The prevalence of obesity has increased dramatically worldwide, making weight reduction through lifestyle management an urgent matter. While numerous supplements are marketed for their anti-overweight properties, many lack proper scientific evidence. However, traditional Japanese herbs and dietary practices offer promising avenues for supporting weight loss and overall health. This article explores several Japanese herbs and foods, examining their potential benefits and the scientific research behind them.
Konjac: The "Broom of the Stomach"
Konjac, or konnyaku, is a traditional Japanese health food derived from the konjac root vegetable. Known for its distinct rubbery and jello-like texture, konjac is virtually flavorless before seasoning. Often called the "broom of the stomach," it's praised for its ability to cleanse the bowels of toxins and waste.
Benefits of Konjac
- High in Dietary Fiber: Konjac is rich in glucomannan, a dietary fiber that forms a gel when digested, coating the gut lining and promoting healthy bowel movements.
- Blood Sugar Regulation: Konjac helps slow spikes in blood sugar levels and alkalizes the body, making it beneficial for diabetics and those seeking a healthy lifestyle.
- Cholesterol Reduction: Research suggests that konjac's glucomannan content may lower total cholesterol levels by reducing the absorption of triglycerides and LDL cholesterol.
- Weight Loss Aid: Konjac is low in calories and fat, rich in minerals, and has high satiety due to its ability to absorb up to fifty times its weight in water, creating a feeling of fullness. This makes it a valuable addition to weight loss diets like keto, paleo, and slow carb.
Konjac in Japanese Cuisine
In Japan, konjac is available in various forms:
- Shirataki Noodles: Thin, translucent noodles commonly used in dishes like sukiyaki and nikujaga. Their plain taste balances the rich broths of these dishes.
- Traditional Konjac: Cut into purple or white triangular and rectangular slices.
Konjac Beyond Food
Konjac's water-retention properties also make it an excellent facial cleansing sponge. These sponges gently exfoliate, remove impurities, and are mild enough for babies' skin. They are often combined with ingredients like charcoal or camellia oil and are biodegradable.
Ashitaba: A Nutritious Green and Yellow Vegetable
Ashitaba is a green and yellow vegetable of the Apiaceae Angelica family, rich in vitamins and minerals. It contains high levels of protein, carotene, potassium, vitamins E, K, and B, pantothenic acid, niacin, and dietary fiber.
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Phytochemicals and Their Effects
Ashitaba contains 4-hydroxyderricin (4HD) and xanthoangelol (XAG), phytochemicals with anti-tumor, anti-inflammatory, and anti-diabetic activities. These compounds inhibit the differentiation of fat cells by suppressing certain proteins, potentially preventing obesity and related disorders.
Clinical Evidence
A study reported that consuming ashitaba green juice (6.2 g/day) for eight weeks resulted in significant reductions in visceral fat area, body weight, BMI, and body fat in adults with metabolic syndrome.
Bofu-tsusho-san (BF): A Traditional Herbal Medicine
Bofu-tsusho-san (BF) is a traditional Japanese herbal medicine ("kampo") comprising 18 crude components. It has been used to treat obesity, constipation, and hypertension.
How BF Works
BF activates brown adipose tissue (BAT) and promotes lipolysis in white adipose tissue (WAT). It may also inhibit cyclic adenosine monophosphate (cAMP) phosphodiesterase, similar to caffeine.
Clinical Trials
A randomized, double-blind, placebo-controlled study of BF in obese Japanese women with impaired glucose tolerance (IGT) and insulin resistance (IR) showed significant reductions in body weight and abdominal visceral fat after 24 weeks.
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Meta-Analysis of Bofu-tsusho-san (BTS)
A meta-analysis of randomized controlled trials evaluating the effects of BTS on BMI, waist circumference, glycolipid metabolism, and blood pressure in participants with obesity found that BTS significantly reduced BMI compared to controls.
- Study Selection: The analysis included seven studies with 679 participants.
- Results: BTS significantly reduced BMI (mean difference: -0.52 kg/m2) but did not show significant differences in waist circumference, glycolipid parameters, or blood pressure.
- Sensitivity Analyses: These analyses showed robust outcomes for the primary endpoint.
