Vinegar has a long history as it's been used worldwide for decades. It was originally brought into Japan from China in the 4th - 5th century.
Rice vinegar is used mainly for cooking Japanese meals and it has a milder and sweeter flavor compared to western-made vinegar.
In Yakuzen, vinegar is categorized as a warm food that warms your organs and improves Qi and blood circulation. This action helps you relieve blood stasis such as stiff back and other symptoms due to QI stagnation.
Vinegar studies suggest consuming about 1-2 tablespoons daily, otherwise, it could irritate the stomach lining.

Nature – Warm（温）
Channels – Liver (肝), Stomach (胃)
Flavor – Sour (酸), Bitter (苦)

How does vinegar help you?

1. Improve your Qi and blood circulation
2. Remove blood stasis
3. Improve digestion
4. Eliminate toxins and kill internal parasites

Good for the following symptoms

1. Bleeding caused by blood stasis
2. Pains caused by blood stasis
3. Stiff back
4. Sensitivity to cold
5. Period cramps caused by blood stasis/cold
6. Indigestion
7. Poor appetite
8. Heavy stomach
9. Food poisoning
10. Itchy skin

Cautions

It's very important to know about your body conditions before choosing foods.
Do not eat too much of particular foods at once.
Do not eat the foods you are allergic to.
There are foods to avoid if you are pregnant / have a disease. Ask your doctor before you start Yakuzen.