“Extensive medical questionnaires by US physicians administered to local [Okinawan] physicians who had practiced from 8 to 41 years revealed that, ‘These people had no acne vulgaris.’” – Loren Cordain et al from Acne Vulgaris: A Disease of Civilization
Okinawa is part of the Ryukyu islands of Japan. Due to the physical isolation from the rest of Japan (400 miles south of the mainland), Okinawa has a distinct culture and diet. The people of Okinawa are renowned for their longevity and in 1946 they were found to have no acne . Their unique diet may be the reason why.
- The Okinawan Diet Conundrum
- What Did They Eat?
- How Much Meat?
- General Health and Longevity
- Westernization and Declining Health
- Help the Revolution
- Meat Estimation Methodology
The diet the Okinawans ate prior to 1946 allowed them to have clear skin . However, dietary changes occurred after WWII and the US occupation that caused acne to emerge. There are only sparse references to the pre-war acne-free diet. The conundrum is: what was that diet? In this article, I will attempt to reconstruct it.
The Okinawan staple food was sweet potatoes. While several varieties were eaten, the most popular and best recognized is the purple-fleshed “Okinawan” sweet potato which has an incredibly high polyphenol and antioxidant content. They also ate a variety of vegetables including bitter melon (goya), sweet potato leaves, and various sea vegetables (more than any other region of Japan). Soy was commonly eaten as miso, tofu, and natto. Some fish was eaten, as well as small amounts pork and goat. One of their favorite spices was turmeric (commonly touted to have many health benefits). They ate rice as a secondary carbohydrate source (~12% of calories). The traditional Okinawan diet had very little dairy and few other grains (<10% of calories). [2, 3, 4]
As time went on, the Okinawan Diet underwent “Westernization” (an increase in sugar, processed foods, and meat) and “Japanization” (an increase in white rice). These changes are thought to be the cause of the drop in health of the Okinawan people. 
The earliest reports on the Okinawan Diet (1880-1919) claim that 90%+ of calories came from sweet potatoes and during holiday festivals, large amounts of meat were eaten. During this time a small amount of rice was eaten and few other grains, mostly millet, were consumed. 
Pork was the main meat consumed by the Okinawans. They ate the whole animal, blood, fat, and all. Collagen-rich portions like the skin and intestine were well desired. Cuts of pork were often trimmed of fat, not to avoid it, but rather to make it into lard, their primary cooking fat. [2, 5]
One of the features of the Okinawan Diet commonly linked to their longevity is caloric restriction. Most of the post-war reports show Okinawans eating fewer than 1800 calories per day. However, caloric consumption estimated from early reports suggest that laborers ate 3600+ calories per day. 
One of the main points of the Okinawan conundrum is how much meat they ate. Diet books advocating the “Okinawan Diet” for longevity reasons recommend a low meat diet, but this suggestion is based off of post-war data. As meat is a luxury food, it would make sense that its post-war consumption would be low due to the wrecked economy. So the question is, how much meat did they eat before the war?
In 1949 they ate on average 18 grams of fish and meat combined per day , which is one fourth of what the contemporary Japanese consumed (73 grams). In recent years, the US consumption has been close to 250 grams (which is more than 13 times what the post-war Okinawans ate). There is clearly a big difference.
What pre-war data is available? Nothing that is perfectly clear. One paper discusses old records of the diet of Okinawa from 1880 and 1919. Their conclusion was that the daily Okinawan diet of that time was at least 90%+ carbohydrate by calories . However, significantly more meat was consumed during festivals which is difficult to quantify.
Using data from Okinawan eating habits, goat herd size, census data, and other data from animal science, I attempted to reconstruct the meat consumption in 1936 (a full description of the methodology is included at the end of this article) I ended up with about 58g per day, (roughly ½ fish, ⅛ goat, and ⅜ pork). This reasonably agrees with all other data. However, depending on the assumptions made, the amount could be closer to 174g, but this is almost certainly high and should be considered the upper limit to the range of the meat they consumed. [Note: The acne-free Kitavans ate in the ballpark of 58g of meat (mostly fish) per day.]
The Okinawans ate a very high carb, low protein, low fat diet. While the estimates vary (see table), these general trends are constant. Note that the wealthy group ate more protein and fat than the lower classes, but ate significantly more during festivals.
|Group||Carbs (% Cal)||Fat (% Cal)||Protein (% Cal)||Source|
|1919 (“Wealthy”) Okinawa||91.2||1.7||7.1||[Sho 2]|
|1949 (Post-war) Okinawa||85||6||9||[Willcox 3]|
|2007 (Modern) Okinawa||58||27||15||[Willcox 3]|
Overall, the macronutrient profile is very similar to the Kitavans, but excludes fruit and coconut and replaces them with more sweet potato and some tofu/miso.
