Anti-nutrients an important part of a balanced diet

Anti-nutrients occur naturally in a number of healthy foods, including legumes and whole grains.PHOTO: GETTY IMAGES

Maybe you’re trying to eat healthier these days, aiming to get enough of the good stuff and limit the less-good stuff. You’re paying attention to things like fibre and fat and vitamins ... and anti-nutrients?

Anti-nutrients aren’t the evil nemesis of all the nutritious foods you eat. As long as you’re consuming a balanced and varied diet, anti-nutrients are not a concern. In fact, scientists are realising they actually have many health benefits.

What are anti-nutrients?

Anti-nutrients are substances that naturally occur in plant and animal foods.

The name comes from how they function in your body once you eat them. They block or interfere with how your body absorbs other nutrients. Thus, anti-nutrients may decrease the amount of nutrients you actually get from your food. They most commonly interfere with the absorption of calcium, iron, potassium, magnesium and zinc.

Plants evolved these compounds as a defensive mechanism against insects, parasites, bacteria and fungi. For example, some anti-nutrients can cause a food to taste bitter so animals won’t want to eat it. Some block the digestion of seeds so that when they come out the other end in the animal’s fecal matter they can go on to grow new plants. Both of these survival tactics help the plant species grow and spread.

In terms of foods that people eat, you’ll most commonly find anti-nutrients naturally occurring in whole grains and legumes.

Time for an image makeover

Despite sounding scary, studies show that anti-nutrients are not of concern unless consumed in ultra, unrealistically high amounts — and they have numerous health benefits.

Anti-nutrients are currently undergoing a change in image very similar to the one dietary fibre experienced. At one point, scientists thought dietary fibre was bad for people. Since fibre could bind to nutrients and pull them out of the digestive tract in poop, it seemed like something to avoid. To address this perceived issue, grain processing in the late 1800s removed fibre from foods.

But now scientists know that dietary fibre is important and encourage its consumption. Eating plenty of fibre lowers the risks of obesity, high blood pressure, heart disease, stroke, diabetes and some gastrointestinal diseases.

In the same way, rather than something to avoid, many anti-nutrients are now considered health-promoting nutraceuticals and functional foods due to their numerous benefits. Here’s some of the most frequently eaten anti-nutrients that come with benefits:

• Saponins, common in legumes, can boost the immune system, reduce risk of cancer, lower cholesterol, lower blood sugar response to foods, result in fewer cavities, reduce risk of kidney stones and combat blood clotting seen in heart attacks and strokes
• Lectins, found in cereal grains and legumes, are associated with reduced risk of cardiovascular disease, diabetes, some cancers and becoming overweight or obese
• Tannins, commonly found in teas, coffees and processed meats and cheeses, are antioxidants that can inhibit growth of bacteria, viruses, fungi and yeast and may decrease cholesterol levels and blood pressure
• Phytates, found in wheat, barley, rice and corn, are associated with increased immune function and cancer cell death, as well as reduced cancer cell growth and spread. They also have antioxidant properties and can reduce inflammation
• Finally, glucosinates, found in brassica vegetables like cauliflower, inhibit tumour cell growth

Oxalates are one of the few anti-nutrients with mostly negative impacts on the body. They are found in lots of common foods, including legumes, beets, berries, cranberries, oranges, chocolate, tofu, wheat bran, soda, coffee, tea, beer, dark green vegetables and sweet potatoes. The negative impacts of oxalates include binding to calcium in the digestive tract and removing it from the body in bowel movements. Oxalates can also increase the risk of kidney stones in some people.

Fitting anti-nutrients into a healthy diet

Overall, comparing the benefits to the drawbacks, anti-nutrient pros actually outweigh the cons. The healthy foods that contain them — mainly fruits, vegetables, whole grains and legumes — should be encouraged, not avoided.

A large proportion of anti-nutrients are removed or lost from food as they are processed and cooked, especially if soaking, blanching, boiling or other high-heat processes are involved.

Vegetarians and vegans may be at higher risk of negative effects from anti-nutrients because their diet relies on fruits, vegetables, whole grains and legumes. But these plant-based diets are still among the healthiest.

Vegetarians and vegans can take a few steps to help counteract anti-nutrients’ effects on their absorption of particular nutrients:

• Pair high iron and zinc foods with foods high in vitamin C (examples: vegetable meatballs with tomato sauce, tomato-based chilli with beans)
• Soak legumes before cooking
• Time dairy intake such that it is not always paired with high oxalate foods
• Purchase dairy products that are fortified with calcium
• Consider a multivitamin-mineral supplement with about 100% of the daily recommended dose of nutrients (check the nutrition facts panel) as nutrition insurance if you are worried, but be sure to talk to your doctor first.

— The Conversation

Jill Joyce is assistant prof of public health nutrition at Oklahoma State University.