More than 29 million Americans have diabetes and 86 million have prediabetes. Sixty percent of type 2 diabetes patients will develop diabetic retinopathy (DR) within 20 years and 35% to 40% will develop diabetic retinopathy within 5 years.¹ Physician Recommended Nutriceuticals (PRN) offers a novel medical food, Nūretin, which is formulated with a purified triglyceride form (rTG) of omega-3 fatty acids to reduce the risk, and to slow progression, of diabetic retinopathy (DR).

Data demonstrate that patients who have DR may benefit from concentrated docosahexaenoic acid (DHA) omega-3 supplementation, as it may decrease the risk of developing sight-threatening DR and further improve diabetic macular edema when combined with intravitreal ranibizumab compared to intravitreal ranibizumab alone.^2-5 Furthermore, specific formulations and dosages of the long-chain omega-3 fatty acids eicosapentaenoic acid (EPA) and DHA, such as those found in Nūretin, may support retinal cellular metabolism, structure, and function.⁵

Retinal vascular degeneration has several stages, all of which have been shown to be ameliorated with the introduction of omega-3s EPA/DHA, especially DHA, says Michael Gross, MD, FACOG, senior vice president and chief medical officer for PRN.

Another study⁶ indicated that nutritional intervention with omega-3 polyunsaturated fatty acids (PUFAs), which include EPA/DHA as contained in Nūretin, was therapeutic for DR. This therapy also reduced omega-6 fatty acids, which further contribute to the growth of abnormal blood vessels in the retina leading to DR.

“Other than well-recognized thermal laser photocoagulation and intravitreal pharmaceutical modalities for effectively reducing edema and improving visual acuity in patients with diabetic retinopathy and diabetic macular edema, few other treatments are backed by multiple clinical studies,” says Daniel F. Kiernan, MD, FACS, a vitreoretinal surgeon with Ophthalmic Consultants of Long Island. “Nūretin is one such treatment.”

FIRST OF ITS KIND

Nūretin is the first nonprescription, evidence-based medical food for DR patients. “Nūretin is classified as a medical food because the formula is derived from clinical trials for which the product makes specific medical efficacy claims,” Dr. Kiernan says.

Two capsules daily provide 1,200 mg rTG EPA/DHA in a 1:5 ratio. “PRN was the first to recognize this unique formulation of EPA/DHA molecules and their effect on the retina,” says James Thimons, OD, FAAO, ophthalmic medical director for Ophthalmic Consultants of Connecticut. “That’s why I recommend it to my patients. I don’t know of any other product available in the United States with this exact formulation.”

Dr. Kiernan explains that the eye, and the retina in particular, contains a very high percentage of DHA, which as an essential nutrient cannot be made or stored by the body; it can only be acquired from a food source. Additionally, exocrine function, including lipid metabolism, is compromised in a significant portion of diabetic patients — especially those with excess weight (body mass index >25),⁷ so absorbing this nutrient is more difficult for them.

“Because Nūretin contains a highly absorbable form of DHA, it helps to correct an important potential nutritional deficiency that may not be corrected even with a normal, healthy diabetic diet,” Dr. Kiernan says. “This may help maintain vision and delay the onset and progression of DR.”

Another reason to consider Nūretin, according to the company, is that not all omega-3s are created equal. Nūretin in the rTG form intrinsically has greater bioavailability than other omega-3 products. A study comparing different forms of concentrated omega-3 fatty acid concentrations concluded that the rTG form has superior absorption and bioavailability (124%) compared to ethyl ester forms (73%) or even natural raw fish oil (91%).⁸ Due to heavy metals, especially mercury, contaminating some fish, native oil requires a microdistillation step to remove these contaminants, leaving the oil in an ethyl ester form, which is less biocompatible and less absorbed than the natural triglyceride form. A more expensive step involving transesterification is required to generate the rTG form. “Nūretin contains the rTG formulation, whereas the raw or ethyl ester formulation is found in the majority of other omega-3-containing fish oil products,” Dr. Kiernan says.

HOW IT WORKS

Diabetes decreases the functionality of the pancreas, which is responsible for producing enzymes that are necessary to digest foods, Dr. Gross explains. Recent research⁹ shows that as many as 74% of diabetic patients have a compromised ability to digest and absorb fat, further adding to the nutritional implications of an imbalance or deficiency of PUFAs.