Components of BTS
BTS comprises 18 crude drugs, including Scutellariae Radix, Glycyrrhizae Radix, Platycodi Radix, and others. It is believed to improve various problems, such as constipation, in obese patients.
Mechanisms of Action
Previous studies suggest that BTS reduces visceral fat, improves glucose tolerance, and has potential appetite-suppressant activity through regulating the ghrelin system.
BFT and Gut Microbiota
BFT has been shown to modify the gut microbiota, particularly increasing Akkermansia muciniphila (AKK), which enhances the intestinal barrier function. This can lead to improved insulin sensitivity and glucose tolerance.
- Impact on Gut Microbiota: BFT reduced Bacteroidetes and increased Verrucomicrobia, mainly AKK.
- Gut Barrier Function: BFT strengthens the gut barrier, decreasing gut permeability and alleviating endotoxemia.
- Adipose Tissue Inflammation: BFT relieves inflammation in adipose tissue and steatohepatitis.
Other Japanese Dietary Supplements
Research has also explored other dietary supplements in the Japanese market for their anti-obesity effects. These supplements aim to affect various pathways, including lipid absorption, energy intake and expenditure, increased lipolysis, and decreased lipogenesis and differentiation.
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Capsinoids
Capsinoids, found in non-pungent chili peppers, may increase basal metabolism, fatty acid oxidation, and decrease body fat. Studies have shown that capsinoids can increase cold-induced thermogenesis.
EPA and DHA
EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are essential omega-3 fatty acids found in cold-water fish. They may play a role in obesity by influencing the ratio of EPA to arachidonic acid (EPA/AA ratio).
- Mechanisms: EPA is a ligand of PPARα and activates genes encoding key enzymes of fatty acid transport and β-oxidation. It also improves glucagon-like peptide-1 (GLP-1) levels, enhancing insulin secretion and satiety.
- Clinical Trials: Fish oil supplementation has been shown to lower triacylglycerols, increase HDL cholesterol, and improve endothelium-dependent arterial vasodilation.
Coleus Forskohlii (CF)
Coleus forskohlii (CF) is a native Indian coleus plant used in Ayurvedic medicine. Its active ingredients, forskolin and diterpene, act directly on adenylate cyclase, which activates cAMP and stimulates fat catabolism.
Hydroxycitric Acid
Hydroxycitric acid, found in the rinds of Garcinia cambogia (GC), decreases the synthesis and secretion of very low-density lipoprotein (VLDL) in the liver. It may also inhibit de novo lipogenesis.
Lactoferrin (LF)
Lactoferrin (LF) is an iron-binding glycoprotein found in exocrine secretions. It influences master regulators of adipocyte differentiation and inhibits lipid accumulation in preadipocytes. Studies have shown that LF can reduce visceral fat area, body weight, BMI, and hip circumference.
L-Carnitine (LC)
L-Carnitine (LC) is a vitamin-like amino acid derivative involved in lipid metabolism. It promotes the transport of long-chain fatty acids into the mitochondria for β-oxidation.
Additional Herbs and Spices for Weight Loss
Beyond traditional Japanese remedies, other herbs and spices have shown potential in supporting weight loss:
- Fenugreek: May help control appetite and reduce food intake.
- Cayenne Pepper: Contains capsaicin, which can boost metabolism and reduce hunger.
- Ginger: Can reduce body weight, body mass index, and body fat percentage.
- Oregano: Contains carvacrol, which may impact genes and proteins controlling fat synthesis.
- Ginseng: May aid weight loss and alter gut microbiota composition.
- Caralluma Fimbriata: Thought to increase serotonin levels, affecting appetite.
- Turmeric: Contains curcumin, which may have positive effects on BMI.
- Black Pepper: Contains piperine, which may influence weight loss.
- Gymnema Sylvestre: Can reduce the perceived sweetness of foods, warding off sugar cravings.
- Cinnamon: Stabilizes blood sugar, reducing appetite and hunger.
- Green Coffee Bean Extract: High in chlorogenic acid, which may have weight-lowering effects.
- Cumin: May accelerate weight loss and fat burning.
- Cardamom: May support weight loss, though research is limited.