Soaking does not help remove phytic acid, which interferes with the absorption of iron, calcium, zinc, and other minerals from nuts.
But this does not mean that eating nuts is pointless. They still have enough protein and other healthy substances.
Where did the idea to soak nuts come from?
Many fruits, vegetables, legumes, and whole grains contain antinutrients or antinutrients. This is the name of the chemical compounds necessary for the plant, for example, to protect against pests. But when humans eat these compounds, the antinutrients interfere with the absorption of vitamins and dietary minerals from plants.
All seeds, including legumes, grains, and nuts, contain an antinutrient called phytic acid. This substance contains phosphorus, which the future plant will need for growth.
When the nuts germinate, the phytase enzyme is activated: it breaks down phytic acid and makes the stored phosphorus available to the young plant. But in the human body, phytase is not produced, so we cannot absorb phosphorus from phytic acid.
In addition, phytic acid binds very easily to nuts’ calcium, iron, and zinc ions. But only free metal ions can be absorbed in the human intestine. It turns out that the presence of phytic acid reduces the number of dietary minerals we can absorb from nuts.
At the same time, phytic acid is highly soluble in water. And it can also be destroyed by phytase, activated during germination, and sometimes even when some seeds are soaked. Therefore, to reduce the phytic acid content of nuts, some health and nutrition bloggers advise soaking them in water for at least seven hours.
Most often, proponents of soaking nuts recommend dipping them in salted water. Allegedly, a small amount of salt activates phytase, which breaks down phytic acid, making phosphorus and minerals easier to absorb. After soaking, the nuts are suggested to be eaten immediately or dried in the oven for a day, so they do not become moldy during storage.
Can Soaking Nuts Get Rid of Phytic Acid?
Soaking works well for most legumes and grains. For example, soaking in hot water for eight hours reduces the level of phytic acid in legumes: in chickpeas – by 31-40%, in beans – by 25-32%. And if you leave sorghum in unsalted water at room temperature for 24 hours, the level of phytic acid is reduced by 16-21%.
It is difficult to explain such significant results by simple washing out – most likely, in these plants, phytase is activated during soaking, which breaks down most of the phytic acid.
For a long time, scientists believed that soaking affected nuts like legumes and cereals. But in 2020, researchers from New Zealand decided to check if this is the case.
They took almonds, hazelnuts, and walnuts and divided them into four portions. Nuts from the first and second portions were soaked in water with a salt content of 2%, only in the first case were they kept for four hours, and in the second – 12.
Nuts from the third portion were soaked in fresh water for 12 hours, and from the fourth portion, they were not soaked. The nuts, immersed in water, were dried in an oven for 24 hours. After that, in all nuts, including those with which nothing was done, the concentration of phytic acid was measured – and then it was estimated how much the content of free calcium, iron, and zinc increased in the almonds, hazelnuts, and walnuts used in the experiment.
The results showed that regardless of the time of soaking, the concentration of phytic acid in all nuts either did not change or changed very little. Adding salt to water did not affect the concentration of phytic acid either. This means that salt does not activate phytase in nuts. Most likely, in soaked portions, in which the amount of phytic acid in the end still decreased, it was partially washed out by water.
As for calcium, iron, and zinc ions, their concentration either did not increase or even slightly decreased in most soaked portions of nuts. This is most likely since soaking leaches out phytic acid and minerals.
As a result, the researchers concluded there was no point in messing with soaking nuts. And even more: soaking in salt water does not improve but worsens their nutritional quality.
An important advantage of fresh nuts is that they are tasty but contain very little salt. If you add these foods to your diet, it’s easier to stick to the recommendations that an adult should eat no more than five salt – that’s no more than 2.3 g of sodium per day. This helps reduce the risk of cardiovascular disease.
Before soaking, 100 g of almonds had only 0.8 mg of sodium. But after soaking in salt water, its concentration increased to 707 mg. A person who eats a thirty-gram handful of almonds soaked in salt water will receive almost 10% of the recommended daily sodium intake. That’s more than a slice of cheese pizza.
Should You Be Worried About Phytic Acid in Nuts?
If a person eats in a balanced way, he uses not only vegetables but also animal food; he has no reason to avoid nuts. Even if he does not receive enough dietary minerals from plant foods rich in phytic acid, there will be no deficiency since minerals are found in meat, milk, and eggs.
Can nuts be vegans? People who eat only plant-based foods can indeed become deficient in dietary minerals associated with an excess of phytic acid. But nuts remain an important source of vegetarian protein.
It is much easier to regulate the content of phytic acid in other plant foods – primarily in legumes, grains, cereals, and seeds. The phytic acid in most plant foods is reduced by almost any pre-treatment: soaking, sprouting, fermenting, and pickling. And since phytic acid is destroyed by boiling, boiling, and stewing will help reduce its level.
If you want to reduce the level of phytic acid in nuts, all methods will work except soaking. For example, nuts can be added to hot dishes or made into jam.
All of these treatments destroy antinutrients, increase soluble fiber, which is important for gut microflora, and generally make plant foods easier to digest.
How many nuts can you eat? All nuts are a good source of protein, fiber, and unsaturated fats that support heart and vascular health. At the same time, nuts are quite high in calories. For example, 100 g of pistachios provides 560 kcal. To avoid exceeding the calories, adults are recommended to eat no more than 4-6 servings of nuts per week. The serving size is approximately 30g.
How many nuts can children eat? Nuts can be given ground or in the form of a paste to children from the age of six months. To prevent a child from accidentally choking, whole nuts should not be given until five.
For the first time, it is better to offer nuts to children in small portions, literally 3-5 pieces each. After that, it is worth waiting a couple of days to understand if the child has allergies. If he feels normal, portions can be gradually increased. Children over five years old can eat the same nuts as adults.
Can nuts be pregnant and lactating? Yes, and even necessary. For the child to grow and develop well, women who received 2000 kcal daily before pregnancy need about 340 additional kilocalories per day in the second and 450 kilocalories in the third trimester of pregnancy. This is a couple of small snacks daily.
In this situation, a handful of nuts can help out. But some experts believe walnuts will be especially useful, as they contain the most omega-3 unsaturated fatty acids. According to some reports, these acids contribute to the development of the brain and nervous system of the fetus.
Lactating women, like pregnant women, need to get 450-500 extra kilocalories per day. Nuts can help with this too. But there is a caveat: in rare cases, substances from mother’s food, such as cow’s milk, soy, wheat, seafood, and nuts, can provoke allergic reactions.
If you have eaten nuts and fed the child, he begins to have hives; you need to discuss this with your doctor. The doctor will help you figure out what exactly is the matter and tell you how to avoid a similar problem in the future.