Ask the Tokyo Dietitian: Japanese plant-based protein sources beyond tofu and your nutrition questions answered

Welcome to another installment of "Ask the Tokyo Dietitian,” where you can get expert insights on food and nutrition, tailored specifically for life in Japan.

Whether you're looking for tips on how to balance traditional Japanese foods with modern dietary needs, navigating local food labels or want to learn more about the latest in nutrition science, our registered dietitian is here to help. Each month, we'll tackle common questions, dispel myths and provide practical advice to support your health and wellness journey.

Have a question? Ask away by emailing us at tokyodietitian@japantoday.com and your question may be featured in an upcoming article.

Both "soramame" (broad beans) and "natto" (fermented soybeans) are nutritious plant-based protein sources that are readily available throughout Japan. Image: shine hattori, freeangle/Pixta

Question: I’m a vegetarian living in Tokyo and I am trying to increase my protein intake. Aside from tofu, what are your favorite plant-based protein sources that are widely available here in Japan?

Tokyo Dietitian: While the quality and variety of tofu in Japan is incredible, I think it’s great that you want to diversify your protein sources. I often get this question from those new to Japan, as Japan doesn’t offer as many vegetarian-friendly convenience products, like ready-made meals or entrees, compared to other countries. Yet if you look beyond pre-made veggie burgers or meat alternatives, Japan has a robust selection of whole foods that are high in protein. Whether you’re a vegetarian or not, I recommend eating more whole food protein sources to cut back on excess additives, sugar or salt.

Below are a few of my favorite plant-based protein sources that are appropriate for those on a vegetarian diet. Note that this is not an exhaustive list, and I hope that vegetarians and meat eaters alike try and enjoy these nutritious sources of protein.

High-protein soy foods (excluding tofu):

• Edamame (soybean). I use both fresh and frozen varieties and like to throw them in a salad or stir-fry for a protein boost. 100 grams of edamame contains around 12 grams of protein.
• Natto (fermented soybeans). While some may say that this is an acquired taste, those who enjoy it will consume approximately 10 grams of protein per 100 grams of natto.

High-protein beans and legumes:

• Soramame (broad or fava beans). These beans make a delicious side dish or snack and are typically consumed after boiling or grilling. Need some food on the go? Look for the packaged snack Miino at the convenience store, which is made of lightly fried broad beans. Broad beans contain about 8 grams of protein per 100 grams of cooked beans.
• Peas. Spring is a perfect time to add more peas into your diet, either on their own or in the form of mame gohan (green pea rice). 100 grams of cooked peas contain approximately 5 grams of protein.

Other high-protein foods:

• Fu (seitan). Made from wheat gluten, this was traditionally used in soups or hot pot dishes in Japan and other parts of Asia. Exact protein estimates will vary depending on formulation and preparation, but some nutrient databases list seitan as containing up to 75 grams of protein per 100 grams!
• Soba (buckwheat) noodles. 100 grams of cooked soba noodles contain around 5 grams of protein and are also a good source of fiber as discussed in a previous Ask the Tokyo Dietitian article.

Japan is known for its wide array of collagen supplements that include drink, pill and powder forms. Image: Civil/Pixta

Q: I’ve noticed that there are many different types of collagen supplements that seem to be popular here in Japan. What do people take collagen for, and should I be taking a collagen supplement, too?

TD: Like you, I was also surprised to see the wide variety of collagen supplements lining the store shelves in Japan after moving here. Either as a standalone supplement or added to other supplements and products, collagen supplements are typically in drink, pill or powder form.

Why take collagen? Those investing in these supplements are typically after one purported benefit: anti-aging. This is because collagen is the most abundant protein in the body, and is found in large quantities in your skin, ligaments, tendons, bone, hair, nails and other tissues. As we age, our bodies begin to produce less collagen. This can result in wrinkles, sagging skin, joint pain and thinner hair and nails. Therefore, some people believe that ingesting collagen will help boost your body’s supply and combat the signs and symptoms of aging associated with collagen loss.

While the research on the effectiveness of collagen supplementation is less than certain, some results show promise. A 2021 meta-analysis from the International Journal of Dermatology found that those taking collagen experienced improvement in the firmness and moisture content of their skin as well as the decreased appearance of some wrinkles. Yet it is unclear if this was due to the collagen or the other components in some of the supplements. A few trials and reviews have also shown minor benefits related to joint pain and skin improvement, but more research needs to be done to confirm these benefits.

If you’re interested in taking a collagen supplement, I’d recommend discussing it with your doctor first to ensure it’s appropriate for your medical condition. I’d also recommend considering the dosage needed to achieve the effect you’re looking for. Some of the popular supplements I reviewed at a local drugstore contained small amounts of collagen — less than 2 grams per dose. Most research studies supporting collagen use involve dosages of 2.5-10 grams or more per day, so be sure to review your dose to get the best results possible.

Victoria Lindsay, MS RD, is a registered dietitian and nutrition consultant working at Tokyo Medical & Surgical Clinic and her Tokyo-based private practice. To get in touch, please visit: www.victorialindsayrd.com.