The Okinawan diet in 1949 was rich (over recommended daily allowance; RDA) in many micronutrients: Vitamins A, E, K, B1, B6, B9 (folate), C, as well as, iron, iodine, phosphorus, magnesium, potassium, and sodium. They were deficient (below RDA) in vitamins D (2%), B2 (45%), B3 (93%), B12 (27%), calcium (82%), and zinc (62%) . Their vitamin D was likely sufficient due to their sun exposure . Their low zinc is interesting considering the link between low zinc and acne and the effectiveness of zinc as an acne treatment . It could be that zinc is used up while fighting acne, and the Okinawans never faced that issue to begin with.
The Okinawan diet was notably rich in antioxidants, polyphenols, carotenoids and isoflavones due to their sweet potatoes, vegetables, seaweed, and soy. The researchers suggest that the antioxidants allowed the Okinawans to cope with oxidative stress . Interestingly, acne patients tend to be low in antioxidants and benefit from their supplementation [8, 9]. The polyphenols in combination with the large amount of fiber could have positively impacted their gut microbiome [10, 11]. The isoflavones are also called “phytoestrogens.” While their effect in humans has been debated, it is notable that birth control pills with synthetic estrogen are used to manage acne .
Aside from having no acne, the Okinawans were also a remarkably healthy people in other respects. The 1946 study of Okinawans found no malignant tumors, hypertensive disease, kidney disease, senile heart atrophy, cartilage calcification, or yaws (a skin disease). Both sexes were well proportioned and muscular. Obesity, baldness, hirsutism (excess female hair growth), diabetes, and biliary disease were all very rare. They had good teeth, good fertility, and fewer congenital defects than America . Nowadays, Okinawa is one of the “blue zones” — places with unusually high concentrations of centenarians. In addition to living longer, Okinawans to this day have lower rates of cancer, dementia, stroke, hypertension, cardiovascular disease, and osteoporosis [13, 14, 15, 16].
These benefits are partially attributed to their low glycemic diet, rich in micronutrients and antioxidants, but also to their lifestyle. They are physically active throughout their life. Elders often spend significant amounts of time gardening. The people form tight knit communities and have a sense of place and purpose. They often practiced “Hara Hachi Bu”  — eating until 80% full.
The health of the Okinawans has declined in recent years. This change is strongly associated with the Westernization of their diet and lifestyle. Fast food is becoming ubiquitous and the traditional foods are becoming increasingly uncommon. As a result, obesity, heart disease, diabetes, and depression are on the rise [19, 20, 21].
With increasing Westernization, many Okinawans are losing their health. But are they getting more acne? I would assume so, but I’m not certain. I had trouble accessing research because I don’t know Japanese… I would be very appreciative if anyone who speaks/reads Japanese would be willing to help me find the modern rates of acne in Okinawa or Japan!
- Macronutrients — very high amount of low-GI carbs (85+% of calories), low fat (~6%), and low protein (~9%). Rich in fiber.
- Fat intake limited. Sources were from the meats of fish, pork, and goat. Pig lard was the most common cooking fat.
- Rich in many micronutrients including vitamins A, B1, B6, B9, C, E, and K. Minerals: iron, phosphorus, iodine, potassium, magnesium, and sodium.
- Generally free from milk, grains (wheat, corn, etc), and high-GI carbs (sugar, flour, etc). Some rice was eaten.
- Based on wholesome foods — mainly sweet potato, vegetables, and soy (usually miso). With some fish, pork, and goat. The entire animal was eaten.
 Miyake Y, et al. Fish and fat intake and prevalence of depressive symptoms during pregnancy in Japan: baseline data from the Kyushu Okinawa Maternal and Child Health Study. J Psychiatr Res. 2013 May; 47(5):572-8
 Okinawa Census US Department of the Office of the Civil Administrator of the Ryukyu Islands: Records of Health, Education and Welfare. 1949. US Occupation Headquarters, World War II. Record Group 260.12.5 National Archives at College Park. 8601 Adelphi Road. College Park. MD 20740-6001
The estimate of 58g of meat per day draws on many types of data and I freely admit there are many possible sources of error. In 1936, there were 155,000 goats in Okinawa . Modern data says mature goats produce ~65 lb of meat and approximately ⅓ of bovine herds are slaughtered annually [23, 24]. Assuming these modern projections hold, since goat meat constituted 25% of livestock meat during that time (the remainder being pork) , roughly 13.4 million pounds of red meat were produced. Given that 574,490 people lived in Okinawa at that time , this provided each person 29g per day of red meat. Depending on paper, the ratio of fish to red to meat is ~1:1  or 5:1  post-war. I would guess that 1:1 is closer to accurate leading to 58g total per day (174g if 5:1).