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27-11-2025

Nutrient Combinations & Functional Nutrition: How to Enhance Absorption in Practice

In today’s age of abundant information on nutrition, more of us are making increasingly conscious choices on our plates. However, a crucial dimension of nourishment often remains overlooked: it is not enough to consume nutrient-dense foods; we must also absorb them properly. Our gut is a sophisticated, selective system that communicates continuously with the needs of our metabolism. Even foods of the highest quality may offer minimal benefit to the body if proper food combinations, a functional intestinal lining, or optimal digestive conditions do not support their nutrients.

Low blood levels of iron, ferritin, or vitamin D are common in laboratory tests, even in individuals with seemingly balanced diets. Chronic fatigue, brittle nails, or low mood are also frequent, despite the intake of appropriate nutritional supplements. In such cases, the conventional approach is often insufficient. Functional Medicine investigates the “why” behind insufficient nourishment, focusing on underlying dysfunctions that affect nutrient absorption and nutrient bioavailability.

Comprehensive and functional prevention is not only about “good” nutrition; it is grounded in an understanding of the mechanisms through which the body operates. Based on these mechanisms and simple functional practices, we can enhance the absorption of the nutrients we already consume. In doing so, we achieve a truly balanced and efficient nutritional profile. At the same time, it is essential to recognize when absorption dysfunctions warrant further investigation through specialized laboratory testing.

Eating well but not benefiting? Where nutrients get lost

Nutrient absorption is not a passive process. It requires the effective coordination of digestion mechanisms, intestinal permeability, and the activity of specialized cellular transporters. Most micronutrients (e.g., vitamins, minerals, trace elements, and fatty acids) are not immediately bioavailable. They must first be released from their food matrix through enzymatic and chemical digestion before crossing the intestinal epithelium into systemic circulation. Only then can they reach target tissues and exert their biological functions. Several dietary factors can impair effective nutrient absorption. Characteristic examples include:

  • The presence of phytic acid (phytates), found mainly in whole grains, legumes, and seeds, can inhibit the absorption of key minerals, including iron, calcium, and zinc. Phytates form stable complexes with these mineral ions in the intestinal lumen, which are not absorbable through the epithelium and are ultimately excreted. This effect is more pronounced when plant-based foods are consumed without prior processing methods that reduce phytate content, such as soaking or fermentation.
  • Vitamin C (ascorbic acid), by contrast, can significantly enhance the absorption of non-heme iron (iron of plant origin). It acts as a reducing agent, converting ferric (Fe³⁺) to ferrous (Fe²⁺) iron, the form more readily absorbed by intestinal transporters. Moreover, it prevents the formation of insoluble iron-phytate complexes, further improving iron bioavailability in vegetarian meals.
  • The absorption of fat-soluble vitamins A, D, E, and K requires the concurrent presence of dietary fat in the same meal. Fats stimulate the secretion of bile and pancreatic enzymes, which are necessary for the transport of these vitamins across the intestinal lining. Without effective emulsification and transport, these vitamins are not absorbed and are excreted instead. Thus, even foods rich in fat-soluble vitamins, such as carrots or spinach, offer minimal nutritional value when consumed without fat.
     

Beyond dietary factors, nutrient absorption may also be disrupted by endogenous biological limitations, such as reduced gastric acid secretion (hypochlorhydria), intestinal dysbiosis, or inflammation of the intestinal lining (as seen in leaky gut syndrome). In some individuals, genetic variations in enzymes or transport proteins may also play a role. Additionally, chronic use of antacids and sustained psychological stress can impair normal digestive function and, consequently, the body’s ability to effectively utilize nutrients.

Nutrient Combinations and Practical Tips for Improved Absorption

Within the framework of Functional Medicine, where nutrition is approached as a dynamic and interconnected biological system, food combinations are a critical, though not exclusive, link in the chain of optimal health. The combinations listed below are not theoretical suggestions; they are supported by scientific studies examining the absorption of vitamins, minerals, and antioxidants through the gastrointestinal tract. They are also accompanied by lifestyle advice to support intestinal and metabolic function. Here are some targeted, practical strategies you can immediately apply to your daily routine:

