Nutrient Interactions

Vitamin C + Iron

Vitamin C helps your body absorb iron from plant foods.

Tip: Add peppers, citrus or tomatoes to meals built on beans, lentils or greens.

• Red Bell Pepper
• Orange
• Lentils
• Spinach

Vitamin D + Calcium

Vitamin D is needed to absorb calcium from the gut.

Tip: Low vitamin D limits how much calcium you take up, however much you eat.

• Salmon
• Sardines
• Milk
• Egg

Fat + Vitamins A, D, E & K

These four vitamins dissolve in fat, so a little fat in the meal helps you absorb them.

Tip: Dress salads with oil, roast carrots and sweet potatoes in a little oil, or add avocado.

• Carrot
• Sweet Potato
• Kale
• Olive Oil
• Avocado

Black Pepper + Turmeric

Piperine in black pepper substantially increases how much curcumin, turmeric’s key compound, is absorbed.

Tip: Cook turmeric with a pinch of black pepper and a little fat.

• Turmeric

Meat or Fish + Plant Iron

Eating meat, poultry or fish alongside beans or greens increases absorption of their plant (non-heme) iron.

Tip: Even a small amount of chicken or beef in a bean dish helps.

• Chicken Breast
• Sirloin Steak
• Black Beans
• Spinach

Magnesium + Vitamin D

The enzymes that turn vitamin D into its active form depend on magnesium.

Tip: If you take vitamin D, make sure your diet includes magnesium-rich nuts, seeds, beans and whole grains.

• Pumpkin Seeds
• Almonds
• Black Beans
• Salmon

Tomatoes + Cooking with Oil

Lycopene, the red pigment in tomatoes, is absorbed better from cooked tomatoes eaten with some fat.

Tip: Tomato sauce simmered with olive oil delivers more lycopene than raw tomatoes alone.

• Tomato
• Olive Oil

Folate + Vitamin B12

Folate and B12 work together to make DNA and healthy red blood cells.

Tip: High folic acid intake can mask a B12 deficiency, so get B12 checked if you avoid animal foods.

• Lentils
• Spinach
• Salmon
• Egg

Calcium + Iron

Calcium can cut iron absorption. Space them a couple of hours apart.

Tip: Take iron supplements away from dairy and calcium supplements.

• Milk
• Greek Yogurt
• Cheddar Cheese
• Lentils

Zinc + Copper

High-dose zinc over time can lead to low copper.

Tip: Long-term zinc supplements above about 40 mg a day are best discussed with a doctor.

• Oysters
• Cashews
• Pumpkin Seeds

Tea & Coffee + Iron

Tannins and polyphenols in tea and coffee reduce absorption of plant iron when drunk with meals.

Tip: If your iron is low, have tea or coffee an hour or so before or after eating.

• Green Tea
• Black Tea
• Coffee
• Lentils

Phytates + Iron, Zinc & Calcium

Phytates in whole grains, beans, nuts and seeds bind minerals and reduce how much you absorb.

Tip: Soaking, sprouting and fermenting (as in sourdough) break down much of the phytate.

• Oats
• Black Beans
• Whole Wheat Bread
• Almonds

Oxalates + Calcium

Oxalates in spinach and beets bind calcium, so very little of spinach’s calcium is absorbed.

Tip: Count dairy, fortified foods, kale and broccoli for calcium rather than spinach.

• Spinach
• Beets
• Kale
• Broccoli

Iron + Zinc

High-dose iron and zinc supplements taken together on an empty stomach reduce each other’s absorption.

Tip: Take separate supplements at different times, or with food, where the effect is small.

• Oysters
• Sirloin Steak
• Lentils

Alcohol + B Vitamins

Regular heavy drinking impairs absorption and use of thiamin (B1) and folate.

Tip: Heavy drinkers are at real risk of thiamin deficiency; it’s worth raising with a doctor.

• Pork Tenderloin
• Lentils
• Sunflower Seeds

Vitamin K + Warfarin

Vitamin K counteracts warfarin, so sudden changes in leafy greens can shift how well the medication works.

Tip: You don’t need to avoid greens. Keep the amount you eat steady from week to week.

• Kale
• Spinach
• Broccoli
• Brussels Sprouts

Grapefruit + Certain Medicines

Grapefruit blocks an enzyme that breaks down some medicines, including certain statins and blood-pressure drugs, raising their levels.

Tip: Check the label or ask a pharmacist; the effect can last a day or more after one glass.

Calcium, Iron & Magnesium + Some Medicines

These minerals can block absorption of thyroid medication and some antibiotics (tetracyclines and quinolones).

Tip: Space them apart; levothyroxine is usually taken about 4 hours away from calcium or iron.

• Milk
• Greek Yogurt
• Cheddar Cheese

Potassium + Some Blood-Pressure Medicines

ACE inhibitors, ARBs and potassium-sparing diuretics raise potassium, so salt substitutes or supplements can push it too high.

Tip: Potassium-based salt substitutes are the main concern; ask before using them.

• Banana
• Potato
• Avocado
• Coconut Water

Aged Cheese & Cured Meat + MAOIs

Tyramine in aged, cured and fermented foods can cause a dangerous spike in blood pressure with MAOI antidepressants.

Tip: Anyone on an MAOI should follow their prescriber’s food list closely.

• Parmesan
• Cheddar Cheese
• Bacon