associated with a significant reduction in triglycerides and non-HDL cholesterol. 

This new study instead shows a lower incidence of vascular-related deaths among participants who took Omega-3 compared to those who took the olive oil placebo. The difference (196 cases versus 240) is statistically significant. However, the authors of this new trial suggest that additional benefits could be obtained by modifying the dosage of Omega-3 given to patients. In this case, the researchers limited the intake to 840 mg of EPA+DHA per day but noted that “triglyceride levels can be reduced by administration of higher doses of Omega-3 fatty acid supplements than those used in our study (typically, 2 to 4 grams per day).” 

In general, randomized clinical trials published in scientific literature have shown that Omega-3 supplementation helps significantly reduce triglyceride levels and that its effect increases both with treatment duration and with increasing Omega-3 dose. Unfortunately, this study did not include measuring participants’ blood triglyceride levels, but its authors emphasize that “a reduction in triglyceride levels may produce beneficial effects in some patients with diabetes.” Additionally, another factor to consider is the ratio of EPA to DHA consumed. 

This new study administered 460 mg of EPA and 380 mg of DHA, corresponding to an EPA/DHA ratio of 1.2. However, analyses published in the past have shown that the reduction of triglycerides in patients with type 2 diabetes is more significant when this ratio is at least 1.5; the same seems to apply to cholesterol.

All this suggests that treatments based on higher doses of Omega-3 and characterized by a higher EPA/DHA ratio may be associated with significant cardiovascular benefits for people living with diabetes.

The importance of patients’ nutritional status

When analyzing results, it is also important to consider patients’ nutritional status. Experts involved in the study published in the New England Journal of Medicine stated that participants who took Omega-3 had a rather high Omega-3 Index (an indicator of the amount of EPA and DHA present in the blood), “close to what we would consider a baseline level for a protective effect.” In other words, this study may have involved patients who in reality did not need to take the Omega-3s administered to them because they already had enough. Indeed, most participants, if they had not taken Omega-3, would not have been at high risk of suffering a serious vascular event in the following 5 years: 40.4% were classified as low risk (below 5%), 42.3% as moderate risk (between 5 and 10%), and only a much smaller 17.2% as high risk (at least 10%). 

Dietary intake of Omega-6 fatty acids may also have made a difference. Very abundant in modern Western diets, if consumed in excessive amounts these fatty acids can contribute to jeopardizing heart health. For this reason, it is important to also evaluate the ratio between Omega-3 and Omega-6 intake – about which, unfortunately, the Oxford researchers’ study gives no indication.

Omega-3 against diabetes: a feasible path

Available data therefore suggest that Omega-3 supplementation could bring real benefits to people living with diabetes and that what can make a difference in the effect obtained are the health conditions of those taking them, the dose of Omega-3 taken, and the EPA/DHA ratio. In other words, in cases where it may really be necessary, taking appropriate amounts of Omega-3 seems potentially useful even in diabetes. For now, let us remember that according to EFSA, to help the body maintain triglycerides and blood pressure within normal levels, respectively, 2 and 3 grams of EPA+DHA per day are necessary. To help the heart work well, only 250 mg per day are sufficient. Finally, to maintain cholesterol within the normal range, 2 grams of ALA per day are necessary.   

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