Kelp Seaweed

Kelp is an excellent source of iodine, potassium, magnesium, iron, and calcium [2].

Depending on the type of kelp or seaweed, the nutrient profile can vary greatly [3].

Laminarin is a specific type of kelp in the brown algae family rich in nutrients (iodine, potassium, magnesium, calcium, and iron). Its compounds may also block tumor growth and spreading [2].

Another type of seaweed – Gracilaria changii – is rich in fiber content and essential amino acids (the building blocks of proteins) [4, 3].

Kelp also contains a complex long-chain carbohydrate (polysaccharide) called fucoidan. Fucoidan is responsible for several potential effects of kelp, including antioxidant, anti-inflammatory, and cancer fighting [5, 6, 7].

Kelp is also an excellent source of vanadium, used in clinical studies to lower glucose levels in individuals suffering from diabetes type 1 and 2. Fucoxanthin, a pigment found in brown seaweed, may also boost weight loss [8, 9, 10, 11, 12].

Mechanism of Action
The high iodine content in kelp supports the production of thyroid hormones T3 and T4. If iodine deficiency is severe and prolonged, the thyroid gland enlarges and forms a goiter. This can also lead to a lack of thyroid hormones (hypothyroidism) [13, 2].

Kelp has potential cancer-fighting properties. Fucoidan from kelp may kill cancer cells and stop their growth [5].

Nutrients from seaweed carry potential health benefits. Dietary fiber, peptides, lipids, and minerals protect the heart. They may help reduce markers of heart disease, protect the cells (reducing oxidative stress), reduce inflammation in blood vessels, reduces high blood pressure, and decrease blood clotting [14].
Effective for:
Inducing Labor and Facilitating Abortion Procedures
Sticks made of Laminaria (a type of kelp) are used to induce birth and perform abortions. Different methods and amounts are used depending on the trimester (inserted into the cervix). The sticks cause the release of prostaglandins, which act as hormones that help initiate womb contractions [15, 16].

Laminaria sticks can mechanically assist in terminating pregnancy from the first to the late second trimester of pregnancy. In one study (longitudinal), 171 late second-trimester abortions were performed using Laminaria (cervical preparation). Only one had serious complications (no contractions during delivery) and 9 required additional safety measures [17, 15, 18].

However, there are better and safer methods for inducing labor or abortion. Depending on the circumstances, doctors may [19]:

Ripen the cervix with synthetic prostaglandins
Rupture the amniotic sac
Give intravenous Pitocin (synthetic oxytocin)
Possibly Effective for:
1) Iodine Deficiency
Kelp has a high iodine content (200 to 400 µg). It improved thyroid function in a study of 7 patients with severe motor and intellectual disabilities and hypothyroidism due to iodine deficiency. Patients were given 1 to 2 grams of powdered kelp daily, and this treatment restored thyroid function, increasing the concentration of iodine in the urine [20].

In another trial on 36 healthy people, kelp increased the levels of the hormone that stimulates the thyroid gland (TSH) [21].

However, excessive amounts may have the opposite effect. In a Japanese clinical trial on 13 people, eating 15-30 grams of kelp per day suppressed thyroid function, resulting in low thyroid hormone levels [22].

All in all, the evidence suggests that appropriate kelp doses may improve iodine deficiency and thyroid function. Be sure to discuss with your doctor if it may be helpful in your case and how you should take it.

2) Diabetes
Powdered seaweed pills reduced sugar levels in a study of 20 subjects with type 2 diabetes (RCT), taken daily for 4 weeks. It decreased fasting and post-meal blood sugar levels and serum lipid (fatty acid) levels. Also, the pills increased HDL levels, which help prevent heart disease associated with diabetes [23, 24].

In another trial on 65 people, polyphenols extracted from two different kelp species lowered blood sugar, insulin resistance, and inflammatory markers [25].

However, an extract with seaweed polyphenols was ineffective at lowering blood sugar levels (both before and after meals) in a trial on 26 people [26].

Kelp is a great source of vanadium. Oral vanadium supplements (150 to 300 mg daily) given to 14 type 1 diabetic patients (longitudinal study) for 30 months decreased fasting blood sugar levels by over 30%. Vanadium also decreased cholesterol levels. It caused no major side effects, with the exception of mild diarrhea at the beginning of the treatment period [27, 10].

Vanadium mimicked insulin in animal studies. In one study with diabetic mice, a vanadium-based compound reduced blood sugar levels and diabetic symptoms (such as thirst, hunger, and weight loss), with no side effects [28].

Although limited, the evidence suggests that kelp and its compounds may help lower blood sugar and insulin resistance.

3) Weight Loss
A study of Xanthigen, which is a type of kelp, showed reduced body weight, waist circumference, and body and liver fat content in 151 non-diabetic obese women. It also improved liver function tests and increased energy use at rest [29].

Mice fed fats from seaweed had increased markers of weight loss in fat tissue. Fucoxanthin, a pigment from seaweed, produced these effects [12, 30].

In a cell study, alginate (a carbohydrate present in the walls of algae and seaweed) reduced the activity of a protein in the pancreas that breaks down fats (pancreatic lipase). Lower activity reduces fat breakdown, leading to fewer fats being absorbed after a meal [31].

Again, the results are promising but limited. Further clinical research is needed before concluding for certain that kelp helps with weight loss.

Insufficient Evidence for:
The following purported benefits are only supported by limited, low-quality clinical studies and some animal research. There is insufficient evidence to support the use of kelp for any of the below-listed uses until the existing results are replicated in larger, more robust clinical trials. Speak with a doctor before taking kelp supplements and never use them as a replacement for approved medical therapies.

