Tofu 101: The Benefits and Potential Risks of Eating Tofu

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Tofu is a substance that has been marketed as a meat-substitute and is a great source of B vitamins and a versatile foodstuff for those who are on a plant-based diet. It is made out of fermenting soy “milk”, which is then pressed into a cube shape. The density of the tofu can be changed based on the level of compression involved. Tofu has been a part of Eastern Asian cuisine for thousands of years and has been closely linked to the spread of cultural vegetarianism throughout the area. This article will discuss the health benefits and risks associated with the product, including comparisons to meat and plant products, and the overall efficacy as a dietary staple.

For the sake of this article, we will be using the statistics prepared and published by the USDA on firm, silken tofu [1] as this is one of the most common varieties and has the middling properties of both soft-silken and firm tofu.

Calories and Macronutrients

Tofu is a relatively low-calorie alternative – it is estimated that 100g of tofu contains only 62 calories overall, making it an incredibly calorie-sparse product. This means that it makes for an excellent dieting food: the number of calories is low but the volume of food (the physical mass and size of the food) is comparable to other foods that both omnivores and vegetarians may eat. This makes transitioning to tofu slightly easier for those who experience a great deal of hunger when switching diet.

The distribution of these calories among the three macronutrients – protein, carbohydrates and fats – is also positive. Tofu is mostly protein (by weight), with approximately 7g per 100, though this is more impressive by calorie: of tofu’s 62 calories, 28 are from protein. This reinforces the value of tofu as a diet food, because protein is associated with increased satiety and fat loss [2]. Fats are the second most plentiful macronutrient in tofu, at 2.7g per 100 or approximately 26 of 62 calories. This is to be expected of a product made from soy beans, and the fats are generally unsaturated and have been shown to make minimal, but positive, changes to blood cholesterol that are better than those seen in animal proteins (all other things being equal) [3]. Carbohydrates are the last macronutrient represented in tofu at only 2.4g per 100, or 10 calories. This makes tofu a suitable staple food for those who are on a very low-carb diet, or simply those who are attempting to reduce carbohydrates during resting days (those without much exercise).

Interestingly, the individual variation seen in the positive health effects of soy – primarily those linked to heart health and the reduction of cholesterols – is huge. When we look at the clinical studies, individual differences are huge and prevent an effective and definitive statement of the effects is almost impossible based on these studies alone. The best way to approach this is to simply try tofu/soy and see what effects it has on your individual blood lipid markers.

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Micronutrients: Vitamins, Minerals and Anti-nutrients

tofu

Tofu’s main downfall is that it is fundamentally nutrient-sparse. Whilst there are small concentrations of potassium (200mg) and calcium in Tofu, it is effectively a mixture of protein, fats and air. The calorie-sparsity is associated with an equally low content of important nutrients – it is for this reason that we suggest consuming tofu as part of a larger meal with nutrient-dense foods like avocado, salmon or a variety of vegetables. It is also advised to eat tofu with other foods that have a greater fiber content: consuming a diet rich in tofu and low in other foods will be damaging to the digestive system as a result of the low fiber [4]. This is no different to animal products which also have no fiber, but various other plant foods contain a large quantity of both nutrients and dietary fiber. On this basis, we might not want to include tofu as a staple but rather as an extra in salads or other high-volume, nutrient-dense foods.

“Anti-nutrients” refer to those compounds that either inhibit the body’s proper functions or absorption of necessary compounds. Soy contains two important anti-nutrients: Trypsin and Phytates. These reduce the digestion of protein and mineral uptake respectively, causing some serious concerns in the health of the body when consumed in certain quantities. Additionally, whilst soy is generally safe and there has yet to be much definitive evidence, some case studies suggest that excessive consumption of soy is associated with the suppression of testosterone in men [5].

Equol: The Determining Factor in the use of Tofu

Equol is a strain of intestinal bacteria that is essential in the digestion and absorption of soy – meaning that it is an essential aspect in the way that we process tofu and the effects that it has on our health. Equol has been found to vary drastically between individuals, including based on nationality and ethnic heritage: those with Eastern Asian heritage have an increased likelihood of possessing equol [6].

The bacterial environment of the intestine has a large impact on the health benefits and risks of consuming excessive amounts of soy-based products. The digestion of the proteins and their effect on both testosterone and the proper regulation of oestrogen is dependent on the presence of this compound in the intestines. It is estimated that 30-50% of individuals in the United States produce equol naturally – this means that soy is an appropriate dietary staple for these individuals and only these individuals: the rest of us may be able to process the food and gain the benefits of the macronutrients, but the heart health and possible hormone changes are associated with this small population.

Closing Remarks

Tofu is an innocuous food with some interesting chemical interactions. The most interesting aspect of this food is that it has some benefits and risks among those who produce equol but has neither benefits nor risks for those who do not. The best approach, as mentioned above, is to consider the macronutrient and calorie content compared to our goals, then see whether we are able to properly metabolise tofu and gain the benefits. The worst thing we can say about tofu is that you probably shouldn’t eat it in large quantities if you’re a man (though this is a positive thing among post-menopausal women who benefit from greater exogenous phytoestrogens), otherwise it is totally innocuous and neutral.

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Reference

[1] USDA nutrient database for standard reference, release 28 [URL = https://ndb.nal.usda.gov/ndb/foods/show/4889]
[2] Westerterp-Plantega et al (2009): ‘Dietary protein, weight loss and weight maintenance’. Annual review of nutrition, 29, pp.21-41
[3] Sacks et al (2006): ‘Soy protein, isoflavones and cardiovascular health’. American heart association, 113, pp.1034-1044
[4] Anderson et al (2009): ‘Health benefits of dietary fiber’. Nutrition reviews, 67(4), pp.188-205
[5] Liu et al (2011): ‘Equol-producing phenotype and in relation to serum sex hormones among healthy adults in Beijing’. Journal of hygiene science, 40(6), pp.727-731
[6] Shor et al (2012): ‘Does equol production determine soy endocrine effects’. European journal of nutrition, 51(4), pp.389-398

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