Every couple has a way of working together — or not. It turns out that the principles that apply to human relationships also apply to food combinations. Some health-boosting nutrients work together with ease, while others are detrimental to one another. For example, did you know that if you add vitamin C-rich orange slices to a spinach salad, you'll absorb more iron than if you top the leafy greens with calcium-rich feta cheese? Don't worry: Learning which foods complement one another is not as difficult as it sounds. Remembering five basic pairings will go a long way toward maximizing your uptake of key nutrients from the foods you eat every day.
GOOD COMBO: Iron + vitamin C
Daily requirements: 10-20 mg iron; 1,000 mg vitamin C
No matter which foods you pair with meat, you absorb between 15 percent and 35 percent of the iron in meat (called heme iron). But if you're a vegetarian or eat primarily legumes and leafy greens, the bulk of your dietary iron is nonheme, which has an absorption rate of only 2 percent to 20 percent. Over time, inadequate absorption can lead to iron-deficiency anemia, a condition in which blood doesn't have enough healthy red blood cells to carry oxygen to tissues. Women are at particular risk for anemia; one in five women and half of all pregnant women are iron deficient.
To maximize your absorption of nonheme iron, add vitamin C-rich foods to your meal. Vitamin C (also called ascorbic acid) helps increase iron uptake by converting it into a more absorbable form or by preventing iron from binding to other elements during digestion, which renders nonheme iron unabsorbable.
- YES: Iron-fortified whole-grain cereal topped with soy milk and strawberry slices, plus a glass of orange juice on the side
- YES: Spinach salad with (chopped) red bell pepper and kiwifruit slivers
- YES: Tofu and broccoli with peanut sauce
GOOD COMBO: Beta-carotene + fat
Daily requirement: 3-6 mg beta-carotene (equivalent to 833-1,667 IU vitamin A)
Certain healthy compounds — particularly heart-protective and cancer-fighting beta-carotene and other carotenoids like lycopene and lutein — in fruits and vegetables are fat soluble. That means a bit of healthy fat needs to be around in the digestive tract to help the body absorb the nutrients. “Adding fats to those foods allows for better absorption and bioavailability,” says Paula Mendelsohn, RD, CCN, a functional medicine nutritionist in Boca Raton, Florida. Recent research backs up this claim: Adding avocado to salsas and topping salads with full-fat dressing boosts carotenoid absorption compared with avocado-free salsa and fat-free or reduced-fat salad dressing.
- YES: Cooked carrots drizzled with olive oil
- YES: Winter-squash soup sprinkled with chopped walnuts
- YES: Oatmeal topped with sliced almonds and mango chunks
BAD COMBO: Calcium + iron
Daily requirements: 10-20 mg iron; 1,000 mg calcium
“When both calcium and iron are present at the same time or in similar concentrations, they compete to be picked up, transported, and absorbed,” says Mendelsohn. In an effort to maximize supply of these critical nutrients, people often load up on them and pair them together. Take what seem like natural fits: fortified cereal and milk, yogurt and granola, goat cheese and spinach salad, or a sandwich with deli meat and cheese. The iron-rich cereal, leafy greens, and meat battle the calcium-rich dairy for the body's attention. “But it becomes an issue only if the person is eating whole-grain cereal solely for its iron content and not for the fiber and other nutrients it contains,” Mendelsohn explains.
- NO: Oatmeal topped with cow’s milk and chopped almonds
- NO: Steak with a side of creamed spinach
- NO: Lentil-broccoli salad topped with cucumber-yogurt sauce
- YES: Iron-fortified cereal sprinkled with raisins or dried apricots and unfortified soymilk, plus orange juice (for iron)
- YES: Plain bagel with cream cheese and fruit-filled yogurt (for calcium)
- YES: Roasted chicken with a side of seared asparagus and strawberry slices (for iron)
- YES: Apple pie with frozen yogurt (for calcium)
BAD COMBO: Iron + tea polyphenols
Daily requirement: 10-20 mg iron
New research shows that polyphenols in green tea block iron absorption by binding with the mineral to form a dense complex that can't be transported across intestinal cell membranes into the blood. According to Okhee Han, PhD, assistant professor at Pennsylvania State University and key author of the 2008 study, black tea also thwarts iron absorption: The high levels of tannic acid form an insoluble bond with iron in the gut, making iron indigestible. White tea has not yet been studied for its effects on iron.
And coffee drinkers aren't off the hook either: “Coffee also contains similar compounds that can prevent iron absorption,” says Robert Rountree, MD, Delicious Living's medical editor and coauthor of The New Breastfeeding Diet Plan (McGraw-Hill, 2007). “Coffee and tea consumption are major causes of iron-deficiency anemia in cultures around the world, especially in pregnant women,” he says. It's worth noting that these drinks mainly affect nonheme iron synthesis; iron in meat may be able to overcome the problem. It may be possible to avoid the polyphenol-iron conflict if you drink tea at a different time of day than when you eat iron-rich foods, says Han.
- NO: Black or green tea with iron-fortified cereal
- NO: Tofu scramble, plus black or green tea
- NO: Coffee alongside whole-wheat toast with almond butter
- YES: Oatmeal for breakfast and chai tea at mid-morning
- YES: Green tea upon waking up and green salad topped with baked tofu for lunch
- YES: Scrambled eggs and avocado wrapped in a whole-wheat tortilla in the morning and black tea in the early afternoon
BAD COMBO: Zinc + phytates
Daily requirement: 8-15 mg zinc
Phytates, found mostly in whole grains, nuts, and beans and legumes, bind with zinc, forming an insoluble complex that decreases your body's ability to absorb the immunity-boosting and wound-healing mineral. Beyond its role in immune function and tissue repair, zinc helps maintain your sense of taste and smell and stimulates numerous biochemical processes in the body. “Phytates adversely affect the absorption and retention of many minerals in the body, including zinc, calcium, magnesium, and iron,” says Melissa Diane Smith, a nutritionist in Tucson, Arizona, and author of Going Against the Grain (McGraw-Hill, 2002).
To counteract this result, eat your whole grains and beans apart from your zinc-rich red meat, poultry, and oysters. The zinc in whole grains and beans competes with the phytates in those very same plant foods, but there's some evidence that cooking (think baking wheat bread) may destroy phytates and thus help improve zinc absorption.
- NO: Multi-grain cereal and soymilk with a side of turkey sausage links
- NO: Beef-and-bean burrito on a whole-wheat tortilla
- NO: Lamb kabob with whole-wheat couscous and hummus
- YES: Pot roast with carrots, onions, and green beans
- YES: Broiled turkey burger with steamed broccoli and cauliflower medley
- YES: Large salad with assorted veggies, pieces of lamb, and pumpkin seeds
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