Nanotechnology’s Impact on Functional Foods, Supplements (How Nanotechnology Will Impact Functional Foods, Dietary Supplements)

Improved Delivery Systems

Delivery system improvement holds the greatest potential. Previously, only a few choices existed for combining incompatible oil/water media; these were mainly detergent-like solubilizing agents, which have their own undesirable characteristics, or the use of oil-in-water or water-in-oil emulsions that can be unstable, especially at high concentrations. However, NSPs of traditionally incompatible substances can disperse in one another with greater ease, such as oil-based vitamin E or lycopene in aqueous environments, yielding a much more stable and homogeneous product. Hostile environments have plagued formulators for ages, with fragile (labile) substances (delicate chemical flavor esters or enzymes in food) that degrade before reaching a point where they become useful. Nano-encapsulation of these labile substances in liposomes (essentially, lipid envelopes) can survive the depredations of extreme pH, enzymes, moisture (or lack of it), as it provides protection.

Other possibilities include nanoencapsulated substances that are released upon application of heat (such as in cooking or microwaving, the latter of which does not allow the browning reaction to take place) or released upon mechanical agitation (such as chewing gum with prolonged flavor release beyond the conventional 10 to 20 minutes). Nano-encapsulation can also be utilized to increase the bioavailability of a substance, such as vitamins or minerals, as well as to mask undesirable odors such as those encountered with omega-3 fatty acids derived from fish oil.

Uptake, Kinetics, Distribution

One of the most intriguing aspects of nanotechnology to life scientists is the ability of NSPs to be efficiently absorbed. For example, the majority of vitamin E is not absorbed, but tends to pass through the intestine for excretion. As NSPs, slowly absorbed or poorly absorbed substances can now achieve total absorption, allowing for the use of much lower amounts in the product and, therefore, saving on raw material costs.

Additionally, NSPs may not follow conventional pathways of excretion. Instead, they may be reabsorbed and recycled through the body until they are finally complexed with a protein or other macromolecule. Under this scenario, the NSPs would tend to stay in the body much longer, which may be viewed as a beneficial quality. However, this ease of absorption and resistance to excretion may also be the source of difficulties and represent a significant downside. NSPs may actually travel through or even between cells lining the intestine, circumventing conventional barriers that normally prevent such rapid absorption. Access to the circulatory system may be remarkably fast and may result in effects only seen with an equally rapid delivery such as intravenous injection. The safety of many conventional substances is predicated on slow absorption and a predictable rate of excretion. Changing these parameters may require a re-assessment of the safety of the substance as an NSP.

The ease of bypassing conventional barriers may not end with the intestinal wall, but may allow entry into sites not normally accessed by exogenous substances, such as the brain, thyroid and other sites, and cause adverse reactions. Likewise, NSPs able to cross the placental barrier may induce birth defects when the bulk matter was known not to have an effect, simply because it did not gain access to the fetus.

The lack of excretion may also pose a problem because macrophages, whose function is to absorb particles resistant to excretion, will tend to sequester in storage organs, such as the liver and spleen, and these organs may then swell and become non-functional. Testing to discover these possible effects is essential and prior approval or use of a substance as a bulk molecule does not mean the substance is safe as an NSP.

Continue...

Pages: Previous 1 2 3 Next