The first time I heard the term "personalized nutrition," I thought “That’s what registered dietitian/nutritionists are trained to do: develop the most appropriate eating plan for each individual person.” Sequencing the human genome has led to increased knowledge about the potential role individual genetic variations play in health and disease and is fueling the expansion of personalized nutrition.In today’s high-technology world, scientists are starting to envision being able to pinpoint accurate nutrition plans for each person based on their individual genetics, physical activity, sleep habits, microbiome (trillions of different species of microbes that are found primarily in our digestive tract and also spread throughout the body), and the metabolome (small molecules our body produces that may have specific effects on how our body functions). Currently nutrition recommendations are based on large epidemiological studies and are designed to apply to the majority of people. You’re familiar with many of them, such as: eat a minimum of 5 servings of fruit and vegetables per day, decrease the amount of red and processed meats we consume to reduce risk of cancer, consume less sodium to manage blood pressure. The dietary reference intakes (DRIs) on food labels are another example of recommendations designed for large population groups rather than individuals. Yet these recommendations do not help every person achieve improved health. You probably know someone who eats an extremely healthy diet yet develops heart disease, or perhaps someone who ignores every health guideline and lives to a healthy old age without chronic disease. It’s believed that personalized nutrition will provide specific, science-based recommendations for each individual person based on their own unique requirements.The International Society of Nutrigenetics/Nutrigenomics (ISNN) notes that our genetic profile, which is unique for each person, affects nutrient requirements, metabolism, and how our body responds to general nutrition recommendations. The ISSN describe personalized nutrition at three levels:

1. Conventional nutrition that uses general guidelines based on age, gender, and ethnicity such as the Dietary Guidelines for Healthy Americans.
2. Individualized nutrition that includes biochemical and metabolic information, cultural food preferences, and environmental and economic influences on food choices, which is the approach used by registered dietitian nutritionists.
3. The most recent approach, which is nutrition recommendations based on individual genotypes that impact the way foods are digested and nutrients are absorbed and utilized.

It’s well established that genetics play a major role in some situations, such as lactose intolerance, and new research is showing that genes may be an important factor in obesity, coronary artery disease, diabetes, and possibly even some types of cancer. It’s not just one single gene that has an impact on health, but rather a complex number of genes are involved in ways that are not yet completely understood.Personalized Nutrition Terminology and ApproachesNutrigenetics studies individual changes in weight, blood pressure, cholesterol, or blood glucose levels with different food choices and tries to correlate these to specific genes or gene variations.Foods and nutrients themselves are known to regulate gene activity. Nutrigenomics is the field of study that is working to understand more specifically how dietary factors influence gene expression and nutrient metabolism.A variety of different chemicals also can influence gene activity, which is known as epigenetics. Epigenetic modifications remain in our body as our cells divide, and sometimes can be passed down through subsequent generations. Environmental influences such as exposure to pollutants can impact epigenetic changes.Metabolomics is the scientific study of metabolites which are very small molecules produced within our body, and how they impact health and disease.There’s much interest in microbiomics, the study of the microbes in our digestive tract, and how food choices influence the health of the microbiome as well as how the microbiome itself impacts health.Should I have my DNA tested so that I know the best foods for me to eat based on my own genetic profile?In short – not yet. The hope is that by analyzing each person’s individual genetic profile, we will be able to identify with much more precision and certainty the most effective type of diet to prevent disease and promote health. However, a recent study showed that we have a long way to go before we can make gene-based food recommendations.A team of researchers from King's College in London and Harvard Medical School conducted the PREDICT study to figure out what factors determine each individual’s unique health-related response to food. The study included 700 identical twins and 400 non-twins and evaluated a number of responses to eating different types of food, such as changes in blood sugar and blood fat levels. The study confirmed that different people respond very differently to the same foods; however, it also showed that genetics account for less than one-third of the responses to food. While genes play a role, other factors such as sleep habits, exercise, stress, and microbes present in the gut play a much more important role than genes.The research team is in the process of enrolling more than 1000 participants in a home-based follow-up study called PREDICT2, which will measure nutrition responses to food over a period of 11 days. If you’re interested in applying to participate, check out https://joinzoe.com/.Bottom line: Within the next few years, the field of personalized nutrition will continue to grow and become more specific based on additional research and new technology. Right now, however, our genetic profile isn’t the primary factor in how our body responds to different foods. Proven areas where your daily choices play an important role include:

• Prevent or manage high blood pressure using the DASH diet which is based on 9 servings of vegetables and fruit, non-fat or low-fat dairy products, limiting saturated fat and tropical oils (coconut, palm kernel and palm oil), and choosing less sugar-sweetened beverages and sodium.
• Prevent diabetes using research from the Diabetes Prevention Program (DPP) which recommends reducing calories and carbohydrate and increasing daily physical activity to 150 minutes per week to lose 5-7% of body weight.
• Work toward optimum sleep habits which impact mental and physical health, body weight, stress management, blood pressure, heart disease, kidney disease, diabetes, risk of stroke, and quality of life. Adults should aim for 7-8 hours of sleep every night.
• Incorporate physical activity into your daily routine to prevent diabetes, cardiovascular disease and cancer. The World Health Organization recommends a minimum of 150 minutes of moderate intensity physical activity each week; 300 minutes (about 40-45 minutes per day) provides even more benefits. Include strength training 2-3 times per week to further strengthen muscles and bones.
• Use the guidelines from Choose MyPlate which are based on the most recent Dietary Guidelines for Americans to reduce risk of diabetes, heart disease and cancer and promote a healthy microbiome: include plenty of fruit, vegetables, and whole grains in your daily food choices. Choose fat-free or low-fat dairy products and include seafood and plant-based sources of protein (legumes, nuts, seeds, nut butter, soy foods). Limit sodium, saturated fat, and added sugar.
• Manage stress to reduce the effects of chronic stress on digestive issues, headaches, poor digestion, sleep problems, weight gain, high blood pressure and stroke. Laughter, managing time, exercise, being outside, and activities such as yoga, tai chi, mindful breathing, or meditation are proven strategies to manage stress.

By Lynn Grieger, RDN, CDE, CPT, CHWC. Grieger has applied to participate in the PREDICT2 study.References:

1. Ordovas JM, Ferguson LR, Tai, ES, Mathers, JC. Personalized nutrition and health. BMJ 2018;361:bmj.k2173
2. International Food Information Council Foundation. Personalized Nutrition: Ready for Prime Time? Allison Webster, PhD, RD. https://foodinsight.org/personalized-nutrition-ready-for-prime-time published 1-16-18; accessed 12-4-19
3. Scientific American. Personalized Nutrition: The Latest on DNA Based Diets. Monica Reinagel. https://www.scientificamerican.com/article/personalized-nutrition-the-latest-on-dna-based-diets/ published 9-27-19; accessed 12-4-19.Zoe. Eat the way your body loves. https://joinzoe.com/ accessed 12-7-19
4. U.S. Department of Health and Human Services. National Heart, Lung and Blood Institute. DASH eating plan. https://www.nhlbi.nih.gov/health-topics/dash-eating-plan accessed 12-9-19.
5. Centers for Disease Control and Prevention. National Diabetes Prevention Program. Research Behind the National DPP. https://www.cdc.gov/diabetes/prevention/research-behind-ndpp.htm last reviewed 4-4-19; accessed 12-9-19.
6. U.S. Department of Health and Human Services. National Heart, Lung and Blood Institute. Sleep Deprivation and Deficiency. https://www.nhlbi.nih.gov/health-topics/sleep-deprivation-and-deficiency accessed 12-9-19.
7. World Health Organization. Physical Activity. https://www.who.int/news-room/fact-sheets/detail/physical-activity published 2-23-18; accessed 12-9-19.
8. Choose MyPlate. Start Simple with MyPlate. https://www.choosemyplate.gov/eathealthy/start-simple-myplate accessed 12-9-19.
9. American Heart Association. Lower Stress: How Does Stress Affect the Body? https://www.heart.org/en/healthy-living/healthy-lifestyle/stress-management/lower-stress-how-does-stress-affect-the-body published 7-17; accessed 12-9-19.