Kelp supplements are obtained from long-leaved seaweeds that are also known as bladderwrack (eg Laminaria sp., Fucus vesiculosus). Kelp is a nutritious source of 13 vitamins, 20 essential amino acids as well as 60 minerals and trace elements. Kelp is a particularly rich source of calcium, magnesium, potassium, iron and iodine.
Kelp and weight loss
Kelp is used to support weight loss because it is a rich source of iodine, which is needed for the production of thyroid hormones. Thyroid hormones (thyroxine, tri-iodothyronine) regulate the metabolic rate and if iodine is lacking in your diet, this can lead to reduced thyroid function and weight gain. The alginates present in kelp also help you feel full and reduce appetite so you eat less overall.
Kelp provides iodine
Lack of iodine is a growing problem now that we are all advised to cut back on salt intake – previously, iodised salt was an important dietary sources of this weight loss mineral. Other sources of iodine include dairy products and seafood. Seaweed typically supplies as much as 712 mcg iodine per gram, and is one of the richest dietary sources available.
Kelp blocks fat absorption
As well as providing iodine to help ensure that your metabolic rate is optimal for fat burning, scientists at Newcastle University have found that alginate fibre, which is naturally present in kelp, is also effective at reducing the absorption of dietary fat, in a similar way to the weight loss aid, Alli. In a typical diet, around 40% of calories come from fat, and this must be digested by enzymes known as lipases, before the fat can be absorbed. By blocking the effects of lipases, kelp alginates reduce fat absorption so you lose more calories in your bowel motions. Research suggest that kelp alginates can reduce the amount of dietary fat available for absorption by around 75%.
Kelp makes you feel fuller
Studies also show that kelp alginate swells in the intestines to increase feelings of satiety so you eat less overall. This is a similar effect to that seen with konjac glucomannan. Alginates are already used in foods to stabilise jam and to maintain the frothy head on a pint of beer. Alginates are now being added to some weight loss foods.
How effective is kelp for weight loss?
One study investigated the effects of adding kelp alginate supplements to an energy restricted diet in which participants ate around 300 kcalories per day less than their estimated needs. A total of 99 obese people took part. All followed the weight loss diet, with half also taking kelp supplements, and half taking placebo capsules. The supplements were taken with a drink, three times a day, before meals, for 12 weeks.
Overall, 80 people finished the trial, and those who took the kelp alginate supplements lost an additional 1.74 kilograms more weight than those taking placebo (6.78 kg compared with 5.04 kg).
Kelp and fucoxanthin
Edible brown seaweeds and marine algae contain a unique carotenoid pigment known as fucoxanthin. Fucoxanthin is classed as fat burner as it increases fat metabolism to aid weight loss. Fucoxanthin works as an antiobesity agent in a number of ways, including:
- suppressing fat production in the liver
- switching on genes needed to burn fat in white fat cells
- causing white fat cells to act more like brown fat cells (which burn fat to generate heat)
- suppressing the production of new fat cells
- decreasing blood levels of leptin, the hunger hormone.
In one study, 151 obese women plus 41 women with fatty liver disease, took a combination of 300 mg pomegranate seed oil and 300 mg brown seaweed extract (providing 2.4 mg fucoxanthin) lost between 4.9kg and 5.5kg body weight and visceral fat (3.5 cm reduction in waist size) within 16 weeks. Liver function tests also improved.
Dose of kelp for weight loss
A typical dose of kelp extracts is 200mg – 600mg daily, providing around 225 mcg of natural source iodine to support thyroid function.
Skin patches containing iodine derived from kelp extracts are also available to support weight loss.
Do not take kelp supplements if you have thyroid problems, except under the advice of your doctor.