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Food Pairings to Optimize Nutrition by Christina Badaracco, MPH, RD

Did you know that eating certain foods together can create a synergy that enhances the function of one or more of the nutrients in those foods? Different vitamins, minerals and antioxidants can affect the absorption, bioavailability and activity of one another. Your healthcare provider likely guides you regarding combinations of medications to take (or not take) together to maximize their effectiveness and minimize adverse side effects. Similarly, guidance about cooking and eating certain nutrients together is important to optimize their functions and potential health benefits. Six examples of such synergies and examples of relevant food combinations are described below.


1. Lycopene and olive oil

Lycopene is a plant compound in the carotenoid family that gives many fruits and vegetables their red and pink colors. The top sources of lycopene include tomatoes, watermelon and guava. Because carotenoids are fat-soluble, eating them with a source of fat increases their absorption. Lycopene acts as an antioxidant in the body, preventing oxidative damage. Its consumption is associated with improved lipid profiles, protection against UV damage, reduced risk of stroke and other benefits. Olive oil is likely the best choice of fat to consume with lycopene, as evidence suggests that the combination leads to higher antioxidant activity. Many studies also suggest that cooking tomatoes (which can, of course, be done with olive oil) makes the lycopene more bioavailable.


Examples of food combinations include:

  • Tomato sauce (lycopene) cooked in olive oil

  • Watermelon (lycopene), feta and mint in an olive oil-based dressing

  • Sun-dried tomato (lycopene) pesto made with olive oil

2. Non-heme iron and vitamin C

Iron is essential for many physiological functions, such as helping to produce red blood cells and oxygenate the blood, supporting immune responses and aiding cognitive function. Dietary iron exists in two forms: heme, found in some animal foods, and non-heme, found in animal and plant foods. Most of our intake comes from non-heme iron in fortified grains, legumes, leafy green vegetables and meats. Non-heme iron is less bioavailable than heme iron, but consuming a source of vitamin C (or ascorbic acid) with it can enhance absorption. Vitamin C modifies the non-heme iron molecule to increase absorption from the gastrointestinal tract and mobilization from storage forms in the body. To maximize this effect, it's best to consume it at the same time as the iron.


Examples of food combinations include:

  • Smoothie with spinach (iron) and pineapple (vitamin C)

  • Stir-fry with bell peppers (vitamin C), tofu (iron), mushrooms, onions and brown rice

  • Chickpeas (iron) with lemon (vitamin C) tahini dressing

3. Curcumin, piperine and fat

A member of the ginger family, turmeric has been commonly eaten as a spice and used medicinally for millennia. It is generated from the plant's rhizome (or subterranean stem) and contains multiple health-promoting compounds, the most common of which is a polyphenol called curcumin. Both whole turmeric and isolated curcumin are known to have myriad health benefits, ranging from reducing inflammation to preventing cancer formation/progression to improving insulin sensitivity. Its low bioavailability has prompted researchers to investigate ways to enhance its absorption and utilization by the body; one method is to pair it with piperine, the compound in black pepper that imparts its pungency. Piperine has been shown to increase the absorption and activity of turmeric and curcumin by up to 2,000% (thereby substantially increasing its potential health benefits). Thankfully, these spices are commonly paired together in recipes. Also, like lycopene, curcumin is fat-soluble, so its absorption is enhanced when consumed with fat.


Examples of food combinations include:

  • Coconut (fat) curry (curcumin and piperine in spices) salmon (fat) and vegetables

  • Golden (curcumin and piperine in spices) milk (fat in milk)

  • Salad with lemon turmeric (curcumin) dressing (fat in olive oil) and black pepper (piperine)

4. Vitamin C and catechins

Plants produce many types of secondary metabolites, which are compounds that are not necessary for metabolism but play a protective role in the plant. They also typically exhibit strong antioxidant activity when consumed by humans. Catechins are one such group; their proven benefits include protecting against tumor formation, promoting lipid metabolism, enhancing glucose sensitivity and more. While there are many different forms of catechins, the most well-known is epigallocatechin gallate (EGCG), found in green tea. They are also found in berries, chocolate, wine, stone fruit and beans. Studies have shown that combining different nutrients with foods that contain these catechins can enhance their absorption and stability after digestion; one of these nutrients is vitamin C (which also happens to be an antioxidant).


