Helps fish oil with pre-diabetes

Vitamin D and omega-3 fatty acids cannot maintain kidney function in type 2 diabetes

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Seattle - Dietary supplements with omega-3 fatty acids in fish oil capsules or with vitamin D did not slow the gradual decline in kidney function in patients with type 2 diabetes in a randomized clinical trial. The results were presented at the Kidney Week conference in Washington and in the American medical journal (JAMA 2019; DOI: 10.1001 / jama.2019.17380) published.

More than a quarter of all diabetics, most of them people with type 2 diabetes, have chronic kidney failure with a faster decline in the estimated glomerular filtration rate (eGFR) than normal age. Type 2 diabetes has now become the most common cause of dialysis and kidney transplants.

In a number of epidemiological studies, vitamin D deficiency (common in old age and in northern latitudes) in diabetics was associated with an accelerated decline in eGFR and the occurrence of albuminuria. The same applies to a deficiency in omega-3 fatty acids. Animal studies provided a credible foundation: Vitamin D and omega-3 fatty acids reduced the histological features of diabetic nephropathy there.

It was therefore expected that the VITAL-DKD study ("Vitamin D and Omega-3 Trial to Prevent and Treat Diabetic Kidney Disease") will show that supplementation with cholecalciferol (2000 IU / day) and / or with the Omega -3-fatty acids eicosapentaenoic acid and docosahexaenoic acid (1 g / day) can reduce the development and progression of renal insufficiency in diabetics.

The study was part of the larger VITAL study, in which 25,871 men (over 50 years of age) and women (over 55 years of age) took part and which examined the benefits of vitamin D and omega-3 fatty acids in the primary prevention of cardiovascular diseases. Illnesses and cancer should prove. The disappointing results of the VITAL study were presented at the American Heart Association's annual meeting last year. The food supplements had proven to be ineffective in primary prevention in people with a deficiency in the two essential substances (NEJM 2019; 380: 23-32 and 33-44).

Before the start of the study, a group of 1,312 participants suffering from type 2 diabetes had been selected for the VITAL-DKD study. At the start of the study, the patients had a mean eGFR of 85.8 ml / min / 1.73 m2, which was almost in the normal range (over 90 ml / min / 1.73 m2). Only in 16% was the eGFR below 60 ml / min / 1.73 m2 decreased (indicating moderate renal insufficiency) and microalbuminuria of more than 30 mg / g creatinine was only 9%.

Over the course of the 5-year study, the eGFR fell to 73.5 ml / min / 1.73 m2. This significant loss of kidney function could not be stopped by taking vitamin D or taking the fish oil capsules.

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As Ian de Boer from the University of Washington in Seattle and coworkers report, the loss of kidney function in the vitamin D group was 12.3 ml / min / 1.73 m2 only slightly lower than in the placebo group with 13.1 ml / min / 1.73 m2. In the group who took fish oil capsules regularly, the eGFR fell by 12.2 ml / min / 1.73 m2.

The differences to the placebo group were not clinically relevant and not statistically significant for either supplement. It should also be taken into account that kidney stones were slightly more common when taking vitamin D (32 versus 26 cases in the placebo group). Omega-3 fatty acids were more frequently associated with gastrointestinal bleeding (28 versus 17 cases in the placebo group).

Based on the results, diabetics cannot be advised to take either dietary supplement. With the VITAL study, a series of randomized controlled studies with negative results has continued for both substances. Vitamin D was unable to lower systolic blood pressure in patients with pre-hypertension and stage 1 hypertension (Circulation 2015; 131: 254-262).

The high-dose monthly oral intake of vitamin D also did not protect against cardiovascular diseases and premature death (JAMA Cardiology 2017; 2: 608-616) and it did not prevent blood sugar from deteriorating further in people with prediabetes (NEJM 2019; 381: 520-530).

The evidence is somewhat more favorable for omega-3 fatty acids. The fish oils could not protect the patients with diabetes from cardiovascular diseases (NEJM 2018; 379: 1540-1550). Because of the beneficial effects on triglyceride levels (NEJM 2019; 380: 11-22) however, they have recently been recommended by the American Heart Association. © rme / aerzteblatt.de