  1. Plant-based iron + Vitamin C: The absorption of iron from plant-based sources (such as lentils, spinach, and whole grains) increases significantly when a source of vitamin C is consumed in the same meal, such as orange, kiwi, or bell pepper. In contrast, calcium (from dairy or eggs) and tannins (from coffee or tea) can hinder iron uptake. Practical examples: Lentils with lemon, salad with bell peppers and black beans, oatmeal with seasonal fruits (orange in winter, kiwi in summer, or strawberries in spring).
  2. Vitamins or Carotenoids + Fats: Fat-soluble vitamins require the presence of dietary fat to cross the intestinal barrier into the bloodstream. If you consume salad without oil or steamed vegetables without accompaniment, a significant portion of these vitamins is lost. Similarly, lycopene from tomatoes, lutein from carrots, and other carotenoids are absorbed more efficiently when consumed with fats. Combining them with cold-pressed oils or natural fat sources increases their bioavailability. Practical examples: Olive oil over spinach, roasted vegetables with avocado, tomatoes with olive oil, carrots with hummus.
  3. Curcumin + Piperine: Curcumin, the active compound in turmeric, is poorly absorbed unless combined with piperine from black pepper, which can increase its bioavailability by up to 2000%. Practical example: Turmeric in soups or lentils, always paired with a pinch of black pepper.
  4. Nourishment in Sync: Digestion and nutrient absorption do not rely solely on what we eat but are enhanced when supportive environmental and physiological conditions are in place. Elements such as a regular circadian rhythm, restful sleep, exposure to natural light (especially for vitamin D synthesis and microbiome regulation), mindful chewing, and a calm atmosphere during meals all create a physiological environment that favors efficient digestion. Conversely, chronic stress and erratic habits can disrupt these processes and reduce nutrient uptake. Practical examples: Good-quality sleep, a regular circadian rhythm, sunlight exposure (especially for vitamin D and gut microbiome balance), mindful chewing and eating in a relaxed setting, and avoiding stressors that disrupt digestion.
  5. Gut Care: Effective nourishment requires a well-functioning intestinal lining, a balanced and diverse microbiome, and adequate secretion of digestive enzymes. When issues such as bloating, unstable weight, or food sensitivities are present, they may point to underlying inflammation or intestinal permeability ("leaky gut"). In such cases, even the most well-planned food combinations will yield minimal results. Practical example: Supporting the gut with prebiotics, probiotics, and personalized nutritional interventions.
When poor absorption is a sign that further investigation is needed

Deficiencies in certain micronutrients (such as iron or specific vitamins) are not uncommon. In fact, they affect many individuals even in the absence of diagnosed diseases. Underlying dysfunctions in nutrient absorption mechanisms can manifest through mild but persistent symptoms. Evidence warranting further laboratory investigation includes:

  • Fatigue, low energy, or “brain fog”
  • Brittle nails or hair loss
  • Digestive discomfort or bloating after meals
  • Increased susceptibility to infections
  • Mood fluctuations
     

Attempting to address these issues solely through dietary changes or supplements, without knowing the exact underlying problem, may lead to disappointment or even nutrient overdosing. Nutrient combinations are a valuable preventive tool. However, when malabsorption persists even in individuals following a “healthy” diet, it is time to explore functional causes and identify where exactly the absorption chain is breaking down.

Often, individuals experiencing deficiency-related symptoms may show normal test results on standard blood panels. In these cases, the Functional Medicine approach reveals subtle imbalances by offering specialized testing, such as:

Conclusion

Nutrition is not merely a matter of calories or nutrients—it is a complex process of cellular nourishment. Smart food combinations can significantly improve the absorption of key vitamins and minerals, but they represent only one piece of the puzzle. For the body to function correctly, we must understand what actually reaches the cells and why. Functional Medicine allows us to look beyond general guidelines and approach our health with precision and personalization. With the right guidance and proper laboratory testing, prevention becomes reality.

What you can do today:

  • Discover what’s truly happening in your body with the NutriScan® group of tests. This advanced functional panel offers a complete picture of your nutritional status by assessing key vitamins, minerals, trace elements, and antioxidants.
  • See how Functional Medicine can help you in practice, by identifying root causes instead of just masking symptoms.
  • Subscribe to our newsletter to be the first to receive updates on new preventive tests, wellness articles, and practical advice from Diagnostiki Athinon.
References
  1. Liu X, Zeng T, Zhang E, et al. (2025) Plant-based bioactives and oxidative stress in reproduction: anti-inflammatory and metabolic protection mechanisms. Front Nutr. 2025;12:1650347.
  2. Parveen, B., Rajinikanth, V. & Narayanan, M. (2025) Natural plant antioxidants for food preservation and emerging trends in nutraceutical applications. Discov Appl Sc 7, 845.
  3. Reboul E.(2015) Absorption of vitamin A and carotenoids by the enterocyte: focus on transport proteins. Nutrients. 2013;5(9):3563-3581.
  4. Petroski W, Minich DM. (2020) Is There Such a Thing as "Anti-Nutrients"? A Narrative Review of Perceived Problematic Plant Compounds. Nutrients. 2020;12(10):2929.
  5. De Zan D, Eletti F, Fiore G, et al. (2025) Use of Nutritional Strategies, Bioactive Compounds, and Dietary Supplements in Young Athletes: From Evidence to Potential Risks-A Narrative Review. Nutrients. 2025;17(13):2194.

At Diagnostiki Athinon, we take prevention seriously. This is where science meets personalized care.

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