Changing our current diet to a plant-based one is good for the environment as well as our own bodies, especially if we want to eat cleaner for physical health and/or get leaner. In general, daily meals that consist of vegetables, pulses, and fruit have a relatively low climate impact.
Therefore, we’ve often found meat alternatives made from plants, available for those who still want to enjoy texture and taste like real meat. Unfortunately, there’ve been only a few studies of how such products affect human health.
In a new study from Chalmers University of Technology, a research team in the Division of Food and Nutrition Science analyzed 44 different meat substitutes sold in Sweden. Mostly, the products include plant ingredients such as soy and pea protein, fermented soy like tempeh, and mycoproteins (proteins from fungi).
Lead author Cecilia Mayer Labba said, “Among these products, we saw a wide variation in nutritional content and how sustainable they can be from a health perspective.
“In general, the estimated absorption of iron and zinc from the products was extremely low. This is because these meat substitutes contained high levels of phytates, antinutrients that inhibit the absorption of minerals in the body.”
Nutritional limitations from plant-based protein
Phytates, a substance found naturally in beans and cereals, accumulate when the making of meat substitutes need protein extraction. In the gastrointestinal tract, where mineral absorption takes place, phytates form insoluble compounds with essential dietary minerals, especially non-heme iron (iron found in plant foods) and zinc.
In laymen terms, our bodies can’t absorb them in the intestine.
Labba said, “Both iron and zinc also accumulate in protein extraction. This is why high levels are listed among the product’s ingredients, but the minerals are bound to phytates and cannot be absorbed and used by the body.”
According to the study, 10 to 32% of women of childbearing and almost one in three teenage girls at secondary school in Sweden age suffer from iron deficiency.
Furthermore, women are most likely to have switched to a plant-based diet and to eat the least amount of red meat, which is the main source of iron that can be easily absorbed in the digestive tract.
Co-author Ann-Sofie Sandberg added, “When it comes to minerals in meat substitutes, the amount that is available for absorption by the body is a very important consideration. You cannot just look at the list of ingredients.
“Some of the products we studied are fortified with iron, but it is still inhibited by phytates. We believe that making nutrition claims on only those nutrients that can be absorbed by the body could create incentives for the industry to improve those products.”
A similar study
Previous research done by American Chemical Society (ACS) is in accord with the Chalmers one in terms of how plant-based diet nutrient that makes into human cells isn’t well-studied.
The study reported that proteins in a model plant-based substitute were not as accessible to cells as those from meat. Even though consumers believe that these products are healthier due to the high amount of protein and low amount of undesirable fats, the lab tests proved otherwise.
ACS researchers found that proteins in substitutes don’t break down into peptides as well as those from meats. The team took it a step further by creating a model meat alternative made of soy and wheat gluten with the extrusion process and compared it to a piece of chicken.
When the researchers cut them, the meat substitute had long fibrous pieces inside, just like chicken. Then they break down and grind up both materials with an enzyme that humans use to digest food.
In vitro tests showed that meat-substitute peptides were less water-soluble than those from chicken, and they also were not absorbed as well by human cells.
The team concluded that further research is needed to identify other ingredients that could help boost the peptide uptake of plant-based meat substitutes.
Plant-based proteins need an update
The studies don’t mean to say that meat substitutes are bad, and we should just stop eating them; they simply show that current alternatives are not good enough for our body and therefore need improvement.
For instance, the fermented soybeans tempeh isn’t the same as other meat substitutes in the amount of iron available for absorption by the body. The reason being fermentation of tempeh uses microorganisms that break down phytates.
Mycoproteins stood out for their high zinc content, without containing any known absorption inhibitors. Per the Chalmer researchers, however, it is still unclear how well our intestines can break down the cell walls of mycoprotein and how this in turn affects the absorption of nutrients.
“Plant-based food is important for the transition to sustainable food production, and there is huge development potential for plant-based meat substitutes,” Labba said.
“The industry needs to think about the nutritional value of these products and to utilize and optimize known process techniques such as fermentation, but also develop new methods to increase the absorption of various important nutrients.”
Other than this discovery, the Chalmers team found that the nutritional value of meat substitutes available today is often deficient depending on the choice of raw material and processing conditions, as well as on additives such as fat quality and salt.
The researchers also discovered that a meal containing 150 grams (about 5.29 oz) of meat substitutes contributes up to 60% of the maximum recommended daily intake of salt, which according to the Nordic Nutrition Recommendations is 6 grams.
Simply put, meat substitutes need further development so that soon, people with plant-based diet can incorporate “meat” in their daily meals without the lack of nutrients.
Reduce meat alternatives, more veggies, more supplements
So for now, while we’re waiting for updated versions of meat substitutes and still maintain a plant-based diet, what we can do is rely on supplements.
For iron, there are a lot of brands on the shelves that sell them in the form of caplets or pills. Like many other important nutrients mentioned after this, it’s important to consult your physician as to how many you should take in a day so that your body will have enough of them.
Apart from iron, vitamin B12 is something that’s scarcely available in plants despite being an essential nutrient for our body (maintaining nerves and normal brain function).
Studies have reported that people who adopt exclusive plant-based diet that take no supplements are at a high risk of vitamin B12 deficiency. It’s a different case for lacto-ovo-vegetarians because they still get adequate amounts of B12 from dairy products and eggs.
People might argue that nori seaweed is a great alternative, because it’s considered the most suitable source of biologically available vitamin B12. However, it doesn’t give our body enough amount on its own, not to mention the high amount of sodium and fat found in conventional nori seaweed products.
Creatine and carnosine play important roles in muscle function and brain; both are bioactive compounds also rarely found in plant-based diets. For people who need carnosine intake, beta-alanine supplements can help increase the levels of carnosine in muscles.
Finally, one of the many other nutrients not found in plants but are important to our body that I can’t all mention is good old vitamin D3.
I know, I know, you can get it from the sun. But, we rarely get the sun during winter months (for those who regularly experience dark, cold winters). If you don’t want to get this vitamin from fatty fish, egg yolks, or milk, your best bet is supplements.
But hey, if you have the sun available, just go out in the sun and enjoy it!
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