Examples of food combinations include:

  • Dark chocolate (catechins) with strawberries (vitamin C)

  • Smoothie with cherries (catechins), oranges (vitamin C) and almond butter

  • Sangria (catechins in wine, vitamin C in orange juice) with berries (catechins)

5. Fat-soluble vitamins with dietary fat

Vitamins A, D, E and K are fat-soluble, meaning they are absorbed by the body together with fat. Some of the common food sources for these vitamins are as follows:

  • Vitamin A: fatty fish, liver, dairy, fortified grains

  • Vitamin D: fatty fish, egg yolks, fortified dairy

  • Vitamin E: seeds, nuts, oils, avocado

  • Vitamin K: leafy green vegetables (K1); liver and fermented foods (K2)

Consuming fat-soluble vitamins with fat (or better yet, a full meal with adequate fat [i.e., at least 15 grams]) can help to maximize the absorption of both food- and supplement-based forms of these vitamins and their resulting blood concentrations.


Examples of food combinations include:

  • Green beans (vitamin K) sautéed in olive oil (vitamin E, fat)

  • Thai salad with cucumbers (vitamin K) and peanut dressing (vitamin E, fat)

  • Low- or full-fat (fat) yogurt made with fortified milk (vitamins A and D)

6. Mustard seed and cooked cruciferous vegetables

Cruciferous vegetables are among the most nutrient-dense vegetables, providing rich sources of vitamin K, fiber, potassium, antioxidants and more. Common examples include broccoli, cauliflower, mustard greens, turnips and arugula. The well-studied glucosinolate metabolites found primarily in cruciferous vegetables have been shown to offer many benefits. An enzyme called myrosinase converts them into other compounds (e.g., sulforaphane and other isothiocyanates; see equation below) that benefit our bodies. Cooking, however, prevents this process. As noted in an earlier SOULFUL Insight about cruciferous vegetables, our gut bacteria can produce myrosinase, helping to maximize the conversion of glucosinolates. Also, it's been suggested that adding a source of myrosinase from an uncooked crucifer (such as mustard seeds or powder) can augment the myrosinase in a dish to increase the body's conversion of glucosinolates into beneficial metabolites.

Examples of food combinations include:

  • Aloo gobi, or Indian cauliflower (glucosinolates) and potatoes (myrosinase in mustard seeds)

  • Broccoli (glucosinolates) cheddar soup (myrosinase in mustard powder)

  • Sautéed, shredded Brussels sprouts (glucosinolates) with mustard seeds (myrosinase) and lemon

Additional considerations

Some nutrients should not be eaten together as some of their nutritional value is lost when they're combined. Examples include:

  • Copper, iron and zinc can compete with one another for absorption (which is especially important to consider when taken in supplement form and at higher doses)

  • Iron has also been shown to impair the activity of some antioxidants; they, in turn, can also impair iron absorption, so consider avoiding drinks like green tea and wine when consuming iron-rich foods (especially if you are anemic)

  • Oxalic acid is a compound that can impair calcium's absorption; these two nutrients are commonly found together in foods like spinach and beans, so such foods can't be expected to provide great sources of calcium

Finally, some media figures and nutritionists have recommended avoiding certain food combinations; examples include not consuming protein with carbohydrates and only eating fruit on an empty stomach. These recommendations are not grounded in evidence from clinical studies or decades of epidemiological research and don't reflect recommendations for overall healthy dietary patterns. Instead, consider the synergies described above and ways that you can incorporate more of those pairings into your meals each day.


Resources

Christina Badaracco, MPH, RD

Christina is a registered dietitian and author who aims to improve access to healthy and sustainable food and educate Americans about the connections between food and health. She loves to experiment with healthy recipes in the kitchen and share her creations to inspire others to cook.


Christina completed her dietetic internship at Massachusetts General Hospital and earned her Master of Public Health degree from the University of California, Berkeley. Previously, she graduated with a degree in Ecology and Evolutionary Biology from Princeton University, after conducting her thesis on sustainable agriculture and energy in Kenya. She has done clinical nutrition research at the National Institutes of Health, menu planning and nutrition education at the Oakland Unified School District and communications at the Environmental Protection Agency's Office of Water. She has also enjoyed contributing to children’s gardens, farmers markets and a number of organic farms.


cbadarac@gmail.com

www.linkedin.com/in/christina-badaracco/

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