This inability to absorb and use fats, specifically DHA, in addition to not managing blood sugar levels, leads to damage of the blood vessels of the light sensitive tissue in the retina and ultimately vision loss.

DHA assists in blocking the cellular pathways that create inflammation in diabetic patients, Dr. Thimons says. By blocking inflammation specifically in the retina, the risk that the inflammation will cause vessel damage resulting in retinopathy is decreased.

PATIENT RESPONSE

As a medical food, Nūretin is indicated for patients with prediabetes or diabetes with or without DR — which can be at any stage. “The sooner the product is used in this continuum, the better. Ideally, a patient takes it before any vision loss or visible retinal vascular signs have occurred,” Dr. Gross says.

“Until now, we haven’t enjoyed a capacity to intervene for patients at an earlier stage of the diabetic process,” says Dr. Thimons.

Because the product has only been available since March 2018, it is too early to assess patients who have taken Nūretin. However, Dr. Thimons says patients have tolerated it well, without any gastric concerns or systemic complications.

Nūretin must be distributed through physician recommendations. “When I prescribe Nūretin, I tell patients that it is part of a multiprong approach to improving their long-term retina health,” Dr. Thimons says. “Other aspects include modifying diet as per my recommendations, increasing exercise levels to a regular and consistent process, and decreasing weight to an ideal weight. Patients are receptive to this discussion, as they want to do something to improve their health and take a more proactive role in managing their overall diabetic condition.” RP

REFERENCES

1. Yau JW, Rogers SL, Kawasaki R, et al; Meta-Analysis for Eye Disease (META-EYE) Study Group. Global prevalence and major risk factors of diabetic retinopathy. Diabetes Care. 2012;35(3):556-564.
2. Virtanen JK, Mursu J, Voutilainen S, Uusitupa M, Tuomainen TP. Serum omega-3 polyunsaturated fatty acids and risk of incident type 2 diabetes in men: the Kuopio Ischemic Heart Disease Risk Factor study. Diabetes Care. 2014;37(1):189-196.
3. Mosheer SM, Waldschutz W, Itanu BK, Brath H, Stulnig TM. A protein-enriched low glycemic index diet with omega-3 polunsaturated fatty acid supplementation exerts beneficial effects on metabolic control in type 2 diabetes. Prim Care Diabetes. 2014;8(4):308-314.
4. Estruch R, Ros E, Salas-Salvadó J, et al; PREDIMED Study Investigators. Primary prevention of cardiovascular disease with a Mediterranean diet supplemented with extra-virgin olive oil or nuts. N Engl J Med. 2018 Jun 21;378(25):e34.
5. Sala-Vila A, Díaz-López A, Valls-Pedret C, et al; Dieta Mediterránea (PREDIMED) Investigators. Dietary marine ω-3 fatty acids and incident sight-threatening retinopathy in middle-aged and older individuals with type 2 diabetes: prospective investigation from the PREDIMED Trial. JAMA Ophthalmol. 2016;134(10):1142-1149.
6. Connor KM, SanGiovanni JP, Lofqvist C, et al. Increased dietary intake of ω-3-polyunsaturated fatty acids reduces pathological retinal angiogenesis. Nat Med. 2007;13(7):868-873.
7. Nunes AC, Pontes JM, Rosa A, Gomes L, Carvalheiro M, Freitas D. Screening for pancreatic exocrine insufficiency in patients with diabetes mellitus. Am J Gastroenterol. 2003;98(12):2672-2675.
8. Dyerberg J, Madsen P, Møller JM, Aardestrup I, Schmidt EB. Bioavailability of marine n-3 fatty acid formulations. Prostaglandins Leukot Essent Fatty Acids. 2010;83(3):137-141.
9. Ewald N, Hardt PD. Alterations in exocrine pancreatic function in diabetes mellitus. Pancreapedia: Exocrine Pancreas Knowledge Base. 2015, Feb. 16. DOI: 10.3998/panc.2015.7. Available at: https://www.pancreapedia.org/reviews/alterations-in-exocrine-pancreatic-function-in-diabetes-mellitus . Accessed July 24, 2018.