Kaempferol Simply Explained

1. What It Is About

Kaempferol belongs to the flavonoids. These are colour and protective substances that occur in many plants. Flavonoids count among the polyphenols, a large group of plant substances. In the plant, kaempferol protects against stress from light and oxygen. Larger amounts are found in green leafy vegetables such as spinach and kale, as well as in tea, broccoli, apples, onions and in medicinal plants such as Ginkgo biloba. In the plant, kaempferol is often bound to sugar. The body must first break this connection so that the substance can be absorbed. How much of it actually reaches the blood varies greatly from person to person. It depends on with which food kaempferol is absorbed and which bacteria live in the gut. Part of it is converted in the gut and transported further in another form. Therefore, quantity specifications are difficult to compare and measurement values difficult to interpret.

2. What Studies Show

The best investigated is a study with 33 working women and men 1. They received kaempferol or a placebo, that is a preparation without active substance, for two weeks, after which the assignment was swapped. Neither the participants nor the carers knew who received what. In the kaempferol weeks the participants took more steps, covered longer distances and undertook more outings, especially at weekends. Sleep quality was also better and the pulse lower. A measurement value for the intervals between heartbeats rose. These findings are indications, but not yet confirmed: the study lasted only two weeks and only a few persons took part.

Regarding thinking, memory and attention there are two long observational studies. In the first, 960 people between 58 and 99 years of age were followed 3. Those who ate more green leafy vegetables declined mentally more slowly over approximately 4.7 years. Kaempferol was one of the substances examined individually in this context. In the second study, 961 people between 60 and 100 years of age were followed over approximately 6.9 years 4. Here too a higher intake of flavonols, to which kaempferol belongs, was associated with slower mental decline. This work gives no separate figures for kaempferol alone.

During cancer therapy blood formation in the bone marrow can decline. A review article has collected studies on this 2. In animal and cell experiments the white blood cells increased and the cells in the bone marrow proliferated more strongly. Whether the same occurs in humans is so far only a hypothesis.

Kaempferol is furthermore described as anti-inflammatory and antioxidant. Antioxidant means: a substance intercepts aggressive oxygen compounds. These properties have so far been observed mainly in cell and animal experiments.

3. What Remains Unclear

Of 166 evaluated papers only two were controlled human studies. Most investigations were carried out on cells in the laboratory or on animals. Whether these observations can be transferred to humans is an open question. The few controlled human studies involved small groups and lasted only briefly, so effects over longer periods are not clarified. Kaempferol is moreover rarely studied alone. It is usually contained in a plant extract or in a food together with many other substances. In such cases it cannot be said which substance explains which observation. Absorption into the body is also difficult to measure because kaempferol is rapidly converted and the values fluctuate strongly. What would clarify these questions are larger controlled studies with uniform preparation, longer time periods and measurements in the blood.

4. What This Means in Everyday Life

Kaempferol occurs in entirely ordinary foods, and the human observations come predominantly from persons who ate a lot of vegetables. What became visible in the studies was mainly more movement and better sleep in a small group over two weeks as well as slower mental decline in long observational studies. Such work shows associations, but not causes. Kaempferol is moreover only one of many substances in these foods. Whether it itself produces an effect cannot be deduced from this. The next step would be to examine a controlled study that follows kaempferol alone in identical form over a longer period and measures how much actually reaches the blood.

All details with study numbers and sources: Detailed Page on Kaempferol. For Children: Kaempferol for Children.