1) Blood Clotting and Flow
In a clinical trial on 24 people, dietary fucoidan prevented the formation of blood clots by increasing the production of two messengers (hydrogen peroxide and prostacyclins) in the blood vessels [32].

Fucoidan infusion decreased clotting in bleeding in rats. The rats also had less inflammation around the area of swelling, moved easier, and had better memory retention after fucoidan treatment [33].

Fucoidan supplements prevented blood clotting in mice. The supplements also decreased the activity of blood clot stimulators (platelets and fibrin). In another study, fucoidan injections in mice led to enhanced cell survival and function in tissues with low blood supply (ischemia) [34, 35, 36, 37].

In tissues with low blood supply, fucoidan decreased cell death proteins (including MAPK, JNK, and caspase-3) and harmful compounds (reactive oxygen species) [35].

2) Cancer
Below, we will discuss some preliminary research on kelp’s potential anticancer. It’s mostly in the animal and cell stage and clinical trials have yet to determine if it may be useful in anticancer therapy.

Do not under any circumstances attempt to replace conventional cancer therapies with kelp, its active compounds, or any other supplements. If you want to use it as a supportive measure, talk to your doctor to avoid any unexpected interactions.

A study of 15 postmenopausal women, 10 of whom were breast cancer survivors, looked at the effects of brown seaweed supplementation over a 3-month period (alternating with placebo). Seaweed decreased an important marker of breast cancer recurrence by half (receptor uPAR) after 4 weeks [38, 39].

Fucoidan, a key component of seaweed, may fight cancer and stop tumor growth, based on both cell and animal models. In addition, seaweed supplements and algae extracts, including the brown seaweed Laminaria, reduced colon, breast, and prostate cancer activity [40, 41, 42, 43].

Fucoidan injections or fucoidan, when given in food, slowed tumor growth in mice. Fucoidan killed cancer cells by activating the immune system (via natural killer cells) [40, 44].

Fucoidan reduced the growth of leukemia cells and killed 2 out of 4 lines tested in a study. In another study in cells and mice, fucoidan stopped the growth and spread of lung cancer cells by blocking growth pathways (Akt–mTOR and NF-kB) [45, 44].

3) Hepatitis C
In a study of 15 patients with chronic hepatitis C, fucoidan from brown seaweed was used to treat virus-related liver diseases. After 8 to 10 months of treatment, hepatitis C virus (HCV) levels in the blood significantly decreased [46].

Additionally, this study also examined alanine aminotransferase levels, a protein whose presence correlates to a more severe HCV infection. The blood tests also present a decrease in alanine aminotransferase levels. Despite the positive laboratory findings, these results did not lead to significant clinical improvements [46, 47].

Animal and Cell Research (Lack of Evidence)
No clinical evidence supports the use of kelp for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies listed should not be interpreted as supportive of any health benefit.

In a rat model, fucoidan (present in kelp) was used to reduce inflammation caused by immune cells in the brain. Fucoidan improved animal behavior, reduced harmful compounds (TNF-alpha), prevented neuron loss, and protected the cells from damage (reducing reactive oxygen species) that can cause neurodegeneration [48, 49, 50]

In a brain and spinal cord cell study, fucoidan reduced inflammation (blocking nitric oxide (NO) and prostaglandin E2 production). Fucoidan also blocked inflammatory proteins (cytokines IL-1β and TNF-alpha) and the inflammation pathway (reducing NF-kβ and p38 MAPK) [6, 51, 49, 52, 53, 54, 55].

Fucoidan reduced all important actors in the inflammatory cascade in cell studies. In brain immune cells (microglia) fucoidan from brown seaweed showed promise for treating neurodegenerative diseases caused by inflammation [6, 56, 57].

Fucoidan blocked the growth of the herpes simplex virus type 1 (HSV-1) in infected mice. Mice given fucoidan had better survival rates. The treatment improved immune response (innate and adaptive), increasing antibody production [58].

Brain Protection
In a study (cell), seaweed extracts (including kelp) protected brain cells from death in cell models of Parkinson’s disease and improved cell survival. It also protected from toxins, helping the cells avoid death (via hydrogen peroxide and caspase-3) [59, 60, 61, 62].

Bone Growth and Strength
In a rabbit model, fucoidan helped create new vessels, essential for communication with bones and bone repair. It also partially improved bone growth in rabbits with defects in skull formation [63].

In human stem cells, fucoidan boosted the development of cells that build bones, called osteoblasts. Fucoidan also increased the growth of new vessels, improving communication with bones [63, 64].

In another cell study, fucoidan increased proteins that promote bone and mineral formation (via BMP-2, osteocalcin, and ALP). Fucoidan given to aged female mice increased bone density and weight suggesting that fucoidan may play a role in treating age-related bone loss [65, 66, 67, 68].

Blood Pressure
Ten protein extracts from a particular sea kelp (wakame) were given to rats with high blood pressure. Of the 10 extracts, 4 experienced decreased blood pressure after both a single dose and routine use [69].

In a cell study, 5 organic brown seaweed (kelp) extracts blocked an important enzyme that may contribute to high blood pressure (Angiotensin-converting Enzyme, ACE). This enzyme is often a target for blood pressure-lowering drugs [70, 71].

Blood Fat Levels
A 1% or 5% fucoidan (from kelp) diet reduced fat in mice that were fed a high-fat diet over 12 weeks. Kelp reduced the weight of liver and fat tissue, glucose, and fats (cholesterol and fatty acids) in the blood. It increased the activity of a protein that breaks down fatty acids (lipoprotein lipase), dissolving the plaque in arteries [72].

The antioxidant properties of fucoidan (from kelp) were confirmed in a cell study that tested its 2 major components, sulfate and fucose. Fucoidan showed antioxidant effects and has the potential to be used as a natural antioxidant [7].