20 September 2019
Nutrition is getting personal! As we uncover new technologies and learn more about our genes, we can work out what is healthiest to put on our plate. Because a one-size-fits-all approach isn’t necessarily the best. Tailoring diet and lifestyle advice and treatments to the individual may achieve better results than general advice.
Nutritional advice can be personalized in many ways. The current dietary guidelines are already broadly personalized. We wouldn’t expect a child to have the same nutrient requirements as an adult, or men to need the same as women. This is why nutrition authorities have formulated dietary advice based on age, gender and life stage. However, with the expansion in technologies on how we measure ourselves, our genes and our diet, we know more and more about what we need to keep us healthy and in top form. This means that we can tailor nutritional interventions to meet our health care needs.
Genes and Nutrition
The original concept of personalized nutrition was using knowledge of our genes to choose the best diet. Genes affect how we use nutrients and how our body reacts to them. For some medical conditions, genetics already determines the best diet to follow. A classic example is the disease phenylketonuria, caused by mutations in genes responsible for using the amino acid phenylalanine. If not discovered in infancy, permanent brain damage is caused by the build-up of phenylalanine in the blood. The condition is managed by diet: only foods low in phenylalanine may be consumed, and blood levels are controlled regularly (1).
Other genes have a more subtle effect on our nutrient needs. For example, vitamin B12 absorption relies on a protein called intrinsic factor, which is produced in the stomach. The quality of this protein and the amount produced depends on our genes (2). Normally, we produce enough to be able to absorb adequate B12 from our diet. However, small variations in the genes can mean that we absorb less vitamin B12 than we need. While not causing a frank deficiency, over time this can cause sub-clinical deficiency (3, 4), which has a range of symptoms such as general fatigue and heart palpitations (5). Dietary supplements can help support those with vitamin B12 deficiency. If people know their genotype, then it could help them avoid deficiency before symptoms develop.
Your Phenotype: What Does Your Body Tell You About What You Need to Eat?
Your phenotype is literally what can be “seen” about you: your height, weight and hair color are all examples. Other phenotypes are a little harder for us to “see” but can have a large impact on our diet. For example, some people are able to digest milk because their bodies produce the lactase enzyme in their small intestine, while others will not be able to digest it and experience unpleasant symptoms. The presence of the lactase enzyme can be considered a phenotype.
Advances in measurement technology are allowing us to look more closely at these different phenotypes. This allows us greater insight into the nutrient and health status of individuals. This can be seen in eye health. One factor in the development of age-related macular degeneration, a major cause of blindness in developed counties, is the amount of protective pigments in the eye. The pigments are only obtained from our diet: green leafy vegetables and brightly colored yellow and orange fruits are the main sources. However, the amount reaching our eye depends on more than just our diet. What we eat with the meal and genetics also play an important role in the amount of pigments that reach the eye. Luckily, we can measure the amount of pigments in the eye using a non-invasive technique (6). Together with information on normal intakes of the protective pigments, the measurements allow us to work out whether the amount of protective pigments is normal, and whether we will be able to increase the amount with dietary changes or a supplement. We will be able to personalize advice on keeping the eyes healthy with this simple test.
Metabotypes and How Your Body Reacts to Nutrients
Ever noticed how some people can seem to eat what they like and stay slim, while others have difficulty losing weight on a strict diet? Part of the difference is due to how people metabolize nutrients. This concept lies behind a “metabotype.”
In the medical field, finding out a patient’s metabotype can help choose the best diet and lifestyle for people who have recently developed type 2 diabetes. Type 2 diabetes is a chronic disease that occurs when the body does not produce enough insulin to bring down glucose levels after a meal. Glucose can either shoot up to very high levels after a meal, or it can remain at a high level around the clock, or both.
Diabetics with muscle insulin resistance are better off with a diet containing foods high in monounsaturated fatty acids (such as olive oil)and moderate protein and carbohydrates. Regular exercise will help their muscles react better to insulin. Monounsaturated fatty acids help to improve the way the body reacts to insulin (7). Diabetics with liver insulin resistance may do better with a low fat, high fiber diet with a higher protein content. The lower fat content and higher fiber will help the liver to lose its fatty deposits (7).
If we know someone’s metabotype, we can help them choose more effective lifestyle changes to help support an adjusted diet to support their diagnosis.
What Will Personalized Nutrition Look Like in Future?
The future of personalized nutrition will take our visit to the dietitian to the next level! First of all, we will be given an advanced dietary assessment to look at our normal diet and work out what we are getting from our food and supplements. Then, a blood sample will be sent off to be analyzed for many different things: genes, nutrient status, health parameters and disease markers. Then, we will be given a medical assessment and physical check. We may be able to integrate other tests such as a microbiome analysis or eye test into the assessment. The next step is to combine these different measurements together to provide a truly personalized assessment of our nutritional status. To finish, we will receive a series of recommendations tailored to our unique dietary needs, genes and health status.
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