BACKGROUND: A recent systematic review, which used the GRADE methodology, concluded that there is strong evidence for two gene-diet associations related to omega-3 and plasma triglyceride (TG) responses. Systematic reviews can be used to inform the development of clinical practice guidelines (CPGs).
OBJECTIVE: To provide guidance for clinical practice related to genetic testing for evaluating responsiveness to dietary/supplemental omega-3s and their impact on plasma lipids/lipoproteins/apolipoproteins.
METHODS: Using the results of the abovementioned systematic review, the first CPGs in nutrigenetics were developed using the established GRADE methodology and AGREE II approach.
RESULTS: Three clinical practice recommendations were developed. Most gene-diet associations identified in the literature lack adequate scientific and clinical validity to warrant consideration for implementing in a practice setting. However, two gene-diet associations with strong evidence (GRADE quality: moderate and high) can be considered for implementation into clinical practice in certain cases: male APOE-E4 carriers (rs429358, rs7412) and TG changes in response to the omega-3 fatty acids eicosapentaenoic acid (EPA) and/or docosahexaenoic acid (DHA) as well as a 31-SNP nutrigenetic risk score and TG changes in response to EPA+DHA among adults with overweight/obesity. Ethical and regulatory implications must be considered when providing APOE nutrigenetic tests given the well-established link between APOE genetic variation and Alzheimer\'s Disease.
CONCLUSIONS: Most of the evidence in this area is not ready for implementation into clinical practice primarily due to low scientific validity (low quality of evidence). However, the first CPGs in nutrigenetics have been developed for two nutrigenetic associations with strong scientific validity, related to dietary/supplemental omega-3 and TG responses.

Omega-3 polyunsaturated fatty acids (n-3 PUFAs) are recommended as an integrative treatment for major depressive disorder (MDD). In 2019, the International Society for Nutritional Psychiatry Research (ISNPR) developed the first practice guidelines for n-3 PUFA treatment of MDD. To strengthen these guidelines and enhance their clinical applicability, we synthesized the evidence and clinical experiences previously obtained through the Delphi methodology.
Nineteen statements covering five major domains in MDD treatment were formulated through internal meetings. Fourteen international experts were invited to participate in the web-based Delphi process that validated the statements. Likert scales were used, and consensus level was set at 7.0/10.0, with the equivocal level set at 5.1-6.9. The items with scores < 5.0 were allocated into a second round Delphi survey with inverse questions.
All panelists completed the survey. Sixteen statements reached consensus, and the statement \"n-3 PUFAs are one of the potential adjunctive treatments for adult MDD\" reached the highest agreement. \"N-3 PUFAs are one of the potential monotherapies for adult MDD\" instead scored lowest. Regarding \"special populations,\" many items, reached high consensus despite sub-optimal supportive evidence.
The panelists had a specialized interest in n-3 PUFAs; focus was placed on clinical issues rather than on biological mechanisms.
The Delphi process helps bridge the gap between scientific evidence and clinical practice, supports certain uses of PUFA and identifies insufficiency in current evidence that merit future research.

The importance of lifestyle and dietary habits during pregnancy and breastfeeding, for health of mothers and their offspring, is widely supported by the most recent scientific literature. The consumption of a varied and balanced diet from the preconceptional period is essential to ensure both maternal well-being and pregnancy outcomes. However, the risk of inadequate intakes of specific micronutrients in pregnancy and lactation is high even in the most industrialized countries. This particularly applies to docosahexaenoic acid (DHA), iron, iodine, calcium, folic acid, and vitamin D, also in the Italian population. Moreover, the risk of not reaching the adequate nutrient supply is increased for selected groups of women of childbearing age: those following exclusion diets, underweight or overweight/obese, smokers, adolescents, mothers who have had multiple or close pregnancies, and those with previous unfavorable pregnancy outcomes.